What Does It Cost to Run?

Your energy bill went up. Find out why before you buy anything.

Compare two bills, measure the appliance you suspect, then choose the smallest fix that fits an older home. No guesses, no impulse buys.

Compare two bills Open the cost calculator

  1. Understand the bill

    See what changed: the rate, the usage, or the number of days.

  2. Measure the thing

    Check how much energy the suspect appliance actually uses.

  3. Choose the smallest fix

    Start with the cheapest step that fits your home, which is sometimes nothing.

Compare bills and find what changed

Bill total, kWh and billing days are the three numbers that separate a price change from a usage change. Example shown.

Nov 2023Nov 2024Change
Total cost$142.36$214.67+51%
Usage739 kWh892 kWh+21%
Billing period30 days30 days0%
Cost per kWh$0.193$0.241+25%

What this pair shows

  • Average cost per kWh rose
  • More electricity was used per day
  • The billing period stayed the same

Rate, usage and days each move the total on their own. Type in your own two bills to see which one moved yours.

Compare your bills

Electricity cost calculator

What one appliance costs to run at your own rate, with the arithmetic shown.

From the label or manual. Cycling appliances need the meter mode instead, except space heaters, which are never metered: use their nameplate as an upper bound. e.g. 1500
e.g. 4
Example rate: $0.20/kWh. Replace it with the per-kWh rate on your bill. e.g. 0.20
Use the billing days printed on your bill, often 28 to 33.

Estimated cost

$0.80per day

$24.00per month

Energy per day
4 kWh
Energy for the period
120 kWh
Cost per day
$0.80

Watts ÷ 1,000 × Hours × Rate 1,000 ÷ 1,000 × 4 × 0.20 = $0.80 per day

    Full calculator with meter mode, fixed charges and worked examples

    Buying guides

    Exact product variants compared by what is in the box, who each suits, and when to buy nothing. As an Amazon Associate I earn from qualifying purchases.

    All buying guides

    Products from our guides

    Exact US packs matched to the manufacturer's record. We do not show prices; check the current offer and seller on Amazon. As an Amazon Associate I earn from qualifying purchases.

    How we choose products

    • Kill A Watt EZ P4460

      Single meter

      You want the same plug-in measurement but with cost shown on the device and readings that survive being unplugged or a power cut.

      Check on Amazon Read the guide
      Amazon link. We may earn a commission.

    • Tapo P115 four-pack

      Four plugs

      You genuinely have four separate plug-in appliances to monitor and want app-based history for all of them.

      Check on Amazon Read the guide
      Amazon link. We may earn a commission.

    • Frost King V73/3H three-window kit

      Three 42 × 62 in. sheets with tape

      You have one to three windows whose cut size, including your kit's margin, fits within a 42 × 62 in. sheet, and a painted wood, metal or vinyl frame.

      Check on Amazon Read the guide
      Amazon link. We may earn a commission.

    • Duck MAX Strength 288070

      Two 62 × 210 in. film rolls, two 0.5 in. × 54 ft tape rolls

      You have many windows, or windows of mixed sizes, and would rather cut film from a roll than fit pre-sized sheets.

      Check on Amazon Read the guide
      Amazon link. We may earn a commission.

    Older-home how-to guides

    Step-by-step help for the problems that come with a house built before you were born.

    All weatherization guides

    • Sourced, not guessed

      Manufacturer manuals, official guidance and the arithmetic on the page.

    • Marked unverified when unsure

      A detail we could not confirm says so, instead of being filled in.

    • Sometimes the answer is buy nothing

      Several guides end by telling you a simpler step makes more sense.

    • Independent and plain about money

      Product links can earn a commission; that never decides what we recommend. How we research