Electricity Cost Live Meter
Watch electricity use and cost increase live from device wattage and your price per kWh. Track Wh, kWh, cost per hour, planned usage, and multiple devices.
Last updated: August 2026
Enter device wattage and an electricity price to start the meter.
Running
Estimated electricity cost so far
Per-device contribution
| Device | Quantity | Total watts | Share | Energy so far | Cost so far |
|---|
Constant-load projections
Constant-power estimate: real devices may cycle, throttle, sleep, or draw less than their rated wattage. Utility taxes, tiered pricing, demand charges, and fixed fees are not included.
All calculations stay in this browser. Currency selection changes formatting only; no FX conversion occurs.
How is electricity use calculated?
Electricity used in kWh = watts × hours ÷ 1,000. The live meter derives included hours from actual timestamps rather than accumulated timer ticks.
How is electricity cost calculated?
Electricity cost = kWh × price per kWh. Paused time is excluded from both energy and cost.
Frequently asked questions
How do I convert watts to kWh?
Multiply watts by usage hours and divide by 1,000.
How do I find cost per hour?
Divide watts by 1,000 and multiply by your entered price per kWh.
Can I include multiple devices?
Yes. Multiple-device mode sums each device's wattage times its quantity.
Is rated wattage the same as actual consumption?
Not always. Devices can cycle, throttle, sleep, or draw less than their label rating.
What does Pause do?
It excludes that time from the energy and cost estimate.
Will a background tab remain accurate?
Yes. The meter recalculates from timestamps when the page becomes visible again.
Limitations and privacy
This is a constant-load estimate. It excludes utility taxes, tiered tariffs, demand charges, and fixed fees. All inputs remain in the browser and are not persisted or sent to analytics.