Enter a device's wattage, how many identical devices you have, and how often you run them. FigureDesk shows total energy used per day, week, month, and year — no electricity rate needed.
Your numbers
Identical devices running the same schedule.
Result
Energy per week
9 kWh
Given 3 × 100 W, 6 h/day, 5 days/week → energy = (3 × 100 / 1000) × 6 × 5 = 9 kWh/week
Energy is power used over time. Multiplying a device's wattage by the hours it runs gives the energy used per use; multiplying by how many identical devices you have and how often you use them extends that to a weekly, monthly, or yearly total — the figure you'd want when sizing a solar array or battery bank, or comparing devices by energy footprint rather than by cost.
energy (kWh/day) = (watts × quantity / 1000) × hours/day
energy/week = energy/day × days/week
Three 100 W lamps, run 6 hours a day, 5 days a week:
This calculator reports energy used (kWh) — no electricity rate required — for one or more identical devices on a flexible weekly schedule. The Electricity Cost Calculator takes that a step further into dollars, using a single device and your own $/kWh rate.
A daily or weekly kWh figure is exactly what a solar array or battery bank sizing calculator wants as input, and it lets you compare devices by actual energy footprint independent of what your particular electricity rate happens to be.
Run this calculator once per distinct wattage/schedule combination, then add the weekly, monthly, or yearly totals together for your combined figure.
No — this only counts the hours you enter as active use. Many devices draw a small standby/phantom load even when "off"; if you want to include that, run this calculator a second time with the standby wattage and the remaining hours in the day, and add the results.
FigureDesk results are advisory and do not replace a licensed electrician, a qualified engineer, or the applicable local electrical code. Verify any electrical work against your local code and with a qualified professional before relying on it.