Foot Candle Calculator
Calculate the required lighting in foot-candles for your space based on activity type and area.
What Is a Foot Candle?
A foot-candle (fc) is a unit of illuminance or light intensity, defined as the amount of light reaching a surface one foot away from a source of one candela. In practical terms, 1 foot-candle equals 1 lumen per square foot. It’s a common unit used by architects, lighting designers, and engineers to quantify the brightness of an area.
Foot Candle vs. Lumens
Lumens measure the total light output from a source, while foot-candles measure the intensity of light on a surface. For example, a 1000-lumen bulb will produce a different foot-candle level depending on the room size, ceiling height, and how focused or diffused the light is.
Recommended Foot Candle Levels by Application
- General Indoor (Hallways, Lounges): 5–20 fc
- Reading / Office: 30–50 fc
- Warehouse (Storage): 10–30 fc
- Workshop / Assembly: 75–100 fc
- Garage / Parking: 5–10 fc
- Hospital / Clinical: 50–100 fc
Formula to Calculate Total Lumens Required
Example Calculation
For a 200 sq ft home office requiring 50 foot-candles:
- Total Lumens = 200 × 50 = 10,000 lumens
Why Foot-Candle Measurements Matter
- Ensure workspaces are properly lit to reduce eye strain
- Comply with safety or industry lighting codes
- Maintain visual comfort and even illumination
- Prevent under- or over-lighting that wastes energy
Lighting Standards and Regulations
Organizations such as the Illuminating Engineering Society (IES), OSHA, and ASHRAE provide lighting recommendations in foot-candles for various industries. Retail, healthcare, industrial, and education sectors all have specific guidelines.
Factors That Influence Effective Foot-Candle Levels
- Ceiling height: Higher ceilings reduce light intensity
- Wall color: Dark surfaces absorb more light
- Fixture type: Diffused vs. focused lighting changes coverage
- Light direction: Downlights, uplights, and wall washers affect delivery
- Spacing and layout: Even distribution avoids shadows
Converting Foot-Candles to Lux
If you're using the metric system, 1 foot-candle ≈ 10.76 lux. So, a workspace requiring 50 fc would need about 538 lux.
Types of Fixtures That Deliver High Foot-Candle Output
- LED Panels: Even light distribution, good for offices and clinics
- High Bay Fixtures: Ideal for industrial or warehouse applications
- Track Lighting: Adjustable, directional light for task areas
- Recessed Downlights: Concentrated lighting with beam control
Frequently Asked Questions
What is a good foot-candle level for a home office?
Between 30–50 fc is recommended to support reading and computer tasks without causing eye fatigue.
How many lumens do I need per foot-candle?
1 lumen per square foot = 1 foot-candle. Multiply your desired foot-candle level by the area in sq ft to find total lumens needed.
Are foot-candles and lux interchangeable?
Not directly. 1 foot-candle = 10.76 lux. Lux is used in metric-based lighting calculations.
What happens if I use too few foot-candles?
Areas will appear dim, potentially causing visual discomfort, lower productivity, or safety hazards in workspaces.
Can LEDs provide enough foot-candles?
Yes, modern LED fixtures can be selected to match desired foot-candle levels and are highly efficient for both residential and commercial use.
Do I need a light meter to measure foot-candles?
For exact measurements, yes. But you can also estimate using lumens and square footage with our calculator.
Does fixture height affect foot-candle delivery?
Absolutely. The higher the fixture is mounted, the wider the spread and lower the intensity on surfaces — unless beam angle and wattage compensate.