Foot Candle Calculator

Light Meter Reading Checker
Enter your meter reading and space type for an instant IESNA and OSHA compliance verdict

Reading from your light meter at task height

Sets IESNA recommendation and OSHA minimum for your space type

Lighting Audit Result

Your Reading (fc)
IESNA Recommendation
OSHA Minimum
Foot Candles / Lux Converter
Convert between foot candles (US) and lux (metric / international)
10.764
Conversion Factor (fc to lux)

How to Use These Tools

The Light Meter Reading Checker is designed for facility managers and contractors performing a lighting audit. If you are walking a facility with a light meter and want to know whether your readings meet IESNA standards and OSHA minimums for each zone, enter your reading and select the space type. The tool gives you an instant verdict with the relevant benchmarks for that area.

The FC / Lux Converter is a simple unit conversion tool. Foot candles are the standard unit of illuminance in the US. Lux is the equivalent metric unit used internationally. One foot candle equals 10.764 lux. Use this converter when working with international fixture specifications or lighting standards that reference lux instead of foot candles.

How to Take a Foot Candle Reading During a Lighting Audit

  1. Get a Digital Light Meter

    A digital light meter (also called a lux meter or foot candle meter) is an inexpensive tool available from most electrical supply houses. It reads illuminance directly in foot candles or lux. A quality meter runs $30 to $150 and is a standard part of any lighting audit toolkit. Do not try to estimate light levels visually -- human eyes adapt too well to low light to be reliable.

  2. Position the Meter at Task Height

    Hold the meter's sensor facing up at the height where tasks are performed in the space. For offices and classrooms, that is desk height -- roughly 30 inches off the floor. For warehouses and manufacturing floors, it is typically the floor surface or pick height on a rack. For corridors and parking areas, it is floor level. Document the location of each reading so results can be mapped back to specific zones.

  3. Take Multiple Readings Across the Zone

    A single reading in the center of a room does not represent the whole space. Take readings at multiple points -- near each fixture, at the midpoint between fixtures, near the walls, and in corners. Uniformity matters as much as average level. A space averaging 30 fc with dark corners at 8 fc has a problem even if the average passes.

  4. Record and Compare Against Standards

    Enter each reading into the Light Meter Reading Checker above to get an instant verdict against IESNA recommendations and OSHA minimums for that zone. Document all readings on an audit sheet for each area of the facility. Zones that fall below IESNA recommendations are candidates for a lighting upgrade. Zones below OSHA minimums require immediate attention.

Foot Candle Standards by Space Type

The table below shows IESNA recommendations and OSHA minimums side by side -- the same values used in the Light Meter Reading Checker above. OSHA 1910.303 sets legally enforceable minimums for commercial and industrial workplaces. IESNA targets are industry best practice for comfortable, productive, and safe lighting.

Space TypeIESNA RecommendedOSHA MinimumNotes
Office -- General30 fc10 fcOpen office, common areas, hallways
Office -- Task Area50 fc10 fcDesks, workstations, reading areas
Conference Room30 fc10 fcDimmable fixtures recommended
Retail -- General Floor30 fc5 fcAmbient base layer; supplement with accent
Retail -- Display / Accent50 fc5 fcFeature merchandise and display zones
Commercial Kitchen50 fc20 fcHealth code often mirrors OSHA minimums
Classroom30 fc10 fcIESNA RP-3; daylighting integration recommended
Exam / Treatment Room50 fc20 fcHigh CRI (90+) fixtures recommended
Warehouse -- Storage10 fc5 fcLow-traffic storage areas
Warehouse -- Active Picking30 fc10 fcOSHA minimum applies to all active work areas
Manufacturing Floor50 fc10 fcHigher for precision assembly work
Fine Assembly / Inspection100 fc50 fcQuality control and inspection lines
Parking Garage -- General5 fc5 fcIES RP-20; entry zones 50+ fc

Frequently Asked Questions

A foot candle is a unit of illuminance equal to one lumen of light per square foot of surface area. It measures how much light actually arrives at a surface, not how much light a fixture produces. It is measured with a digital light meter held at task height in the space being evaluated. One foot candle equals 10.764 lux, the metric equivalent used internationally.
OSHA 1910.303 sets minimum illumination levels for general industry. Key minimums include: 5 foot candles for storage areas, parking lots, and exit routes; 10 foot candles for general work areas, active warehouses, and corridors; 20 foot candles for commercial kitchens and treatment areas; and 50 foot candles for fine assembly and inspection work. These are minimums -- IESNA recommendations for productive, comfortable lighting are typically two to three times higher than OSHA minimums.
A lighting audit is a systematic assessment of a facility's lighting system. It involves taking foot candle readings in each zone, inventorying existing fixtures, and comparing actual light levels against IESNA and OSHA standards. The audit findings identify opportunities for energy savings, maintenance cost reductions, compliance improvements, and occupant comfort upgrades. Any facility considering an LED retrofit, receiving complaints about light levels, or operating under OSHA jurisdiction should have a lighting audit performed before making changes.
Both measure illuminance -- the amount of light arriving at a surface. Foot candles use square feet as the reference area (1 fc = 1 lumen per square foot). Lux uses square meters (1 lux = 1 lumen per square meter). Because a square meter is larger than a square foot, the same light level always has a higher lux value than foot candle value: 1 fc = 10.764 lux. The US uses foot candles in commercial lighting specifications and OSHA standards. Most of the rest of the world uses lux.
A reading below the IESNA recommendation means the space is under-lit for its intended use. This can affect worker productivity, safety, and comfort -- and in some zones, may also violate OSHA minimums. The next step is to document which zones are deficient and by how much, then consult a lighting contractor about a retrofit or layout modification. FSG performs full lighting audits and retrofit designs for commercial facilities of all sizes. Use the button below to request an audit or contact your local FSG office.
Need to calculate how many fixtures are needed to achieve a target foot candle level? That calculation requires room dimensions, ceiling height, and fixture output -- use our Recessed Lighting Calculator for offices, retail, and healthcare spaces, or the Warehouse and Industrial Lighting Calculator for warehouses, distribution centers, and manufacturing facilities.

Found a lighting deficiency in your facility?

FSG performs professional lighting audits, photometric designs, and turnkey LED retrofit programs for commercial and industrial facilities nationwide. One call covers the audit, the design, and the installation.

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Disclaimer: IESNA recommendations and OSHA minimums shown are based on published standards and are provided for informational purposes only. Specific compliance requirements may vary by jurisdiction, facility type, and applicable codes. Always consult a licensed electrical contractor or certified lighting professional before making lighting decisions based on audit findings.