Everyday Calculators
Use this appliance wattage calculator to estimate what a device costs to run from its wattage and daily use.
Live calculator
2.4 kWh per day.
At 18 cents per kWh.
Monthly cost multiplied by 12.
Watts show how much power an appliance draws while running. Electric bills charge for energy, so this calculator converts watts and hours into kilowatt-hours.
Power multiplied by time and converted to kWh.
| Measure | Estimate |
|---|---|
| Daily kWh | 2.4 kWh |
| Monthly kWh | 72 kWh |
| Daily cost | $0.43 |
| Monthly cost | $12.96 |
Utility estimates depend on local rates, fixed fees, taxes, runtime, billing period, and household usage. Compare against the actual bill before settling up.
Quick answer
Appliance Wattage Calculator calculates appliance energy cost from watts, quantity, hours per day, days per month, and electricity rate. The visible formula is kWh = watts x quantity x hours / 1000; cost = kWh x electricity rate.
Formula
kWh = watts x quantity x hours / 1000; cost = kWh x electricity rateActual use can be lower than nameplate wattage when appliances cycle on and off.
How to use
Example
Calculator use
Before relying on it
Details
These notes make the assumptions explicit, especially where the same search query can mean slightly different things.
Watts describe how much power the device uses while running at that setting.
Electric bills use energy over time, so watts are multiplied by hours and divided by 1,000.
Refrigerators, HVAC, dehumidifiers, chargers, and heaters may cycle or change power levels during use.
Benchmarks
The calculator is a decision aid, not a fixed rule. Use the output to compare scenarios and document your assumptions. Benchmark ranges are broad planning heuristics unless this page names a specific source for the range.
Common for LED lights, chargers, fans, and efficient electronics.
Common for heaters, microwaves, hair dryers, kettles, and some kitchen appliances.
Even a modest wattage can matter if it runs for many hours every day.
Calculator accuracy
The formula, inputs, example, and limitations are shown so the result is checkable, not just a number in a box.
kWh = watts x quantity x hours / 1000; cost = kWh x electricity rate
Watts, Quantity, Hours per day, Days per month, Electricity rate
Utility pages use visible usage and rate assumptions. Actual bills may include tiers, service fees, delivery charges, taxes, minimums, seasonal rates, and provider-specific rules.
June 6, 2026
Toolkit Shelf. Appliance Wattage Calculator. Last reviewed June 6, 2026. https://toolkitshelf.com/tools/appliance-wattage-calculator
FAQ
Multiply watts by hours used, then divide by 1,000. For cost, multiply kWh by your electricity rate.
Check the appliance label, manual, product page, or a plug-in energy meter. Some labels show amps and volts instead of watts.
Many devices cycle, change modes, or use less than rated wattage during normal operation. Utility rates and fees also vary.
Match the result to the task type: shopping tools depend on the same unit and usable quantity, home-project tools depend on field measurements and waste, date/time tools depend on counting rules, and conversion tools depend on the unit system.
Round for readability after checking the formula and units. Keep more precision when the result feeds another calculation, and add a task-specific buffer only when shortage, waste, or timing risk matters.
Different tools may use different rounding, assumptions, default rates, methods, formulas, or input timing. Compare the visible method and inputs before relying on the output.