ToolNestFree Electricity Cost Calculator
Last updated: October 22, 2026
Quick answer: A space heater and an LED bulb can both be 'on' for hours, but one costs about 150 times more to run — and the difference is just watts times hours times your electricity rate. This free electricity cost calculator turns any appliance into dollars: enter its wattage, hours per day, and your price per kWh, and it shows the kWh and cost per day, week, month, and year, with presets for the appliances people ask about most — fridge, TV, gaming PC, space heater, air conditioner, dryer, water heater, and EV charger. Everything runs in your browser; nothing is uploaded.
Formula: kWh per day = (watts ÷ 1,000) × hours per day × duty cycle × quantity. Cost = kWh × rate. Month = daily × 30, year = daily × 365. The default rate, 18.31 cents/kWh, is the US residential average (EIA, July 2026) — replace it with the rate on your own bill for an exact figure, since delivery charges, taxes, and tiered pricing sit outside the energy rate. Wattages are typical values; check the label on your appliance. Appliances that cycle (fridges, air conditioners) do not draw full power continuously — use the duty-cycle field or the preset's cycling value.
✓ Free forever · ✓ No signup · ✓ Tool inputs stay in your browser — never sent to our servers.
How to Use the Electricity Cost Calculator
- Pick an appliance preset to fill in typical watts and hours, or enter your own numbers from the appliance label — watts are printed on the back, bottom, or power adapter of most devices.
- Enter your electricity rate in cents per kWh from your bill. If your bill only shows a total, divide the total amount due by the kWh used that month for an all-in rate.
- Set the duty cycle if the appliance cycles on and off: a fridge rated 150 W that runs about a third of the time is 33%, not 100% — the preset handles this for you.
- Click Calculate cost to see kWh and dollars per day, week, month, and year, plus the cost per hour of running it.
- Compare before you buy or replace: run the old appliance and the new one through the same rate and hours, and the yearly difference is the payback math for the upgrade.
Why Use Our Electricity Cost Calculator?
- Day, week, month, and year costs — one input gives all four horizons, so a $2-a-day habit and a $65-a-month bill are the same number, seen both ways.
- Common-appliance presets — fridge, TV, gaming PC, space heater, air conditioner, dryer, water heater, and EV charger with typical watts and hours pre-filled.
- Duty-cycle support — cycling appliances (fridges, AC units, heaters with thermostats) cost far less than their nameplate watts suggest; the duty field models that honestly.
- Your own rate, not a guess — the US average (18.31¢/kWh) is only the default; entering your bill's rate makes the result exact for your utility.
- Quantity multiplier — ten LED bulbs, two space heaters, or a bank of monitors: scale the result without retyping.
- 100% client-side — your rate and usage never leave your browser; no signup, no account.
Common Use Cases
- Deciding whether to replace an old appliance: Run the old fridge (say 250 W at 50% duty) against a new one (150 W at 33%) at your rate: the yearly difference is the real payback period for the purchase price, not the marketing claim.
- Explaining a high bill: Plug in the space heater, the dryer, and the water heater at your household's actual hours — one of them usually explains the spike, and knowing which one stops the argument about who left the lights on.
- Sizing a home battery or solar offset: Add up the daily kWh of the loads you want to cover (EV charging alone can be 28.8 kWh a day) before sizing a battery — the calculator's daily kWh figure is the input solar and battery quotes are built from.
- Landlord and renter cost splits: When a rental includes a heater, a dryer, or an EV charger on a shared meter, the per-appliance monthly cost gives a defensible split instead of a flat guess.
Electricity Cost Calculator vs Alternatives
- EverydayTools' electricity cost calculator: A strong niche tool with time-of-use peak/off-peak rates and a detailed appliance table — the most complete free option for tariff nerds. Ours is the faster answer: watts, hours, rate, duty cycle, and all four horizons on one screen.
- WattItWillCost.me: A clean single-purpose calculator with a big typical-wattage table and volts × amps support. Ours adds the duty-cycle field for cycling appliances, quantity scaling, and copyable summaries.
- Your utility's bill breakdown: Authoritative for your total, and the only source for your exact tariff — but it won't tell you what one appliance costs. Use the bill for your rate, this calculator for the per-appliance split.
- A smart plug with energy monitoring: The ground truth for one device's actual draw, and the right way to settle a disputed wattage. It costs money per plug and measures one outlet at a time; use the calculator for every other appliance and the plug for the one you can't pin down.
Bottom line: your utility bill tells you the total, a smart plug tells you one device exactly, and the tariff-focused tools tell you the most about rates. For the everyday question — 'what does this appliance cost me to run?' — watts, hours, rate, and duty cycle on one page is the whole job, and this page does it free.