Grow light energy use: calculate the cost

Calculate electricity cost from actual power consumption, hours of use and your tariff. Enter your figures; there is no universal rate or guaranteed saving for every setup.

The basic formula

Energy in kWh = watts ÷ 1,000 × hours per day × number of days. Cost = energy in kWh × your tariff per kWh. Add ventilation, humidification and other equipment separately if you want to estimate the whole setup.

Your calculator

Compare like-for-like setups

Use power consumption at the socket for the setting you actually use, not a stated “equivalent” wattage. A LED/HPS comparison should also consider coverage, the function provided and additional equipment. Savings cannot be inferred from the technology name alone.

To choose a format, see the use-based comparison and indoor plant lights. The guide to comparing two budgets distinguishes electricity costs from purchase costs.

Editorial review: 3 October 2026 · TerraLED. Set up your equipment according to its instructions and the needs of the species.