What is and is not published
Lightailing store kit pages list power as 'USB 5V or 3xAA battery pack', and BriksMax's USB Power Cable is rated 5V. [1][2] We found no current (amps) or wattage figure on the kit and part listings we read from Lightailing, BriksMax or BRKOX. Without a published wattage, nobody can give an exact running cost for a named kit from published data, so this guide gives you the rate per watt and the formula.
The electricity price comes from the US Energy Information Administration. Its Electric Power Monthly lists the average US residential price at 18.16 cents per kWh for August 2026, a preliminary figure, up from 17.57 cents in August 2025. [3] Your own bill may be higher or lower; use your rate in the formula if you know it.
The formula, and cost per watt
Annual cost = watts x hours per day x 365 / 1,000 x price per kWh. For a USB kit, watts = 5 volts x the current in amps, which you can read with a plug-in USB power meter.
At 18.16 cents per kWh, one watt running 24 hours a day uses 8.76 kWh a year and costs $1.59. The table scales that to 1, 5 and 20 lit sets, assuming each set draws 1 watt, so you multiply by your measured watts per set. [3]
| Lit sets (cost per watt each) | 4 hours a day | 8 hours a day | 24 hours a day |
|---|---|---|---|
| 1 set | $0.27 a year | $0.53 a year | $1.59 a year |
| 5 sets | $1.33 a year | $2.65 a year | $7.95 a year |
| 20 sets | $5.30 a year | $10.61 a year | $31.82 a year |
The ceiling: the most a USB port can cost
A kit cannot draw more than its USB port supplies. Anker's 360 Charger (60W) is a typical multi-port wall charger: six USB-A ports at 5V, up to 2.4A each, 60W in total. Anker says it only supplies the current a device asks for, up to 2.4A per port. [4] That puts a hard ceiling of 12 watts (5V x 2.4A) on any one kit on that charger.
At that ceiling, one set costs at most $3.18 a year at 4 hours a day, $6.36 at 8 hours and $19.09 at 24 hours. Five sets at the ceiling would be $15.91, $31.82 and $95.45. [3][4] These are upper bounds; a kit draws only what it needs, and nothing published says how close any kit comes to 12 watts.
The charger costs a little even with nothing lit: Anker rates standby use at under 0.5W, which is under 4.38 kWh, or under $0.80 a year, at the August 2026 average price. [3][4]
Battery box running cost
Battery-powered kits on the Lightailing store use a 3xAA pack, and batteries are not included. [1][5] Target listed a 24-pack of Energizer Max AA at $17.99 (regular $19.99) on 30 October 2026, about $0.75 a cell. [6] One refill of three cells costs about $2.25, or $2.50 at the regular price.
No kit page we read published battery life, so the cost per hour depends on how long your kit runs on a set of cells. Time it once: note the hours until the lights dim. Then cost per hour = $2.25 / hours per refill.
For comparison, one refill costs as much as about 1.4 watts running from the wall for a whole year at 24 hours a day. [3][6] Even at the 12-watt USB ceiling, 8 hours a day costs at most $6.36 a year, less than three refills. [3][4]
- Measure watts at the USB plug with a power meter, once, with all lights on.
- Annual cost = watts x hours x 365 / 1,000 x your price per kWh.
- Battery cost per hour = price of three cells / hours they last.
- Add the charger's standby draw if it stays plugged in.
Questions before you decide
How much does it cost to run a LEGO light kit for a year?
At the EIA's August 2026 average of 18.16 cents per kWh, each watt costs about $1.59 a year at 24 hours a day, $0.53 at 8 hours and $0.27 at 4 hours. Multiply by your kit's measured watts, because makers do not publish wattage.
How many watts does a LEGO light kit use?
Kit pages list 5V USB or a 3xAA pack but no current or wattage. On a charger such as Anker's 360, with 2.4A per USB-A port, a kit cannot exceed 12 watts, and the charger only supplies what the kit draws.
Is it cheaper to run a light kit on batteries or USB?
A three-cell AA refill cost about $2.25 at Target's 24-pack price on 30 October 2026, the same as about 1.4 watts running all year from the wall at the August 2026 average price. Battery life is not published, so time your own refills.
Sources & verification
Product details and prices can change. Check the linked provider before buying.
- Lightailing light kit for Lewis Hamilton Helmet 43022 (Lightailing line) Accessed 30 Oct 2026
- BriksMax USB Power Cable (V1) Accessed 30 Oct 2026
- U.S. Energy Information Administration, Electric Power Monthly Table 5.6.A (average retail price by sector) Accessed 30 Oct 2026
- Anker 360 Charger (60W), six USB-A ports Accessed 30 Oct 2026
- Lightailing frequently asked questions Accessed 30 Oct 2026
- Target: Energizer Max AA Batteries, 24 pack Accessed 30 Oct 2026
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