Electricity Cost Estimator
Estimate your electric bill by appliance — set quantity, hours and days for 15 common devices, enter your $/kWh rate, and see monthly kWh, cost and share.
For scale: US homes average roughly 850–900 kWh/month (EIA) — and heating, cooling and water heat usually dominate. Turn those rows on to see your real shape.
Where it goes — share of your total
What-if comparisons — modeled on your numbers above
Incandescent → LED
Each bulb swapped 60 W → 9 W LED saves 51 W for every hour it's lit.
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Thermostat ±2°F
Rule of thumb ≈3% of heating/cooling energy per °F — modeled on your AC + space-heater rows; varies with climate and HVAC type.
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Old fridge → ENERGY STAR
A modern certified fridge ≈450 kWh/yr (~38 kWh/mo), measured against your refrigerator row.
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How the estimate works
Every row runs the same three-line arithmetic a utility meter runs: watts × hours = watt-hours; ÷ 1,000 = kWh; × your rate = dollars. Multiply a device by how many you have and how many days a month it runs, and the rows sum to a monthly figure. A 1,500 W space heater on for 4 hours is 6 kWh a day — at $0.16 that’s about a dollar a day, which is why heaters show up on winter bills so clearly.
About the wattage numbers — honest ranges, not lab results
Each row pre-fills a typical running wattage with the range printed under the name: a window AC around 1,000 W (small units ~500, large ~1,500), a dryer ~3,000 W per load, a modern 60 W-equivalent LED at 9 W. Two honest caveats:
- Nameplate watts are the ceiling, not the average. Devices with thermostats — fridges, ovens, ACs, water heaters — cycle on and off. The refrigerator row handles this by using a duty-cycled average (~100 W) across 24 hours instead of its ~400 W nameplate; the water-heater row uses its real element wattage (4,500 W) but only ~3 hours a day of actual heating. Both approaches land in the same place — match your own model if you know it.
- Your hours guess matters more than the watts. Doubling the fridge’s wattage changes the bill by dollars; forgetting that the teenager games six hours a night changes it by tens. Estimate hours generously for anything you’re unsure about.
The what-ifs, with their assumptions printed
The three comparison cards recompute live from the rows above. LED swap uses your incandescent count and that row’s own hours. Thermostat ±2°F applies the ≈3%-per-degree rule of thumb to whatever your AC and space-heater rows total — it’s a model, not a measurement, and DOE setback studies land in the same ballpark. Old fridge → ENERGY STAR compares your fridge row against a modern certified unit (~450 kWh/yr); if your row already beats that, the card says so rather than inventing savings.
Deeper reading: watts → kWh → dollars · what uses the most power at home · phantom loads, honestly · how to read your bill.
Everything runs in your browser — the appliances you list are never transmitted, logged or stored.
Frequently asked questions
Is the watt figure what my device actually draws?
It's an honest typical value, not a promise. Nameplate watts are the maximum a device pulls; many appliances cycle on and off (fridge compressors, oven elements) or draw less in normal use. The fridge row already uses a duty-cycled average — that's why its hours stay at 24. For anything else, enter the time it's actually on, and edit the watts to match your nameplate if you know it. A plug-in meter is the only way to know exactly.
How do I find my real electricity rate?
On your bill: effective rate = total amount due ÷ total kWh used. That folds in delivery charges, riders and taxes, so it's more honest than the advertised ¢/kWh. US residential effective rates run roughly $0.10–0.30 — the presets span that range, and reading your bill walks a real statement line by line.
My estimate is lower than my actual bill. Why?
Usually one of three things: the big thermal loads aren't enabled (central HVAC, electric water heat — together often half a bill), your real usage hours are longer than you guessed, or your bill includes fixed fees the per-kWh math can't see. Seasonal swings matter too — a July bill can double a May one.
My AC runs 8 hours but the compressor cycles — do I enter 8?
Yes, roughly. A window AC drawing 1,000 W whose compressor runs ~70% of the time averages ~700 W across the 8 hours — either enter 8 h at 1,000 W and know it errs ~30% high, or enter ~5.5–6 h at 1,000 W for a tighter estimate. The estimator shows the math either way; the error bars on cooling are honest.
What uses the most electricity in a typical home?
Heat and cold, by a wide margin — space heating and cooling together with water heating are commonly half or more of a home's kWh, far ahead of lighting, electronics or any single appliance. The ranked list with real kWh numbers is in what uses the most power.
What's the difference between kW and kWh?
kW is power right now — how fast you're drawing. kWh is energy — power multiplied by time, the unit you're billed for. A 3,000 W dryer running 45 minutes uses 2.25 kWh. The full walkthrough is in watts to kWh.
Do the numbers I enter get sent anywhere?
No. The estimator is one JavaScript file running in this tab — no server does the math, nothing is logged or stored, and the page works offline after it loads. The privacy policy has the details.
Latest articles
What Actually Uses the Most Electricity in a Home — Ranked Honestly
Heating, cooling and hot water quietly own half the average bill — here's the ranked list with real kWh numbers, and where the usual advice is wrong.
Phantom Loads: What Standby Power Really Costs — Without the Hype
Standby draw is worth fixing — but the culprits aren't who you think. Real numbers on which 'off' devices still drink, and which unplugging rituals do nothing.
How to Read Your Electric Bill: kWh, Demand Charges and Fees, Decoded
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Watts to kWh: the Three-Line Math Behind Every Power Bill
One formula prices every device in your home — watts times hours, divided by a thousand. Here's how to run it on anything with a cord.