Candela to Lux Converter
Enter luminous intensity (cd) and distance (m) to instantly calculate illuminance in lux using the inverse square law.
Candela to Lux
Candela — how bright the source is in this direction
Distance from source to the lit surface in meters
Angle between light ray and surface normal (Lambert cosine law). Leave at 0 for perpendicular incidence.
Required illuminance at the surface in lux
Enter values to see the result
Illuminance
—
lux (lx)
Typical Illuminance Levels
| Setting | Lux |
|---|---|
| Moonlit night | 0.1 |
| Street lighting | 10 |
| Corridor / hallway | 100 |
| Office / reading | 300–500 |
| Surgery / inspection | 10 000+ |
| Full sunlight | 100 000 |
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Summary
Enter luminous intensity (cd) and distance (m) to instantly calculate illuminance in lux using the inverse square law.
How it works
- Enter the luminous intensity of the light source in candela (cd).
- Enter the distance from the light source to the surface in meters.
- The tool calculates illuminance using the formula: lux = candela / distance².
- Results update instantly as you type.
- Use the reverse mode to find required candela for a target lux level.
Use cases
- Determine illuminance at a given distance from a spotlight or lamp.
- Verify compliance with workplace lighting standards (lux requirements).
- Plan stage or architectural lighting setups.
- Calculate reading light intensity at desk height.
- Estimate outdoor lighting coverage from floodlights.
- Cross-check photometric data from manufacturer spec sheets.
Frequently Asked Questions
Last updated: 2026-06-10 ·
Reviewed by Nham Vu