How much electricity does an LED bulb use: per hour, day and month (with the maths)

An LED bulb uses little electricity, but a home has dozens of light sources: spotlights, chandeliers, LED strips, track lights. Below you will find the formula, a table per hour, day and month, and worked examples using the real power and luminous flux figures from the product specifications in our catalogue.

How do you calculate how much electricity an LED bulb uses?

Multiply the bulb's power (W) by the number of hours, divide by 1000 to get kWh, then multiply by the price per kWh on your bill.

For the price we used the range from the Romanian energy regulator's (ANRE) comparator, as reported by Antena 3 on 30 September 2026: offers from 1.29 lei/kWh (depending on the region) up to 1.9 lei/kWh, with some suppliers going above 2 lei/kWh. Comparator prices include energy, transmission and distribution charges, green certificates, excise duty and VAT, as explained by Playtech (10 October 2025). Your exact price is on your bill or, in Romania, in the ANRE comparator; elsewhere in the EU, simply use the price per kWh from your own bill.

How much does an LED bulb use per hour, per day and per month?

A 5–15 W LED bulb uses 0.005–0.015 kWh per hour and 0.75–2.25 kWh per month if it is on for 5 hours a day.

Estimate, with the maths: day = W × 5 h ÷ 1000; month = day × 30; cost = kWh per month × 1.29 lei, or × 1.90 lei.

Example for a 10 W bulb: 10 × 5 ÷ 1000 = 0.05 kWh per day; × 30 = 1.5 kWh; 1.5 × 1.29 lei = 1.94 lei and 1.5 × 1.90 lei = 2.85 lei. One hour of use costs 0.01 × 1.29–1.90 lei, i.e. 1.3–1.9 bani (hundredths of a leu). If the bulb is on for 4 hours a day rather than 5, multiply the values in the table by 0.8.

Examples from our catalogue: the G45 E27 LED bulb is 4 W and 350 lm, and the C35 E14 candle bulb is also 4 W and 350 lm. Estimate: 4 × 5 × 30 ÷ 1000 = 0.6 kWh per month, i.e. 0.77–1.14 lei. All bulbs are in our light bulbs collection.

How much do spotlights use?

Estimate: 6 LED spotlights of 7 W, on for 5 hours a day, use 6.3 kWh per month, i.e. 8.13–11.97 lei.

• 6 × 7 W (Round DL058 recessed spotlight, 7 W, 450 lm): 42 W × 5 h × 30 ÷ 1000 = 6.3 kWh; 6.3 × 1.29 lei = 8.13 lei; 6.3 × 1.90 lei = 11.97 lei.
• 6 × 5 W: 30 W × 5 h × 30 ÷ 1000 = 4.5 kWh; 5.81–8.55 lei.
• Spotlights with GU10 bulbs: consumption depends on the bulb you fit. The Reif DL049 spotlight takes a GU10 bulb of up to 10 W; at 10 W, 6 spotlights reach 9 kWh per month (11.61–17.10 lei).

You will find more models, with integrated LEDs or GU10 lamp holders, in our recessed spotlights collection.

How much does an LED chandelier use?

Add up the power of all the bulbs: a chandelier with 5 LED bulbs of 4 W is 20 W and uses 3 kWh per month at 5 hours a day.

• Chandelier with bulbs: the Salinas candelabra has 5 E14 lamp holders. With 5 C35 bulbs of 4 W: 20 W × 5 h × 30 ÷ 1000 = 3 kWh; 3.87–5.70 lei per month.
• Chandelier with integrated LEDs: the Oxley chandelier (small version, 8 lights) is 38 W and 1,192 lm. Estimate: 38 × 5 × 30 ÷ 1000 = 5.7 kWh; 7.35–10.83 lei per month at full brightness. As it is dimmable, it uses less when turned down.

To learn how to choose the size and type of chandelier for each room, see our guide how to choose the right chandelier. For wall lights, the same calculation applies to each fitting; see also our wall lights guide.

How much do LED strips and track lights use?

For an LED strip, multiply the power per metre (W/m) by the length: a 5 m strip at 10 W/m is 50 W and uses 7.5 kWh per month at 5 hours a day.

• 5 m LED strip, 10 W/m (Ideal Lux 120 SMD strip, 1000 lm/m): 50 W × 5 h × 30 ÷ 1000 = 7.5 kWh; 9.68–14.25 lei.
• 5 m LED strip, 5 W/m (the 5 W/m version, 460 lm/m): 25 W → 3.75 kWh; 4.84–7.13 lei.
• Magnetic track with 4 × 12 W fittings (Focus LED TR103, 1000 lm): 48 W → 7.2 kWh; 9.29–13.68 lei. The 5 W version (400 lm) uses less than half: 4 × 5 W = 20 W, i.e. 3 kWh per month.

Strips and tracks run on a power supply (driver), and its losses are not included in the calculation. To find out which components you need for a track system, see our magnetic track guide.

LED vs incandescent or halogen: what should you compare?

Compare lumens (light output), not watts (consumption): an LED bulb gives the same light at a much lower wattage.

EU Regulation 2019/2015 (table 7, EUR-Lex) sets out when a bulb may be described as "equivalent" to an incandescent bulb:

Estimate, LED vs incandescent: the 4 W G45 bulb gives 350 lm, more than a 25 W incandescent (249 lm). Per month, at 5 hours a day: 25 × 150 ÷ 1000 = 3.75 kWh (4.84–7.13 lei), compared with 0.6 kWh (0.77–1.14 lei) for the LED.

Estimate, LED vs halogen: for mains-voltage PAR16 reflector halogen spotlights, the same regulation (table 4) gives a reference of 300 lm (in a 90° cone) for 50 W. Six 50 W halogen spotlights use 45 kWh per month (58.05–85.50 lei), compared with 6.3 kWh for six 7 W DL058 LED spotlights at 450 lm each. The fluxes are declared differently, so the comparison is only indicative.

Energy-saving bulbs (compact fluorescents) are compared the same way: look at the lumens and divide by the watts.

How do you read a bulb's energy label?

The label shows the efficiency class (A–G), consumption in kWh per 1000 hours and a QR code linking to the European EPREL database.

• The class is calculated from lumens divided by watts (lm/W), with a correction factor for the type of source: class A requires at least 210 lm/W, while G means under 85 lm/W, under EU Regulation 2019/2015 (Annex II), applied since 1 September 2021.
• kWh/1000 h is effectively the bulb's wattage: a 7 W fitting uses 7 kWh in 1000 hours (7 × 1000 ÷ 1000).
• Example: the DL058 spotlight gives 450 lm at 7 W, roughly 64 lm/W, and is class G in the product specification. A class G rating on an LED doesn't mean high consumption, just that the scale is strict.

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