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The light level in foot-candles, from a meter or a design requirement.
North American requirements are usually stated as a maintained average — the level the space still holds at the end of the maintenance cycle, after lamp depreciation and dirt. Initial levels run appreciably higher. If the number you have is a design target rather than a measured reading, it is almost certainly the maintained one, and converting it does not change that.
Illuminance
538.2 lx
1 foot-candle = 1 lumen per square foot = 10.7639 lux. Exact by definition. Say whether the level is initial or maintained; the conversion carries neither.
- Foot-candles entered
- 50 fc
- Lux
- 538.2 lx
- Rounded to the nearest metric step of 50 lx
- 550 lx
They open the calculator with your figures already in it
Foot-Candles to Lux Calculator: 538 lx — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
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How this was calculated
Formula source(s)
- NIST SP 811, Appendix B — illuminance: 1 footcandle = 10.76391 lx
- The footcandle is one lumen per square foot; the lux one lumen per square metre (SI Brochure, 9th edition)
Inputs used
- Illuminance (fc)
- 50
Intermediate steps
- Foot-candles entered
- 50 fc
- Lux
- 538.2 lx
- Rounded to the nearest metric step of 50 lx
- 550 lx
Confidence note: 1 foot-candle = 1 lumen per square foot = 10.7639 lux. Exact by definition. Say whether the level is initial or maintained; the conversion carries neither.
Add the equipment this sizes
This result is a specification — 538.2 lx — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.
Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.
Sources checked 2026-09-12 · v1.0.0
Regulatory standards & verification citations2
- NIST SP 811, Appendix B — illuminance: 1 footcandle = 10.76391 lx
- The footcandle is one lumen per square foot; the lux one lumen per square metre (SI Brochure, 9th edition)
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Your workspace
Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.
The direction that matters when the design is American and the equipment catalogue is not. A specification asking for 50 foot-candles on a bench has to be handed to a manufacturer whose photometric data comes in lux, and the conversion is the handover point. The trap on this side is precision that was never there: 50 fc becomes 538.196 lux, and the third decimal on a figure that was a round-number design target to begin with reads as a measurement rather than an intention. The preferred-series row exists to undo exactly that, giving the number back in the shape a metric specification would have written it in the first place.