How to Determine How Many High Bay Lights You Need: A Complete Guide
When it comes to industrial, commercial, or large indoor spaces like warehouses, gyms, or manufacturing plants, high bay lighting is the gold standard. But one question we get asked all the time is: “How many high bay lights do I actually need for my space?”
If you get this wrong, you either waste money on excessive lighting or end up with a poorly lit environment, affecting productivity and safety.
Let’s break this down step by step with all the technical aspects you should consider before making a decision.
What Are High Bay Lights?
High bay lights are designed for spaces with high ceilings, typically ranging from 15 feet (4.5 meters) to 40 feet (12 meters) or more. They’re engineered to provide bright, uniform illumination across large, open areas.
Common high bay light types include:
UFO LED High Bay Lights (circular and compact)
Linear LED High Bay Lights (rectangular, often used in aisles)
Step-by-Step: How to Calculate the Number of High Bay Lights Needed
Step 1: Measure the Area
Get the length and width of your space in feet (or meters) to calculate the total square footage.
�� Formula:
Area = Length × Width
Example: 100 ft × 80 ft = 8,000 sq ft
Step 2: Define the Lighting Requirements (Lux or Foot-candles)
Lighting levels vary depending on the purpose of the space.
Application Recommended Foot-candles
Warehouse (general) 10–30 fc
Assembly area 30–50 fc
Detailed work areas 50–100 fc
Sports complex 50–75 fc
Retail / Showroom 40–60 fc
�� 1 Foot-candle ≈ 10.76 Lux
Step 3: Choose the Right Wattage and Lumen Output
The mounting height of the light determines the required lumen output.
Example estimates:
Mounting Height Recommended Lumens
15–20 feet 10,000–15,000 lumens
20–30 feet 15,000–25,000 lumens
30–40 feet 25,000–35,000 lumens
Most LED high bays offer 130–160 lumens per watt.
Step 4: Use a Lighting Layout or Formula
To estimate manually:
�� Formula:
Number of Fixtures = (Total Area × Desired Foot-candles) ÷ (Lumens per Fixture × CU × LLF)
Where:
CU (Coefficient of Utilization) = ~0.8 for high bays
LLF (Light Loss Factor) = ~0.9 (accounting for dirt, aging, etc.)
� Example Calculation:
Area = 8,000 sq ft
Desired = 30 fc
Fixture = 20,000 lumens
CU = 0.8
LLF = 0.9
Fixtures = (8,000 × 30) ÷ (20,000 × 0.8 × 0.9) ≈ 16.67 → Round up to 17 fixtures
Step 5: Consider Light Distribution and Spacing
Proper spacing avoids dark spots or overlapping. General guidelines:
UFO LED High Bays: Spacing = Mounting height × 1.0 – 1.2
Linear High Bays (Aisles): Follow racking layout
�� Example:
Mounting height = 25 ft → Spacing = 25–30 ft apart in grid
Step 6: Simulate Using Lighting Design Software
For precision, use DIALux, Relux, or Visual Lighting software. This helps create photometric layouts (IES files) and simulate how light will behave in your actual space.
✅ Tips for Optimal Lighting Design
Use reflectors or diffusers for even light spread
Go for IP65+ rated lights in dusty or wet environments
Use motion sensors and daylight harvesting to reduce energy cost
Check for DLC listing and rebates in your area
❓ Frequently Asked Questions (FAQs)
Q1. How high should my ceiling be to use high bay lights?
High bay lights are recommended for ceilings 15 feet or higher. For anything under 15 feet, use low bay or troffer lights
Q2. Can I use UFO high bays in a warehouse with racks?
Yes, but linear high bays are often preferred for aisle lighting because they provide better longitudinal light spread.
Q3. What color temperature is best for high bay lights?
4000K (Neutral White) – Balanced and ideal for warehouses
5000K (Cool White) – Enhances visibility and detail for precision work
Q4. How do I calculate the energy savings of switching to LED high bays?
Formula: Savings = (Wattage Difference × Hours per Year × Number of Fixtures) ÷ 1000 × Electricity Rate
This gives you the annual savings in kWh.
Q5. Should I install dimmable high bay lights?
Yes, especially if you use smart controls or sensors. Dimming improves energy efficiency and extends the lifespan of the fixtures.
Q6. How do I maintain high bay lighting systems?
Schedule periodic cleaning of lenses and reflectors
Replace drivers or modules if lumen output drops significantly
Use IP-rated lights to minimize ingress of dust/water
�� Conclusion
Choosing the right number of high bay lights isn’t just about square footage. It’s about purpose, ceiling height, lumen output, and uniformity. Taking the time to do proper calculations or simulations ensures safety, productivity, and energy efficiency in your facility.
If you’re still unsure, reach out for a free lighting layout design or consultation with a lighting specialist.