Watts to kWh: How to Calculate Electricity Use
Convert watts and hours into kilowatt-hours, then calculate electricity cost. Includes worked examples, changing loads, and common unit mistakes.
Make sense of your electricity costs
Find your rate, measure what your equipment uses, and work out whether a change is worth its price.
Understand your bill
How to Find Your Electricity Rate for a Cost Calculator
Find the per-kWh rate to use in an electricity calculator. Separate usage charges from fixed fees with a worked sample bill.
How to Calculate Time-of-Use Electricity Costs
Calculate device costs with peak and off-peak electricity rates. See why an energy-weighted rate matters and how to enter it in a single-rate calculator.
Measure your equipment
How to measure a device’s electricity use
Choose a suitable meter, record cumulative kWh, and calculate average watts.
What does a home server cost to run 24/7?
Compare running costs at different wattages and account for active and idle time.
Gaming PC Electricity Cost: Account for Play, Idle, and Off Time
Estimate gaming PC electricity cost using separate gaming, idle, and off periods. Includes monitors, weekly schedules, and calculator input examples.
Router and Home Network Electricity Cost: What to Count
Estimate a router and home network's running cost. Learn how to include switches and PoE devices without counting the same power twice.
UPS Electricity Cost: Separate the Load from the Overhead
Understand UPS input, output, and efficiency when estimating electricity cost. Includes an overhead example and guidance to avoid double-counting devices.
Decide what to change
Standby Power Cost: Is Switching a Device Off Worth It?
Estimate standby electricity cost, compare groups of devices, and account for a smart plug's own power use before buying one.
When Does Lower Power Use Pay for a Replacement?
Calculate replacement payback from electricity savings. Compare different rates and ownership periods, and handle upgrades with no energy payback.
How we write these guides
Always On Cost explains the calculations behind device electricity costs. Guides are prepared with AI assistance, and worked examples are checked against their stated formulas. We link to primary references for technical definitions and product specifications.
Example wattages, prices, and schedules are illustrative. We do not present them as measured product tests or promises of savings. Use your own readings and tariff for a useful estimate.
There are currently no paid product placements or affiliate links on this site. Manufacturer links are references, not endorsements based on hands-on testing.