How Much Does It Cost to Run a Grow Tent in the UK? (2026 Guide)
Electricity is the biggest running cost of any indoor grow, and with winter on the way and heaters coming out, it is worth knowing exactly what your setup costs to run. The good news is that it is easy to work out, and a few simple changes can make a real difference to your bill.
The UK electricity price right now
From 1 October to 31 December 2026, the Ofgem energy price cap sets an average electricity unit rate of 26.32p per kWh for households on a standard variable tariff paying by Direct Debit. That rate already reflects the government's temporary removal of VAT from domestic electricity, which runs from 1 October 2026 to 31 March 2027.
Rates vary slightly by region, and if you are on a fixed or time-of-use tariff your price will be different, so check your bill and use your own unit rate in the sums below. The price cap is reviewed every three months, with the next change due on 1 January 2027.
How to work out your running costs
Every piece of equipment has a power rating in watts. To work out what it costs to run:
Watts ÷ 1,000 × hours per day × price per kWh = cost per day
For example, a 480W LED running 18 hours a day uses 0.48 × 18 = 8.64kWh. At 26.32p per kWh that is about £2.27 a day, or roughly £68 over 30 days.
Use the real power draw where you can, not an "equivalent" wattage that some lights advertise. A plug-in energy monitor is the easiest way to measure what your kit actually uses.
What common grow equipment costs to run
Based on 26.32p per kWh and a 30-day month:
| Equipment | Power | Hours a day | Per day | Per month |
|---|---|---|---|---|
| Propagation LED | 52W | 18 | £0.25 | £7.39 |
| LED grow light | 300W | 18 | £1.42 | £42.64 |
| LED grow light | 300W | 12 | £0.95 | £28.43 |
| LED grow light | 480W | 18 | £2.27 | £68.22 |
| LED grow light | 480W | 12 | £1.52 | £45.48 |
| LED grow light | 660W | 18 | £3.13 | £93.80 |
| LED grow light | 660W | 12 | £2.08 | £62.54 |
| HPS light | 600W | 12 | £1.90 | £56.85 |
| Extraction fan | 100W | 24 | £0.63 | £18.95 |
| Clip-on fan | 20W | 24 | £0.13 | £3.79 |
| Tent heater on a thermostat | 150W | About 6 | £0.24 | £7.11 |
| Air pump | 5W | 24 | £0.03 | £0.95 |
Lighting is the big one. Fans and pumps run around the clock but use far less power.
Example: a 1.2m x 1.2m grow tent
A typical 1.2m tent might run a 480W LED, a 100W extraction fan, two 20W clip fans and a small heater on a thermostat in the colder months. At the current rate that works out at:
- 18 hours of light a day: about £102 a month, or about £95 without the heater
- 12 hours of light a day: about £79 a month, or about £72 without the heater
Your own figures will depend on your equipment and how you run it, but this gives you a realistic idea of where the money goes.
LED vs HPS: what's the difference on your bill?
Modern LEDs produce more usable light for every watt than HPS. A good LED gives you the same light, or more, from fewer watts, and puts out less heat, so your extraction does not have to work as hard in summer. Swapping a 600W HPS for a 480W LED on 12 hours a day saves about £11 a month on the light alone at current prices.
When you compare lights, look at efficiency in µmol/J rather than wattage. The higher the number, the more light you get from each unit of electricity. For example, the Maxibright Daylight LED Pro models are rated at 2.7 µmol/J. Read more in our LED vs HPS comparison.
8 ways to cut your grow room running costs
- Choose an efficient LED. Compare µmol/J figures and size the light to your tent. A light that is too big for the space wastes power. Browse our LED grow lights.
- Dim when you don't need full power. Seedlings and young plants don't need 100% output. Running a 480W LED at 75% for 18 hours a day saves around £17 a month.
- Run your lights on a timer. A reliable timer or contactor makes sure lights never run longer than they should. See contactors and timers.
- Control your fan speed. Most extraction fans don't need to run flat out all the time. A speed or climate controller runs the fan only as hard as conditions need. See fan and climate controllers and our guide to choosing an extraction fan.
- Let your lights do the heating. In winter, schedule your light period for the coldest part of the day, usually overnight, so the heat from your lights does some of the work a heater would. Our guide to heating your grow room has more ideas.
- Check for off-peak rates. If you have a smart meter, a time-of-use or Economy 7 tariff can make night-time electricity much cheaper. Running your lights overnight then saves you money twice.
- Keep the heat in. A tent in a cold garage or loft loses heat fast. Raising it off a cold floor and keeping it out of draughts means your heater runs less often.
- Make the most of every watt. Reflective walls bounce light back onto your plants instead of losing it. See reflective sheeting.
Grow tent running cost FAQs
How much does a grow light cost to run per hour?
Divide the wattage by 1,000 and multiply by your unit rate. At 26.32p per kWh, a 300W LED costs about 7.9p an hour and a 600W light about 15.8p an hour.
Is it cheaper to run grow lights at night?
Only if your tariff has a cheaper night rate, such as Economy 7 or a smart time-of-use tariff. On a standard tariff the price is the same all day, but running lights at night in winter can still save you money on heating.
Does a grow tent use a lot of electricity?
A small propagation setup costs very little to run. A larger tent with a 480W to 660W LED adds roughly £45 to £95 a month for the light alone, depending on how many hours a day it runs.
Want a more efficient setup?
Our team can help you choose lighting and ventilation sized for your space, so you are not paying to run more than you need. Call 01744 382 066 or visit us at Unit 5A Rainford Industrial Estate, St Helens, WA11 8LS.