UFO High Bay Wattage Chart by Area & Height

UFO High Bay Wattage Chart by Area & Height

If you want a fast, reliable way to size UFO high bay lights, start with lumens and area—not watts or marketing “HID equivalents.” This guide gives you ready‑to‑use wattage charts by square footage and mounting height, plus simple rules of thumb you can apply on any project.

According to the industrial guidance from the Illuminating Engineering Society (IES), typical warehouses need roughly 20–30 foot‑candles (fc) for bulk storage and 30–50 fc for active areas like picking or packing. Since 1 fc ≈ 10.76 lux, that translates to about 215–538 lux. The charts below translate those targets into recommended lumens and UFO high bay wattage by area and height.

How to use this page

1. Find your ceiling height and room size.
2. Choose your application type (storage, work, detail).
3. Use the suggested lumens and wattage per fixture as a starting point, then fine‑tune with a layout or IES files.

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1. Key design assumptions behind the wattage chart

Before you dive into numbers, it helps to understand the assumptions baked into every wattage chart. This lets you adjust intelligently for your own project instead of blindly copying values.

1.1 Foot‑candles, lumens, and area

A wattage chart is just a shortcut to this basic relationship:

Total lumens needed ≈ Target fc × Floor area (ft²)

Example: a 10,000 ft² warehouse targeting 30 fc needs about 300,000 lumens initially. This matches guidance summarized by the IES industrial lighting recommendations, which put medium‑activity warehouses around 30 fc.

Once you know total lumens, you decide:

• How many fixtures you want.
• How many lumens each fixture should deliver (catalog lumens).
• Where they should go to keep uniformity reasonable—typically max:avg ≤ 2:1 for comfortable spaces.

1.2 Efficacy: why watts alone are misleading

A common misconception is that “a 150 W UFO high bay is roughly equal to a 400 W HID,” so any 150 W fixture will do. In practice, efficacy (lumens per watt, lm/W) varies dramatically.

Field comparisons and spec sheets collected in DOE’s FEMP LED luminaire guidance show high‑bay products spanning from under 120 lm/W to over 170 lm/W. That means:

• A 150 W at 120 lm/W fixture ≈ 18,000 lumens.
• A 150 W at 160 lm/W fixture ≈ 24,000 lumens.

So a modern 150 W high‑efficacy UFO can outperform an older 200 W design in both light output and energy savings. This aligns with the research insight that a single lumen‑per‑watt figure does not define all UFO high bays; a 150 W high‑efficacy unit can outperform a 200 W legacy unit (IG4).

Takeaway: always read the LM‑79‑based lumen rating, not just wattage. LM‑79 is the Illuminating Engineering Society (IES) approved method for measuring LED luminaire output, efficacy, color, and power factor, as explained in the ANSI/IES LM‑79‑19 overview.

1.3 Maintenance factor: design for long‑term light levels

Another expert mistake is sizing a design to the initial lumens and forgetting depreciation. Real installations lose light over time due to:

• LED lumen depreciation (LM‑80/TM‑21 behaviour).
• Dirt on optics and reflectors.
• Thermal stress in hot ceilings.

The U.S. Environmental Protection Agency’s LED fact sheets, summarized via ENERGY STAR’s LED technology brief, show typical L70 lifetimes of 50,000–100,000 hours at 25 °C, often dropping to 36,000–60,000 hours at higher temperatures. In practice, a reasonable maintenance factor (MF) is 0.7–0.8 for industrial spaces.

This matches the insight that catalog lumens should be derated by about 20–35% when turning a wattage chart into a long‑term design (IG3).

Design rule:
When using the charts, assume maintained lumens ≈ 0.75 × catalog lumens unless you have project‑specific LM‑80/TM‑21 and cleaning schedules.

1.4 Mounting height and spacing

The charts assume:

• Spacing‑to‑mounting‑height ratio (SMHR) ≈ 1.0–1.5 in open areas.
• Slightly tighter 0.7–1.0 in aisle applications with tall racking.

These ranges align with common industrial practice and the heuristics in ANSI/IES RP‑7 industrial recommendations, which emphasize both horizontal and vertical illuminance on shelves and faces, not just the floor.

Research insight IG1 highlights this: designers often size high bays only on floor foot‑candles, but vertical illuminance on racks and faces usually governs visibility in warehouses and aisles. That is why aisle layouts use closer spacing and narrower optics.

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2. Quick UFO high bay wattage chart by area & height

This section gives you a fast, practical starting point. It assumes:

• UFO high bay efficacy in the 140–160 lm/W range.
• Maintenance factor of 0.75 (lumen derating over life).
• Medium reflectance room (light‑colored walls/ceiling but dusty over time).
• Reasonable uniformity (not a precision photometric layout).

2.1 Legend: how to read the chart

• Area – approximate floor area in square feet.
• Mounting height – distance from floor to fixture (ft).
• Use type – typical application.
• Average target fc – mid‑range of IES‑based recommendations.
• Recommended catalog lumens/fixture – total fixture lumens from LM‑79 test.
• Typical UFO wattage/fixture – assuming 140–160 lm/W.

2.2 Wattage chart (open areas, 12–30 ft mounting height)

Use this chart for open warehouses, gyms, barns, or large garages without tall racking.

Area (ft²)	Mounting height (ft)	Use type (typical)	Target avg fc	Total lumens (initial)	# of fixtures (typical)	Lumens/fixture (catalog)	Suggested UFO wattage/fixture
400–600	10–12	Small garage/shop	30 fc	12,000–18,000	2–4	4,000–6,000	30–60 W
800–1,200	12–14	2‑car shop, bay	30–40 fc	24,000–48,000	3–6	6,000–8,000	40–80 W
2,000–3,000	14–16	Small warehouse	25–30 fc	50,000–90,000	6–10	9,000–12,000	70–100 W
3,000–5,000	16–20	Medium warehouse	25–30 fc	75,000–150,000	8–16	10,000–13,000	80–100 W
5,000–10,000	20–24	Warehouse/arena	25–30 fc	125,000–300,000	12–24	12,000–16,000	100–150 W
10,000–20,000	24–30	Large warehouse	25–30 fc	250,000–600,000	20–40	14,000–18,000	100–150 W

How to apply this chart:

1. Pick your row based on area and mounting height.
2. Use the fixtures count as a starting range.
3. Choose a UFO output in the indicated lumens/fixture band.
4. If the product family publishes an LM‑79 report with higher efficacy, you can use slightly lower wattage for the same lumens.

Expert warning (Pro Tip)
Many retrofits target “equivalent to 400 W/1,000 W HID” labels. Field experience shows this can produce poor uniformity and high glare at 25–35 ft because the HID equivalence is marketing, not a spacing‑verified guarantee (IG2). Always back‑check with lumens and spacing.

2.3 Higher‑illuminance tasks (detail work, assembly, inspection)

For inspection lines, workbenches under high ceilings, or detail manufacturing, you often target 40–60 fc or more. Instead of re‑creating an entire second chart, use this rule:

For 40–60 fc at the same area and height, either:
– Increase fixture count by ~30–80%, or
– Step up one wattage tier (e.g., 100 W → 150 W) and keep spacing similar.

Because industrial guidelines such as ANSI/IES RP‑7 call for higher illuminance and better vertical light for critical tasks, always consider a dedicated task‑lighting layer at benches and machines instead of over‑driving your high bays.

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3. Fast sizing method: step‑by‑step with an example

This section walks through a simple design method you can apply on any project in under 10 minutes.

3.1 Step‑by‑step sizing checklist

Use this checklist as your repeatable method.

1. Define the space

   • Length × width (ft).
   • Mounting height (ft) = ceiling height minus any hanging structure.
   • Surface reflectance: light or dark walls/ceiling? Heavy racking?

2. Choose target foot‑candles

   • Storage aisles: 20–30 fc.
   • General warehouse, gym floor, indoor arena: 25–30 fc.
   • Packing, repair, assembly: 30–50 fc.
     These bands align with the medium‑activity ranges described in IES industrial practice.

3. Calculate total lumens

   • Total lumens = Area × Target fc.
   • Example: 6,000 ft² × 30 fc = 180,000 lumens.

4. Apply maintenance factor

   • Catalog lumens needed = Total lumens ÷ MF.
   • With MF = 0.75 → 180,000 ÷ 0.75 ≈ 240,000 catalog lumens.

5. Pick a fixture output tier

   • Look at available luminaire packages: e.g., 12,000 lm, 18,000 lm, 24,000 lm.
   • Divide catalog lumens by lumens/fixture to estimate fixture count.

6. Check spacing vs mounting height

   • Aim for SMHR ≈ 1.0–1.5 for open areas, 0.7–1.0 for aisles.
   • Adjust count and row spacing to stay inside that band.

7. Verify with photometrics (recommended)

   • Use manufacturer IES files (.ies) in software such as AGi32 to check average fc and uniformity.
   • This is critical for code compliance projects or tight specifications.

3.2 Real‑world example: 6,000 ft² warehouse at 22 ft

Scenario

• 60 ft × 100 ft = 6,000 ft².
• Mounting height: 22 ft.
• General storage and light assembly.
• Target average illuminance: 30 fc.

1) Total lumens
6,000 ft² × 30 fc = 180,000 initial lumens.

2) Maintenance factor
MF = 0.75 → Catalog lumens = 180,000 ÷ 0.75 ≈ 240,000 lumens.

3) Choose luminaire output
Assume a UFO high bay with 16,000 lumens at ~120 W (≈133 lm/W).

Required fixtures ≈ 240,000 ÷ 16,000 = 15 fixtures.

Round to 16 fixtures for clean rows.

4) Layout and spacing

• 4 rows × 4 fixtures = 16 fixtures.
• Row spacing across width: 60 ft ÷ (4 + 1) ≈ 12 ft.
• Fixture spacing along length: 100 ft ÷ (4 + 1) ≈ 20 ft.
• SMHR across width ≈ 12 / 22 ≈ 0.55 (a bit tight, good vertical light on racks).
• SMHR along length ≈ 20 / 22 ≈ 0.9.

This yields a well‑lit space in the 25–35 fc, with good vertical illuminance and minimal dark bands, based on typical UFO distributions.

5) Power and energy

• 16 fixtures × 120 W = 1,920 W connected load.
• At 4,000 hours/year, that is 7,680 kWh/year.
• Compared to a legacy 400 W metal halide layout (about 450 W including ballast) with the same count, that is a reduction from 28,800 kWh/year to 7,680 kWh/year—about 73% energy savings, which is consistent with the 50–70% savings range reported in DesignLights Consortium retrofit case studies.

3.3 Adjusting for bright vs dark interiors

Research insight IG8 notes that a single wattage chart cannot fit all spaces because surfaces act like giant reflectors or sponges for light.

Use these adjustments:

• High‑reflectance spaces (white walls/ceiling, light inventory):
  – You can reduce installed wattage by 10–25% or stretch spacing a bit.
• Dark spaces (black ceilings, dark racks, dark inventory):
  – Plan to increase installed wattage by 15–30% or tighten spacing.
• Heavy racking with tall racks:
  – Consider narrow‑beam optics and SMHR toward the lower end of the range (0.7–1.0), as recommended by industrial best practices in ANSI/IES RP‑7.

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4. Height‑based wattage recommendations

Sometimes you know the mounting height but not the final layout. This section gives you a height‑first rule of thumb and shows where it breaks down.

4.1 Rule‑of‑thumb wattage by mounting height

The table below assumes:

• Medium‑activity warehouse or shop.
• Target 25–35 fc.
• Mid‑range efficacy (~150 lm/W).
• Moderate reflectance walls.

Mounting height (ft)	Typical lumens/fixture	Typical wattage/fixture	Notes
10–12	4,000–8,000	30–60 W	Use wider beam optics; avoid over‑wattage to reduce glare.
12–16	8,000–12,000	60–100 W	Good range for small warehouses and taller garages.
16–20	12,000–18,000	90–150 W	Common “workhorse” zone for UFO high bays.
20–25	18,000–24,000	120–180 W	Suitable for mid‑height industrial bays and arenas.
25–30	22,000–30,000	150–200 W	Use tighter spacing or narrow optics for vertical light.

4.2 Expert warning: when the height rule fails

Research insight IG12 points out a common mistake: at low mounting heights (≤15 ft), people “fix dark spots” by jumping from a 150 W to a 200 W UFO. What actually happens:

• Luminaires are too close to eye level.
• Beam angles are still designed for high‑bay use.
• Result: glare, hot spots, and scalloping on the floor and walls.

In these spaces, a better approach is:

• Use lower‑wattage, wider‑beam fixtures (e.g., 60–100 W) spaced closer together.
• Treat it like an over‑powered shop light grid rather than a traditional high‑bay layout.

If your garage has low ceilings, it can be helpful to compare UFOs with linear options; a deeper discussion of this trade‑off is available in the guide on low‑ceiling garage UFO vs linear lights.

4.3 Thermal environment and wattage choice

Research insight IG14 emphasizes that ambient temperature at the ceiling can significantly impact output and lifetime, even for “high‑bay rated” fixtures. Near roof decks in hot climates, luminaire case temperatures often run much higher than the 25 °C used in LM‑80 tests.

The LED Technology Fact Sheet from ENERGY STAR notes that at elevated temperatures (40–50 °C), L70 lifetime can shrink noticeably compared to 25 °C operation. In practice, that means:

• A fixture advertised at 100,000 hours L70 at 25 °C may effectively behave like a 60,000‑hour product at roof‑deck temperatures.
• You may see faster lumen depreciation, so the maintenance factor should be toward the lower end (≈0.7).

Practical implication for wattage charts:
In hot factories or poorly ventilated metal roofs, favor slightly higher initial lumens or more fixtures at lower drive currents (for cooler operation) instead of pushing a single very high wattage unit.

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5. Linking wattage charts to standards, rebates, and controls

A wattage chart is only the first step. For professional projects, you also need to prove efficacy, safety, and energy code compliance, and often you want to access utility rebates.

5.1 Efficacy thresholds and DLC / FEMP guidance

The U.S. Department of Energy’s FEMP performance criteria for commercial and industrial luminaires publishes minimum lumens‑per‑watt levels for high‑bay/low‑bay products purchased for federal facilities. Many utility programs align with, or are slightly more aggressive than, these thresholds.

DesignLights Consortium (DLC) technical requirements for solid‑state lighting, outlined in their SSL qualification criteria, also set efficacy minimums and require LM‑79 data, LM‑80/TM‑21 documentation, and ANSI C78.377 color compliance. For modern UFO high bays, practical experience shows:

• Standard‑grade offerings often land around 120–150 lm/W.
• Higher‑tier offerings that aim for DLC’s more stringent levels can reach 150–170 lm/W or more.

When your wattage chart calls for a certain lumens/fixture, you can choose:

• A lower‑efficacy fixture at higher wattage, or
• A higher‑efficacy fixture at lower wattage.

From a total cost standpoint, the higher‑efficacy choice usually offers better long‑term ROI and is more likely to qualify for rebates.

Pro Tip – Controls vs undersizing (IG10)
Field projects show that running slightly higher‑wattage fixtures paired with aggressive occupancy and daylight controls often saves more energy and improves safety than undersizing wattage and running them at 100% all day. DLC’s lighting controls guidance backs this up with case studies demonstrating significant additional savings from controls.

5.2 Codes and recommended practices

Energy codes such as ASHRAE 90.1, the International Energy Conservation Code (IECC), and regional standards like California Title 24 all place limits on lighting power density (W/ft²) and require controls such as occupancy sensors and 0–10 V dimming in many commercial spaces.

• The ASHRAE 90.1‑2022 overview describes updated lighting power density targets and mandatory controls for spaces including warehouses and industrial facilities.
• The IECC 2024 commercial energy efficiency chapter further tightens LPD limits and expands daylight and occupancy control requirements.

This means:

• Wattage per square foot from your chart must be checked against local LPD limits.
• Fixtures should support 0–10 V dimming and, where required, integration with occupancy/daylight sensors.

There is a dedicated guide on Title 24 controls for warehouse high bay lighting that walks through control zoning and code triggers in more detail.

5.3 Rebates and ROI

Many North American utilities offer per‑fixture or per‑watt reduced incentives for high‑efficacy, DLC‑listed UFO high bays. To translate the wattage chart into ROI:

1. Use your fixture count and wattage to compute baseline energy savings versus existing metal halide or fluorescent systems.
2. Check the DesignLights Consortium Qualified Products List (QPL) via the DLC QPL search to confirm eligible models.
3. Consult rebate resources such as the DSIRE incentive database or utility‑specific lighting rebate pages to estimate per‑fixture incentives.

In many real‑world projects, total incentives can offset 15–40% of project cost, especially when controls are included.

For a deeper walkthrough on sizing lumens for logistics facilities, including example layouts and safety considerations, see the dedicated warehouse lumens guide for UFO high bay lights.

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6. Common myths about UFO high bay wattage (and what to do instead)

Even experienced contractors and facility managers run into the same wattage‑related pitfalls. This section debunks them and ties back to the charts and methods above.

Myth 1: “Watts per square foot is all you need.”

Focusing only on watts/ft² ignores:

• Efficacy differences (lm/W).
• Mounting height and beam angles.
• Maintenance factor and surface reflectance.

Two designs with the same watts/ft² can produce very different foot‑candles and uniformity. Always start with lumens and target fc, then verify watts/ft² against energy code.

Myth 2: “If it’s DLC listed, the design will be fine.”

Research insight IG11 notes that DLC listing focuses primarily on efficacy and basic performance. It does not guarantee good uniformity, low glare, or correct wattage for a specific room.

For reliable designs, insist on:

• LM‑79 reports for accurate lumen output and color.
• LM‑80/TM‑21 data for lumen maintenance expectations.
• IES photometric files (.ies) to simulate real layouts in tools like AGi32.

Myth 3: “Higher Kelvin always looks brighter, so I can drop wattage.”

Research insight IG13 observes that while 5000 K often feels “crisper,” in industrial spaces with aging eyes, 4000 K with good vertical illuminance can actually be more comfortable at the same foot‑candle level. Chasing “brightness” only by increasing CCT and cutting wattage often leads to complaints about glare and eye fatigue.

A better method is to:

• Hold wattage and layout steady.
• Pick color temperatures that match the work (e.g., 4000 K for mixed tasks, 5000 K for inspection/graphics).
• Focus on uniform vertical lighting rather than over‑cool color.

Myth 4: “One wattage chart works for every project.”

The fast chart in this article assumes medium reflectance, typical dirt levels, and average activity. Research insight IG8 emphasizes that real‑world spaces vary significantly:

• White, clean rooms can outperform the chart with fewer watts.
• Dark racking, smoky or dusty shops, and very high ceilings can underperform.

That is why this chart is a starting point, not a substitute for a full photometric layout on critical projects.

For projects where worker safety and wayfinding are primary concerns—such as forklift traffic or complex racking—consider using the detailed guidance in the article on designing a high bay layout for warehouse safety.

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7. DIY vs professional users: how to use this chart effectively

The same wattage and lumen principles apply to both DIY shop owners and industrial specifiers; they just use them differently.

7.1 For DIY garage and shop owners

Use the chart like this:

1. Measure your floor area and ceiling height.
2. Decide if your space is more like a small garage, 2‑car shop, or small warehouse in the chart.
3. Choose wattage based on the recommended lumens/fixture and mounting height.
4. If you work on detailed tasks (engine work, woodworking joinery, small parts), aim at the higher end of the fixture count or wattage.

A deeper dive into choosing between UFO high bays and other form factors in home shops is available in the guide on mechanics choosing UFO high bays for task lighting.

7.2 For contractors and facility managers

For professional projects, treat this page as a front‑end filter:

1. Use the charts and examples to select one or two candidate wattage tiers.
2. Pull LM‑79 reports, LM‑80/TM‑21 data, and IES files for those tiers.
3. Run layouts in AGi32 or similar, checking average fc, max/min and avg/min ratios, and vertical illuminance on working planes.
4. Cross‑check against ASHRAE/IECC/Title 24 LPD limits and control requirements.
5. Verify DLC listing and local utility rebates before finalizing the specification.

Research insight IG16 underscores that hitting the target average fc is not enough; uniformity ratios often decide whether a space feels safe and pleasant. That is why full photometric verification is essential on anything beyond a simple garage or barn.

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Key takeaways and next steps

• Start with lumens and area, not watts. Use IES‑based foot‑candle targets (20–30 fc for storage, 30–50 fc for active work) to compute total lumens.
• Apply a maintenance factor of ~0.75. Derate catalog lumens by 20–35% to account for aging, dirt, and heat.
• Use height‑based wattage ranges as guardrails, not gospel. Combine mounting height with SMHR (1.0–1.5 open, 0.7–1.0 aisles) to select fixture output.
• Always confirm with photometrics and standards on professional jobs, using LM‑79, LM‑80/TM‑21, and IES files to prove performance.
• Leverage rebates and controls. Pair efficient, DLC‑listed high bays with occupancy/daylight controls to maximize ROI, rather than undersizing wattage.

If you are planning a warehouse, shop, or arena upgrade, use this chart as your first pass to narrow wattage choices, then follow up with a detailed layout and controls strategy tailored to your space.

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FAQ: UFO high bay wattage and lumens

Q1. How many watts of UFO high bay lighting do I need per square foot?
Instead of starting from watts/ft², start from lumens and foot‑candles. For a typical warehouse at 25–30 fc, many efficient designs land between about 0.4–0.8 W/ft², depending on luminaire efficacy and surface reflectance. Use the sizing method in Section 3 to compute lumens and work back to watts.

Q2. How many lumens should a 20 ft ceiling high bay provide?
For 16–20 ft mounting heights in general warehouse applications, a good working range is 12,000–18,000 lumens per fixture, corresponding to roughly 90–150 W at 130–160 lm/W. Exact values depend on spacing, reflectance, and whether you target 25 fc storage or 40–50 fc work areas.

Q3. Do I always need 200 W UFO high bays at 25–30 ft?
Not necessarily. Many modern 150 W high‑efficacy units deliver over 22,000 lumens, which is ample at 25–30 ft in many warehouses when spaced correctly. Reserve 200 W and above for very high ceilings, unusually dark spaces, or where high vertical illuminance is required.

Q4. How does color temperature (4000 K vs 5000 K) affect wattage choice?
Color temperature does not change the measured lumens, but 5000 K can look “crisper” to many people. However, for aging eyes or long shifts, 4000 K with good uniformity often feels more comfortable. Do not cut wattage just because a light is 5000 K; use the same lumens and choose CCT based on visual comfort and task needs.

Q5. When should I involve a lighting designer or engineer?
Bring in a professional when:

• The project must comply with ASHRAE/IECC/Title 24 for a permit.
• There is complex racking, critical safety circulation, or precision tasks.
• You need stamped drawings or a formal energy/rebate submission.

They will take the starting ranges from a chart like this and turn them into a fully validated photometric design.

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Safety & compliance disclaimer
This article is for informational purposes only and does not constitute professional engineering, electrical, or code compliance advice. Lighting designs and electrical installations must comply with applicable standards such as the National Electrical Code (NEC), local building regulations, and energy codes (ASHRAE, IECC, Title 24). Always consult a qualified engineer, electrician, or code official for project‑specific design, verification, and approval.

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Sources

• Illuminating Engineering Society – Industrial Lighting Recommendations
• ANSI/IES LM‑79‑19 – Optical and Electrical Measurements of Solid‑State Lighting Products
• ENERGY STAR – LED Technology Fact Sheet
• DOE FEMP – Purchasing Energy‑Efficient Commercial and Industrial LED Luminaires
• ANSI/IES RP‑7 – Recommended Practice for Lighting Industrial Facilities
• DesignLights Consortium – SSL Technical Requirements
• DesignLights Consortium – Lighting Controls Guidance
• AGi32 – Lighting Analysts Luminaire Documentation