Electricity cost tools
Appliance wattage calculator
How many watts — and how much money — does a set of appliances use together?
It depends on two things that are usually mixed up: how much power the appliances draw while running, and how many hours a day they actually run. For the four appliances selected here by default — Refrigerator, Gaming PC, Electric oven, Clothes dryer — the running total is 5,950 W if they all draw power at the same instant, but the average across a full day is only 269 W. That average is what turns into 6.47 kWh per day, 196.8 kWh per month and $35.42 a month at $0.180/kWh. Change the list, the wattages or the hours below and every figure recalculates.
Build your appliance list
Heating
1,500 W typical · 8.0 h/day · 100% duty
Cooling
1,200 W typical · 8.0 h/day · 60% duty
Kitchen
120 W typical · 24.0 h/day · 40% duty
Water
3,000 W typical · 24.0 h/day · 27% duty
Utility
1,100 W typical · 8.0 h/day · 100% duty
500 W typical · 24.0 h/day · 50% duty
Electronics
Laundry
Take it from your bill — total charges divided by kWh, not just the energy line.
5,950 W
running watts if every selected appliance draws power at the same instant
196.8 kWh per month, or $35.42 at $0.180/kWh
- Running watts
- 5,950 W
- Average watts
- 269 W
- Startup surge
- 6,600 W
- Energy per day
- 6.47 kWh
Running watts are not what you pay for
Running watts add up the nameplate of every ticked appliance as if they were all on together. Average watts weight each one by how many hours a day it actually runs and by its duty cycle, and that is the figure that becomes 196.8 kWh and $35.42 a month. Here the two differ by a factor of 22.1.
What sets the startup surge
The Refrigerator. One unit of it starting while everything else is already running gives 5,950 W − 150 W + 800 W = 6,600 W, for a fraction of a second. It changes no energy or cost figure on this page.
| Appliance | Watts × qty | Hours/day | Duty | Average watts | kWh/month | Cost/month |
|---|---|---|---|---|---|---|
| Refrigerator | 150 W × 1 | 24.0 h | 35% | 52 W | 38.4 kWh | $6.90 |
| Gaming PC | 400 W × 1 | 4.0 h | 100% | 71 W | 51.7 kWh | $9.31 |
| Electric oven | 2,400 W × 1 | 1.0 h | 35% | 38 W | 27.7 kWh | $4.98 |
| Clothes dryer | 3,000 W × 1 | 1.0 h | 85% | 108 W | 79.0 kWh | $14.22 |
| Total | 5,950 W | — | — | 269 W | 196.8 kWh | $35.42 |
Secondary check: current and apparent power
At 120 V and a power factor of 1, a running load of 5,950 W corresponds to 49.6 A and 5,950 VA. This is a sanity check on the size of the load only. Motor-driven appliances run below a power factor of 1, so their real current is higher than this figure, and nameplate current plus local electrical code — not this page — govern circuit and breaker sizing.
Method
- Per appliance: average W = watts × qty × duty × (hours ÷ 24) + standby W × (off-hours ÷ 24)
- Per appliance: kWh/day = average W ÷ 1000 × 24
- List total running W = Σ (watts × qty) = 5,950 W
- List total kWh/month = Σ per-appliance kWh/month = 196.8 kWh
- Cost/month = 196.8 kWh × $0.180 = $35.42
- Startup surge = running W − one unit's running W + that unit's start surge = 6,600 W
This page sizes and prices a chosen combination of appliances. It does not size circuits, generators or batteries.
Assumptions
- Each appliance is calculated separately by energyEngine-1.2.0 and only then added up, so a row on this page matches its own cost-to-run page for the same inputs.
- Duty cycles and standby draws come from the appliance dataset and are typical values, not measurements of your unit.
- Running watts assume no diversity: everything ticked is treated as on at the same instant.
- The startup surge assumes one motor starts at a time; two identical motors are not assumed to start together.
- Rated power is treated as real power in watts, not volt-amps.
What can change the result?
- Hours per day — the single input that moves monthly cost most.
- Duty cycle for thermostatic appliances, which tracks weather and setpoint.
- Your actual all-in rate per kWh, including fixed and delivery charges spread over your usage.
- Appliance age and efficiency class: two fridges of the same size can differ by a factor of two.
Why the wattage on the label overstates the bill
Most appliance wattage tables stop at the nameplate. A nameplate is a maximum: it tells you what the appliance draws when everything inside it is running at full power. Two things cut it down before it reaches your bill. The first is hours per day — an oven rated at 2,400 W that runs one hour a day contributes far less than a 150 W fridge that is plugged in permanently. The second is the duty cycle: thermostatic and cycling appliances switch their heating element or compressor off for part of the time they are switched on, so a fridge at 35% duty draws its rated power for roughly a third of the time it is powered.
This page keeps those quantities separate rather than blending them into one "typical watts" figure. Running watts answer "how much power is being drawn right now"; average watts answer "what does this cost". They are different numbers and they should not be swapped for each other.
Every row is its own engine call
Each appliance in the table is passed separately through the same energy engine that powers every individual cost-to-run page on this site, and only the results are added up. That is deliberate: it means a row here produces exactly the same kWh and cost as that appliance's own page for the same watts, hours and duty cycle. Nothing is re-derived with a shortcut formula, and no per-appliance figure exists in two versions.
The startup surge shown alongside the totals uses the same one-motor-at-a-time rule as the backup and generator tools. It is a fraction of a second and it changes no energy or cost figure — it is there so that a large number in the specification of a fridge or a pool pump does not get mistaken for a running load.
What this page is, and what it is not
| Page | Question it answers | Main outputs | Deliberately not covered |
|---|---|---|---|
| Appliance wattage calculator (this page) | What does this specific combination of appliances draw, and what does it cost per month? | Running watts, average watts, startup surge, kWh/day, kWh/month, monthly cost, per-appliance breakdown | Whole-house load profiles, circuit or breaker sizing, generator ratings, battery runtime |
| Watts to run a house | How large is my household's total load, and how do running, average and startup differ across it? | Running watts, average watts, startup peak for a household load profile — no cost | Per-appliance cost, hours-per-day editing, equipment recommendations |
Your next decision
- Price a single appliance in more detailSame engine, one appliance at a time, with days per week and standby broken out.
- Move from a list of appliances to a whole-house loadThe household perspective: running, average and startup watts for the loads a home runs, not a chosen list.
- See how long a battery would run these appliancesTurns a load into runtime — the energy storage question this page deliberately leaves out.
- Check generator ratings against a loadContinuous and surge capability tested separately, with the limiting appliance named.
- Why nameplate watts overstate real consumptionThe duty-cycle argument behind the gap between running and average watts.
Electricity cost tools
- Electricity cost calculatorWatts and hours in, cost per day, month and year out.
- Cost per kWh explainedThree different costs per kWh on one bill, and which one belongs in a calculator.
- Watts to run a houseRunning, average and startup watts — separated, not averaged into one range.
- Generator sizeContinuous and surge checked separately, with the limiting load named.
- kWh a house usesBenchmark, bill-derived estimate and bottom-up model, kept apart.
- Normal electricity billDiagnose the bill: is it the kWh or the rate that is unusual?