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Lux to Foot-Candles Converter

Convert between lux (SI) and foot-candles (imperial) for lighting design and compliance.

Interactive calculator

Lux to Foot-Candles Converter

Convert between lux (SI) and foot-candles (imperial). 1 fc = 10.764 lux.

Try an example

Your result will appear here.

Choose a calculation mode, fill in the known values, and click Calculate.

Quick Guide

  • Select Lux → fc or fc → Lux.
  • Enter a value and click Calculate.
  • Use presets for common lighting standards.

Table of Contents

Key Takeaways

  • 1 foot-candle = 10.764 lux exactly (1 lumen per square foot).
  • Lux is the SI standard; foot-candles are used primarily in North America.
  • Office lighting: 300-500 lux (28-46 fc); warehouse: 150 lux (14 fc).
  • IES and OSHA standards often specify illuminance in foot-candles.
  • Both units measure illuminance — light falling on a surface per unit area.

Lux vs. Foot-Candles

Both lux and foot-candles measure illuminance — the amount of luminous flux (light) falling on a surface per unit area. Lux uses square metres (SI), while foot-candles use square feet (imperial). The conversion factor comes directly from the area ratio: 1 ft² = 0.0929 m².

Conversion Formula

fc=lux10.764\text{fc} = \frac{\text{lux}}{10.764}
lux=fc×10.764\text{lux} = \text{fc} \times 10.764

The exact factor is 10.76391 lux per foot-candle, derived from 1 lm/ft² converted to lm/m².

Lighting Standards Reference

Space / TaskLuxFoot-candlesStandard
General office300–50028–46IES
Classroom300–50028–46IES
Retail / showroom300–75028–70IES
Warehouse100–2009–19OSHA
Detailed inspection750–150070–139IES
Photography studio500–200046–186Industry

How to Use

  1. Choose a conversion direction: Lux → fc or fc → Lux.
  2. Enter the illuminance value.
  3. Click Calculate to see the converted value.
  4. Use the “Required Lumens from fc Target” mode for room planning.

Examples

Office at 50 fc

50 fc × 10.764 = 538.2 lux (meets IES office standard)

500 lux to fc

500 / 10.764 = 46.5 fc

FAQ

What is the exact conversion between lux and foot-candles?›

1 foot-candle = 10.76391 lux. This comes from 1 fc = 1 lumen per square foot, and 1 square foot = 0.09290304 m². So 1 fc = 1/(0.09290304) ≈ 10.764 lux.

Why are there two different illuminance units?›

Lux is the SI (metric) unit while foot-candles are based on imperial measurements. The US, particularly in architecture and building codes, still commonly uses foot-candles, while most other countries use lux.

What foot-candle level is required for offices?›

OSHA recommends a minimum of 30 fc (323 lux) for office work. The IES recommends 30-50 fc (300-500 lux) depending on task complexity. Detailed drafting or inspection may require 75-100 fc.

How do I measure lux or foot-candles?›

Use a light meter (lux meter). Most modern meters can display in both units. Smartphone apps can give rough readings but are less accurate than dedicated meters.

Sources

  1. IES Lighting Handbook (11th ed.)
  2. OSHA Illumination Standards (1926.56)
  3. NIST SI Units
Manish Kumar

Author & technical reviewer

Manish Kumar

PhysicsCalcs tools are reviewed with an educational focus: clear formulas, transparent assumptions, and practical context for students and science learners.

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