Appliance Energy Cost Calculator
The label plate, priced to the day — watts times hours times your rate into the cost of running anything with a plug, and the round-the-clock number the plate hides.
Appliance Energy Cost Calculator
Results recalculate instantly on every keystroke. Nothing you type is transmitted.
What this result does not account for
- Prices the label's running watts — duty cycles are the meter's business
- Watts 1 to 10,000; hours 0.25 to 24; rate 1 to 100¢
In short: A 1,500-watt appliance running 3 hours a day burns 4.5 kilowatt-hours — 81¢ a day at 18¢, $24.30 a month, $295.65 a year. Left running round the clock it would cost $6.48 a day: the plate's watts is a door number, and compressors and thermostats cycle — the meter, not the label, is the truth.
Formula
kWh/day = watts × hours ÷ 1,000; cost = kWh × rate ÷ 100
Every appliance states its appetite on the label in watts, and watts price in three moves: thousands of watts times hours is kilowatt-hours, kilowatt-hours times your rate is money. The honest caveat is duty cycle — a fridge rated 500 watts does not run 24 hours; its compressor cycles, and the label's number is a door, not a day. The clock card prices the label literally so the gap between plate and meter is visible, not assumed.
Worked Example
- Read the watts off the label or the spec sheet.
- Enter the hours it actually runs and your rate.
- Read the day, the month, and the round-the-clock line.
Defaults: 1,500 watts for 3 hours at 18¢ — 81¢ a day, $24.30 a month, $295.65 a year; $6.48 if it never slept.
Strengths & Limits Of This Model
Where this engine is strong
- The label priced to the day, honestly
- The round-the-clock ceiling shown
- One appliance, one honest number
Where it stops
- One appliance per run — the house is a sum of runs
Practical Use Cases
Old-fridge audits
is the garage beast worth it
Space heaters
the 1,500-watt truth
Standby hunting
what never-off costs
Methodology & Editorial Standards
Computation runs in IEEE-754 double precision at full internal precision; rounding to two decimal places occurs strictly at the display layer, so no cumulative drift enters the result. All monetary outputs use accounting presentation — grouped thousands, two decimals, negatives in parentheses — so figures can be transcribed directly into a model or working paper. Division-by-zero and out-of-domain inputs return an em-dash rather than a misleading number.
This engine was reconciled against an independent reference implementation and hand-verified for the worked example above before release. Our full five-stage review process is published on the About Us page.
Disclaimer. This calculator is provided for informational and modelling purposes only and does not constitute financial, tax, legal, medical, or engineering advice. Verify all figures with a qualified professional before acting on them.
Appliance Energy Cost Calculator — 8 Expert FAQs
8 analyst-written answers to the questions practitioners actually ask — optimised for voice and answer-engine retrieval.
How do I calculate an appliance's cost?
Watts times hours divided by 1,000 gives kilowatt-hours; kilowatt-hours times your rate in cents divided by 100 gives dollars. A 1,500-watt heater for 3 hours at 18¢ is 4.5 kWh — 81¢ a day. The page runs the chain for you.
Why is my real bill lower than the label math?
Duty cycle: the label rates the wattage while running, and thermostats stop the run. A fridge rated 500 watts might average a third of that round the clock. The clock card shows the literal label cost — treat it as the ceiling, the meter as the truth.
What does a space heater really cost?
The full 1,500 watts, every hour, no cycling: 81¢ an hour at 18¢ — $19.44 for a round-the-clock cold snap day. Heaters are the honest label case, which is why they dominate winter bills.
What are phantom loads?
The 1-10 watts devices draw while off: TVs, chargers, consoles waiting for a remote. Five watts round the clock is about 2¢ a day — small per device, worth a sweep across the whole house's standby fleet.
How many watts do common appliances draw?
Central AC 3,000-3,500, space heater 1,500, hair dryer 1,500, dishwasher 1,200-2,400 (mostly the water heater), fridge 300-800 while running, TV 60-150, LED bulb 8-15. The label wins over any table — enter what yours says.
Does the rate change the answer that much?
It is the multiplier: the same heater costs 50¢ an hour at 11¢ in North Dakota and $1.85 at 41¢ in Hawaii. Appliance decisions are rate decisions, which is why the same house produces different habits in different states.
Is it cheaper to run appliances at night?
Only on time-of-use plans, where the rate itself moves by the hour — off-peak runs can halve the per-kWh number. The page prices one rate; enter the peak and off-peak rates as two runs to see the spread.
How accurate is the label's wattage?
Honest for its mode, blind to your settings: a microwave's 1,200 watts is full power only. For the real number, a plug-in power meter reads watts and kilowatt-hours directly — the page prices whatever you feed it.