When planning the lighting for a commercial, industrial, or even residential space, how do you know if it's "bright enough"? The answer lies in a professional measurement called the footcandle.
Using the right amount of light isn't just about aesthetics; it's a critical component of safety, productivity, and comfort. This guide, based on recommendations from the Illuminating Engineering Society (IES) and lighting professionals, will walk you through what footcandles are, why they matter, and how many you need for your specific environment.
What Is a Footcandle?
A footcandle (fc) is a unit of measurement for light intensity. It is the most common unit used by lighting professionals to calculate and describe light levels in businesses and outdoor spaces.
In simple terms, a footcandle measures the amount of light that actually falls on a given surface. One footcandle is equal to one lumen of light density per square foot. It is also technically defined as the illuminance on a one-square-foot surface from a uniform source of light.
The Illuminating Engineering Society (IES) provides recommendations for footcandle levels to ensure adequate illumination and safety for occupants in a wide range of spaces.
How to Read Footcandle Recommendation Charts
When you look at a lighting guide, you'll see a few key terms:
- Average Maintained Footcandles: This is the target average light level for a space.
-
Horizontal vs. Vertical: These terms simply refer to the plane on which the light is being measured.
- Horizontal (Hor): Measures the light landing on a horizontal surface, like a desk, floor, or parking lot surface.
- Vertical (Vert): Measures the light landing on a vertical surface, such as a retail display, shelving, or the face of an ATM.
- General vs. Supplementary Light: For tasks that are very fine or difficult (like "Extra fine" assembly or "Fine" inspection), the high recommended footcandle levels are often achieved by using a combination of general overhead lighting plus specialized, supplementary task lighting.
Recommended Footcandle Levels by Space
While individual applications will always determine the exact levels needed, the following recommendations are the standard for most common areas.
Residential Spaces
Lighting needs vary by room type, as kitchens and bathrooms require more footcandles than living rooms or bedrooms.
- Kitchen (General): 30-40 fc
- Kitchen (Stove & Sink): 70-80 fc
- Bathroom: 70-80 fc
- Home Office: 60-80 fc
- Dining Room: 30-40 fc
- Living Room: 10-20 fc
- Bedroom: 10-20 fc
- Hallway: 5-10 fc
Commercial Offices
- Open Office: 40 fc
- Private Office: 40 fc
- Conference Room: 30 fc
- Lobbies & Reception Areas: 10-20 fc
- Corridors & Stairways: 20 fc (Another guide suggests 25 fc)
- Restroom: 18 fc
Educational (Schools)
- Classroom (Reading, Typing): 20-100 fc (A more specific guide suggests 40 fc)
- Corridor: 25 fc
- Gymnasium (High School): 50 fc
- Library (Stacks, Ordinary Reading): 20-50 fc
- Library (Study & Notes): 20-100 fc
Retail & Grocery
- Department Store (General): 40 fc
- General Retail (Ambient): 50 fc
- Grocery (Circulation Area): 20 fc
- Grocery (General Retail Area): 50 fc
- Merchandising (Self-Service): 200 fc
- Perimeter / Displays (Vertical): 50-75 fc
Warehousing & Storage
- Inactive Storage: 5-10 fc
- Active Storage (Rough, Bulky Items): 10-20 fc (Another guide suggests 10 fc)
- Active Storage (Medium Items): 20 fc
- Active Storage (Fine, Small Labels): 20-50 fc (Another guide suggests 30 fc)
- Picking Stock & Classifying: 20-50 fc
Industrial & Manufacturing
- Assembly (Simple, Large Items): 30 fc (Another guide suggests 20-50 fc)
- Assembly (Medium): 100-200 fc
- Assembly (Difficult, Fine): 100 fc
- Service Garage / Repair Area: 50-100 fc
- Welding (General): 20-50 fc
Exterior & Parking
- Parking Garage (Covered): 5 fc (Another guide suggests 10 fc)
- Parking Lot (Open, Urban, Medium Activity): 1.5 fc
- Parking Lot (Open, Suburban, Medium Activity): 1 fc
- Building Exterior (Safety): 1 fc
- Gas Station Canopy: 12.5 fc
- Automotive Sales Lot (Urban): 20 fc
From Footcandles to Fixtures
Understanding footcandles is the first and most important step to creating a perfectly lit space. It moves you beyond guessing and gives you a professional target for ensuring your room is not just bright, but effective for its purpose.
These recommendations from the IES and other lighting professionals are powerful guidelines to help you plan. Remember that these numbers are a starting point. Final lighting levels can be affected by everything from the height of your ceiling to the color of your paint.
Now that you have the right footcandle targets, the next step is to find the fixtures that get you there. Whether you need 40 fc for an open office or 70 fc for a kitchen, we have the solutions. Explore our full selection of commercial, industrial, and residential lighting to find the perfect fixtures for your project.
