Table of Contents
To convert lumens to watts, divide the light output by the bulb’s efficacy in lumens per watt. Under the EU reference chart, 470 lumens match an old 40 W incandescent bulb, 806 lumens a 60 W and 1,521 lumens a 100 W. A class E LED gives 806 lumens for 6 to 7.3 W.
With LED, counting in watts misleads: two 7 W bulbs can give very different amounts of light, and one 7 W LED replaces an old 60 W bulb. Our guide to choosing LED bulbs covers the cap, the colour temperature and dimming. This page is the conversion reference: the full lumens to watts chart for LED, halogen and CFL bulbs, the formula in both directions, worked values from 200 to 10,000 lumens, the special case of spotlights and strips, and how lumens per watt set the class on the energy label.
Why watts no longer tell you how bright a bulb is
The watt (W) measures power: the electricity a bulb draws. The lumen (lm) measures luminous flux: the amount of visible light it gives out, weighted by the sensitivity of the human eye. The ratio between the two depends entirely on the technology inside the bulb.
When every bulb in the house was incandescent, that ratio barely changed, so “a 60 watt” became shorthand for “a fairly bright bulb”. But a filament turns very little of its electricity into light. Even a halogen bulb, the improved version, manages only about 17 to 24 lumens per watt, while an LED bulb on the mains gives 75 to more than 200.
EU rules have followed. Since 1 September 2021, the packaging of a bulb must show its useful luminous flux in a font at least twice as large as its power, and say whether that flux is measured in a sphere (360°), a wide cone (120°) or a narrow cone (90°). The lumen figure is the one to read first. How much of that light reaches your table is measured in lux, as our guide to lux vs lumens explains.
Lumens to watts chart for LED, halogen and CFL bulbs
This chart comes from Commission Regulation (EC) No 244/2009 on household lamps (Annex II, Table 6). It set the minimum light output a bulb had to reach before its packaging could claim an equivalence with an incandescent bulb, “60 W equivalent” for instance, and that threshold varied by technology. We have added the real power draw of a class E LED, worked out from its efficacy.
| Old incandescent bulb | LED | Halogen | CFL | Power of a class E LED |
|---|---|---|---|---|
| 15 W | 136 lm | 119 lm | 125 lm | 1 to 1.2 W |
| 25 W | 249 lm | 217 lm | 229 lm | 1.8 to 2.3 W |
| 40 W | 470 lm | 410 lm | 432 lm | 3.5 to 4.3 W |
| 60 W | 806 lm | 702 lm | 741 lm | 6 to 7.3 W |
| 75 W | 1,055 lm | 920 lm | 970 lm | 7.8 to 9.6 W |
| 100 W | 1,521 lm | 1,326 lm | 1,398 lm | 11.3 to 13.8 W |
| 150 W | 2,452 lm | 2,137 lm | 2,253 lm | 18.2 to 22.3 W |
| 200 W | 3,452 lm | 3,009 lm | 3,172 lm | 25.6 to 31.4 W |
How to read it: to claim “60 W equivalent”, an LED had to give at least 806 lumens, a halogen 702 and a CFL 741. The last column divides the LED’s lumens by the efficacy of class E, 110 to 135 lm/W. A class F LED, between 85 and 110 lm/W, draws more: up to 9.5 W for the same 806 lumens.
Regulation 244/2009 was repealed on 1 September 2021 by Regulation (EU) 2019/2020, but the equivalence table did not go away: Commission Delegated Regulation (EU) 2019/2015 on energy labelling carries the LED column over in Annex V, Table 7, from 136 lumens for 15 W to 3,452 lumens for 200 W, with linear interpolation between two rows. It now applies to every non-directional light source, whatever the technology: “60 W equivalent” stands for 806 lumens, halogen included. The halogen and CFL columns remain a historical reference.
How to convert lumens to watts, and watts to lumens
The conversion rests on one figure, the luminous efficacy, in lumens per watt: the amount of light produced for each watt drawn. Two formulas follow from it:
- Watts = lumens ÷ efficacy. An 806 lumen LED that produces 120 lm/W draws 806 ÷ 120 = 6.7 W.
- Lumens = watts × efficacy. A 10 W LED at 120 lm/W gives out 1,200 lumens.
Efficacy by type of bulb
- Halogen: about 17 to 24 lm/W;
- Compact fluorescent (CFL): 46 to 75 lm/W;
- LED bulb on the mains: 75 to 217 lm/W, with wide gaps from one model to the next.
The physical ceiling is 683 lm/W, what a source emitting only at 555 nanometres, the yellowish green the eye sees best, would produce. White light mixes every colour and stays well below it: the theoretical limit for a white LED using a phosphor is put at 260 to 300 lm/W.
Rules of thumb, and why to be careful with them
You will often read that you multiply watts by 10 to get lumens. For an old incandescent bulb that underestimates: the chart links 806 lumens to 60 W and 1,521 lumens to 100 W, which is 13 to 15 lumens per watt. For an LED the rule makes no sense at all: a 7 W LED gives 600 to 950 lumens in class F or E.
Another shortcut divides the old wattage by 7 to find the LED wattage. For a 60 W bulb that gives 8.6 W, which assumes an LED of about 94 lm/W, class F. A better bulb needs less. Our advice: forget the shortcuts, read the lumens on the box, and use the watts only to check the fitting’s maximum.
A value between two lines of the chart
For outputs in between, the regulation required linear interpolation between the two neighbouring lines. Take 1,000 lumens, between 806 lumens (60 W) and 1,055 lumens (75 W):
60 + (1,000 − 806) × (75 − 60) ÷ (1,055 − 806) = 60 + 194 × 15 ÷ 249 ≈ 71.7, so 72 W.
The same calculation gives the values people search for most:
| Light output | Old incandescent equivalent | Power of a class E LED |
|---|---|---|
| 200 lm | 21 W | 1.5 to 1.8 W |
| 400 lm | 35 W | 3 to 3.6 W |
| 800 lm | 60 W | 5.9 to 7.3 W |
| 1,000 lm | 72 W | 7.4 to 9.1 W |
| 1,500 lm | 99 W | 11.1 to 13.6 W |
| 2,000 lm | 126 W | 14.8 to 18.2 W |
| 3,000 lm | 177 W | 22.2 to 27.3 W |
| 5,000 lm | beyond the chart | 37 to 45.5 W |
| 10,000 lm | beyond the chart | 74.1 to 90.9 W |
The chart stops at 200 W, or 3,452 lumens for an LED. Beyond that, for floodlights, battens or large ceiling lights, only the efficacy calculation makes sense. How many lumens a room needs is a different question, which depends on its size and use: our guide to office lighting works through one example.
Replacing an old 40, 60, 75 or 100 W bulb
Start from the wattage of the old bulb, read its line in the LED column and choose a bulb that reaches at least that output. The four most common cases, with where we would use them:
- 40 W: 470 lumens, for a wall light, a bedside lamp or a small pendant;
- 60 W: 806 lumens, the usual choice for pendants and reading lamps;
- 75 W: 1,055 lumens, for the ceiling light of a small room;
- 100 W: 1,521 lumens, for the main light of a large room.
If the old bulb was a halogen, use the halogen column: a “60 W equivalent” halogen gave at least 702 lumens, so an 806 lumen LED will be a little brighter.
B22 or E27: the same lumens
The cap makes no difference to the conversion. In the UK, most pendant sets in a ceiling rose take a B22 bayonet bulb, while many fittings made for the European market, including the three shown in this guide, take an E27 or a GU10 bulb. An 806 lumen LED gives 806 lumens in either cap. Our guide to the B22 bulb helps you check which one you have before buying a pack.
The maximum wattage of the fitting still counts
On the page of a light fitting, the watts give the maximum power the lampholder accepts, in real watts. Our minimalist pendant with a black cord and no shade, one of many designs in our bulb pendant light range, takes an E27 bulb of 15 W at most. In a class E LED, those 15 W stand for 1,650 to 2,025 lumens, more than an old 100 W bulb. Respect that limit in real watts, never in “equivalent” watts: a “100 W equivalent” LED draws only 11 to 14 W in class E.
Lumens add up
On a fitting with several bulbs, the sum of the outputs lights the room. A six-bulb E27 ceiling light fitted with six 806 lumen LEDs gives 4,836 lumens for 36 to 44 W in class E: as much light as six old 60 W bulbs, which drew 360 W between them. You will find these multi-bulb designs in our bulb chandelier collection.
One more point affects the light you actually get. Behind a dimmer switch, a dimmable LED gives fewer lumens as you turn it down: choose it on its full output.
Spotlights and LED strips: lumens that compare differently
The lumens to watts chart applies to bulbs that shine in every direction: Regulation 244/2009 covered “non-directional” lamps. Two cases need another reading.
GU10 spotlights
A spotlight concentrates its light into a beam. For these directional sources, EU rules count the useful flux in a cone: 120° if the beam angle reaches 90°, and 90° for a narrower beam. A 350 lumen spotlight sends its 350 lumens where it points, while a standard bulb spreads them all around: on the worktop it is aimed at, the spotlight looks much brighter. So compare spotlights with each other, at the same beam angle. Adjustable heads on spot ceiling light fittings and recessed downlights both use this kind of bulb.
LED strips
A strip is compared in lumens per metre (lm/m). Its wattage per metre says nothing about brightness, but it is what you use to size the driver. Our guide to LED strip lights explains that calculation.
The energy label: from lumens per watt to classes A to G
Since 1 September 2021, bulbs carry the rescaled energy label set by Commission Delegated Regulation (EU) 2019/2015, graded from A to G. Its class is calculated straight from the lumens per watt:
| Energy class | Efficacy of the bulb |
|---|---|
| A | 210 lm/W or more |
| B | 185 to 210 lm/W |
| C | 160 to 185 lm/W |
| D | 135 to 160 lm/W |
| E | 110 to 135 lm/W |
| F | 85 to 110 lm/W |
| G | under 85 lm/W |
For a standard mains bulb, the efficacy is the useful flux divided by the power. For a mains spotlight, it is multiplied by 1.176, since only the flux inside the cone is counted.
From the label to your electricity bill
The label also gives the energy use in kWh per 1,000 hours, a figure equal to the bulb’s wattage: a 7 W LED shows 7 kWh/1000h. To estimate the running cost, multiply the kWh figure by the price of a unit of electricity, shown on your bill. For example, at 25p per kWh, a 7 W LED left on three hours a day uses about 7.7 kWh a year, roughly £2; the old 60 W bulb it replaces used about 66 kWh, roughly £16.50.
A bulb must also match what its box says. If one is clearly dimmer than the output it claims, it is not as described: Citizens Advice explains that the seller is then responsible for a repair, a replacement, a refund or a price reduction under the Consumer Rights Act 2015.
Frequently asked questions about lumens to watts
How many watts is 1000 lumens LED?
A class E LED gives 1,000 lumens for 7.4 to 9.1 W, a class F one for up to 11.8 W. In old incandescent terms, 1,000 lumens sit between the 60 W and 75 W lines of the EU chart, at about 72 W by interpolation.
How bright is 2000 lumens in watts?
About 126 W in an old incandescent bulb, by interpolation between the 100 W and 150 W lines of the EU chart, so more than an old 100 W bulb. A class E LED gives 2,000 lumens for 14.8 to 18.2 W. That output is often shared between two or three bulbs.
What is 5000 lumens in watts?
The EU chart stops at 3,452 lumens for 200 W, so there is no incandescent equivalent. A class E LED gives 5,000 lumens for 37 to 45.5 W. At home, that is about what six 806 lumen bulbs give together, on a multi-bulb fitting or spread across a room.
Is 5000 lumens very bright?
For one room at home, yes: it is close to the light of six old 60 W bulbs. Spread across several fittings, it suits a large kitchen or an open-plan living and dining room. From a single fitting in a bedroom, it would be far too much.
How bright is 10,000 lumens in watts?
A class E LED needs 74 to 91 W for 10,000 lumens, and a class F one up to 118 W. It is the output of a floodlight or of workshop lighting, more than twelve 806 lumen bulbs together, and far beyond what one room of a house needs.
How many lumens per watt is a good LED bulb?
Look at the energy label: from 110 lm/W an LED bulb reaches class E, from 135 lm/W class D, and class A starts at 210 lm/W. Below 85 lm/W it is class G, the same class as an old halogen or CFL bulb.
Sources
- Commission Regulation (EC) No 244/2009, ecodesign requirements for non-directional household lamps, Annex II, Table 6 (rated luminous flux and claimed equivalent incandescent lamp power), repealed from 1 September 2021 by Commission Regulation (EU) 2019/2020 (packaging information for light sources). EUR-Lex
- Commission Delegated Regulation (EU) 2019/2015, energy labelling of light sources, Annex II, Tables 1 and 2 (energy efficiency classes and FTM factors), and Annex V, Table 7 (equivalence claims for non-directional light sources). EUR-Lex
- Lighting advice for householders: LED bulbs, lumens and the energy label. Energy Saving Trust
- Faulty goods: your rights under the Consumer Rights Act 2015. Citizens Advice
- Luminous efficacy, encyclopaedia article (efficacy by type of light source, 683 lm/W maximum, theoretical limit of white LEDs). Wikipedia
Related products
Metal ceiling light with three adjustable spotlights
Minimalist black pendant light with no shade, fabric cable
Industrial black steel ceiling light with 6 exposed bulbs
See also
How to Brighten a Dark Room: Colours, Mirrors and the Right Lighting
Low Ceiling Lighting Ideas: How to Make a Low Ceiling Look Higher
How to Replace a Fluorescent Tube With LED: Wiring Diagrams and Pitfalls
