Why you can't just match the watts
With old incandescent bulbs (or globes), wattage doubled as a brightness label — a 100W bulb was clearly brighter than a 40W one. But watts only ever measured energy use, not light. LEDs produce the same brightness for a fraction of the energy, so a 10-watt LED can be every bit as bright as an old 60-watt incandescent. That's why, when you shop for LEDs, you should compare lumens (brightness) rather than watts.
In other words, there's no fixed "watts to lumens" formula. The reliable way to convert is to use the brightness each old wattage was known for, which is what the table below gives you.
Watts to lumens conversion table
Approximate brightness of a traditional incandescent bulb at each wattage, and the LED wattage that usually matches it:
| Old incandescent | Approx. lumens | Matching LED wattage |
|---|---|---|
| 15W | 140 lm | 2–3W |
| 25W | 250 lm | 3–4W |
| 40W | 450 lm | 4–6W |
| 60W | 800 lm | 8–12W |
| 75W | 1,100 lm | 10–14W |
| 100W | 1,600 lm | 14–18W |
| 150W | 2,600 lm | 22–26W |
| 200W | 3,500 lm | 28–34W |
These are approximate — efficiency varies between brands, so always check the lumens printed on the box.
How many lumens is a 40-watt bulb?
A 40W incandescent bulb gives about 450 lumens. Match it with an LED rated around 450 lm (roughly 4–6W of LED power). Good for a lamp, hallway or a softly lit bedroom.
How many lumens is a 60-watt bulb?
A 60W incandescent bulb gives about 800 lumens — the most common household brightness. Look for an LED around 800 lm, which usually draws just 8–12W. This is the sweet spot for most living-room and bedroom fittings.
How many lumens is a 75-watt bulb?
A 75W incandescent bulb gives about 1,100 lumens. Match it with an LED around 1,100 lm (about 10–14W). A good level for kitchens and larger rooms.
How many lumens is a 100-watt bulb?
A 100W incandescent bulb gives about 1,600 lumens — bright, room-filling light. Match it with an LED around 1,600 lm, typically 14–18W. Ideal for kitchens, workspaces and living areas that need to be well lit.
Lumens to watts: the other direction
Shopping the other way round — you know the lumens and want the old-bulb equivalent? Just read the table in reverse: 800 lm ≈ an old 60W bulb, 1,100 lm ≈ 75W, and 1,600 lm ≈ 100W. If a box only lists LED watts, remember an LED uses roughly a fifth to a tenth of the old wattage for the same light.
How to use your result
The calculator gives you a small lumen range rather than a single number, because the ideal brightness depends a little on the room and your taste. If your old bulb felt too dim or too bright, tell us and we'll shift the range up or down accordingly. Once you have your lumen target, pick a colour temperature to suit the room and match your fitting.
Want the full recommendation — brightness, colour, fitting and finish in one go? Try the bulb finder. To understand the science, read what are lumens?, and to choose the light colour see warm white vs cool white.
Frequently asked questions
Is watts or lumens more important for brightness?
Lumens. They measure the light a bulb actually gives out, so they're the true brightness figure. Watts only tell you the energy it uses — which matters for your power bill, not for how bright the room feels.
Why do LEDs list a "60W equivalent"?
Because most people still think in old-bulb watts. "60W equivalent" is shorthand for "about 800 lumens" — the brightness a 60W incandescent used to give. Check the actual lumen figure to be sure, as "equivalent" claims vary between brands.
Do LED watts convert to lumens the same way?
No — LEDs are far more efficient, so their watts are much lower for the same light. Use the LED wattage column in the table above as a guide, but always buy by lumens.