maratoolHow to convert lumen-seconds, talbots, and lumen-hours
Type a luminous energy — read lm·s, talbots, lm·min, or lm·h instantly.
Luminous energy is light flux integrated over time — what a camera flash or UV-cure lamp actually delivers. The Luminous Energy Converter handles the second/minute/hour steps exactly.
How it works
- Pick units — "Lumen-hour (lm·h)" to "Lumen-second (lm·s)", or any other pair.
- Type a value — the result updates as you type, with swap and copy.
- Copy — one click, with "Copied!" feedback.
Luminous energy conversion factors
Every unit converts through the lumen-second (the base unit). To convert A → B, multiply by A's factor and divide by B's:
| Unit | = this many lumen-seconds |
|---|---|
| Kilolumen-second (klm·s) | 1,000 |
| Lumen-second (lm·s) | 1 |
| Talbot (T) | 1 |
| Lumen-minute (lm·min) | 60 |
| Lumen-hour (lm·h) | 3,600 |
When you need it
A 1,000 lm bulb running one hour emits 1,000 lm·h = 3.6 million lm·s. A speedlight dumping 60 lm·s does in a millisecond what that bulb does in 60 ms — which is why flashes freeze motion.
Sources & methodology
Conversion factors follow BIPM SI Brochure; exact-by-definition factors are marked in the tool itself. All math runs client-side in your browser — nothing is uploaded.
More conversion guides
- How to convert lumens, kilolumens, and cd·sr
- How to convert lux to foot-candles
- How to convert calories, joules, kWh, and BTU
Or browse everything at once in the new unit & sizing converters roundup.