Lux to Footcandle Converter Calculator
Free convert between lux and footcandles for illuminance measurements. Get instant, accurate results with our easy-to-use calculator.
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What are Lux and Footcandles?
Lux (lx) and footcandles (fc) are both units of illuminance - the amount of luminous flux per unit area. They measure how much light falls on a surface.
Lux is the SI unit: 1 lux = 1 lumen per square meter. Footcandles is the imperial unit: 1 footcandle = 1 lumen per square foot. Since 1 m² = 10.764 ft², the conversion is: 1 footcandle = 10.764 lux.
Both units are used in lighting design, with lux being standard internationally and footcandles still common in the United States. They're essential for specifying lighting requirements in building codes and design standards.
Conversion Formulas
Lux to Footcandles
Footcandles to Lux
Conversion factor: 1 footcandle = 10.76391 lux (exact: 1/0.092903)
How to Convert
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1
Lux to Footcandles
Multiply lux by 0.092903: fc = lx × 0.092903
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2
Footcandles to Lux
Multiply footcandles by 10.764: lx = fc × 10.764
Practical Examples
Example 1: Office Lighting
Recommended: 500 lux. Convert to footcandles.
Solution:
fc = 500 × 0.092903
fc ≈ 46.5 footcandles
Example 2: US Building Code
Requirement: 30 footcandles. Convert to lux.
Solution:
lx = 30 × 10.764
lx ≈ 323 lux
Applications
Building Codes
Converting between metric (lux) and imperial (footcandles) requirements in building codes and lighting standards.
Lighting Design
Working with international specifications, converting between measurement systems, and ensuring compliance with standards.
Light Measurement
Converting readings from light meters, comparing measurements from different systems, and standardizing illuminance data.
Education
Teaching unit conversions, understanding illuminance measurements, and learning about lighting science and photometry.
Frequently Asked Questions
Why is the conversion factor 10.764?
1 m² = 10.76391 ft² (exactly). Since illuminance = flux/area, and 1 fc = 1 lm/ft² while 1 lx = 1 lm/m², the conversion is the same as the area conversion: 1 fc = 10.764 lx.
Which unit is more common?
Lux is the international standard (SI unit) and is used worldwide. Footcandles are still common in the United States, especially in older building codes and lighting specifications.
Are there other illuminance units?
Yes, but less common: phot (ph) = 10,000 lux, nox = 0.001 lux. The most common are lux (metric) and footcandles (imperial).
Do lighting standards specify both units?
Many modern standards (like IES) provide values in both lux and footcandles. International standards (CIE) typically use lux. US building codes often specify footcandles.
What are typical illuminance values?
Outdoor daylight: 10,000-100,000 lux. Office: 300-500 lux. Reading: 500-800 lux. Hallway: 100-200 lux. Moonlight: ~0.1 lux. These values are the same whether expressed in lux or footcandles (just different numbers).