This electricity cost calculator estimates what it costs to run a device from its watt rating, hours of use, number of days, and your price per kilowatt-hour. Use it to compare appliances, check standby loads, or sanity-check a bill line item before you change habits.
Running cost is often clearer than nameplate marketing. A high-watt device used briefly can cost less than a mid-watt device left on all day. This tool makes that trade-off visible in currency, not only in watts.
Who should use this electricity cost calculator
Renters, homeowners, and small offices use it when comparing space heaters, dehumidifiers, gaming PCs, aquarium gear, or workshop tools. It is also useful when a utility statement lists a blended rate and you want a per-device estimate.
If you manage several devices, calculate each one, then add the costs. Shared circuits and demand charges are outside this simple energy model.
Landlords and facility managers can use the same method to explain why a portable heater policy matters. Show tenants a monthly cost example at the building’s typical rate so the conversation stays numeric rather than anecdotal.
Students in dorms and people in shared housing can estimate a personal device share even when the utility bill is split flat. That will not change the lease, but it clarifies which gadgets dominate.
How to use the electricity cost calculator
- Find device watts on the label, manual, or a kill-a-watt style meter reading.
- Enter realistic hours per day of active draw, not just hours the device is plugged in.
- Enter the number of days in your planning window (often 30 for a monthly view).
- Enter your cost per kWh from a recent bill. Use the energy rate you actually pay, not a national average.
- Read total kWh and estimated cost for that period.
How electricity cost is calculated
Watt-hours accumulate as watts × hours × days. Divide by 1,000 to get kilowatt-hours. Multiply by your rate.
Cost = ((watts × hours/day × days) ÷ 1000) × rate per kWh
Devices with compressors or heaters may cycle. A nameplate max watt is not always continuous draw. Metered average watts produce better estimates when available.
Worked space heater example
A 1,500 W heater runs 4 hours per day for 30 days at $0.15 per kWh.
kWh = (1,500 × 4 × 30) ÷ 1,000 = 180 kWh.
Cost = 180 × 0.15 = $27.00 for the month of use.
| Input | Value |
|---|---|
| Watts | 1,500 |
| Hours per day | 4 |
| Days | 30 |
| Rate | $0.15 / kWh |
| Energy | 180 kWh |
| Cost | $27.00 |
Smaller device check
A 100 W lamp for 5 hours a day over 30 days at the same rate uses 15 kWh and costs $2.25. That contrast helps prioritize which loads matter on a bill.
How Much Does It Cost to Run 60 Watts and Other Devices?
Monthly cost over 30 days at the US average of $0.1816 per kWh. One 60 W bulb costs about 1.1 cents per hour (0.06 kWh × $0.1816).
| Device | Watts | Use | kWh / 30 days | Cost / 30 days |
|---|---|---|---|---|
| LED bulb | 10 W | 5 h/day | 1.5 kWh | $0.27 |
| Incandescent bulb | 60 W | 5 h/day | 9 kWh | $1.63 |
| 60 W bulb left on 24/7 | 60 W | 24 h/day | 43.2 kWh | $7.85 |
| Laptop | 50 W | 8 h/day | 12 kWh | $2.18 |
| TV | 100 W | 5 h/day | 15 kWh | $2.72 |
| Desktop PC | 200 W | 6 h/day | 36 kWh | $6.54 |
| Space heater | 1,500 W | 4 h/day | 180 kWh | $32.69 |
Change the rate field to your own price per kWh and the cost scales in proportion.
Average Electricity Price per kWh (2026)
The average US residential price was 18.16 cents per kWh in August 2026, up from 17.57 cents in August 2025 (EIA Electric Power Monthly, Table 5.6.A). Enter it as 0.1816 if you do not have your own bill. Prices vary a lot by state:
| State | Residential price, Aug 2026 (cents/kWh) | Enter as |
|---|---|---|
| US average | 18.16 | 0.1816 |
| Hawaii | 47.18 | 0.4718 |
| Massachusetts | 30.48 | 0.3048 |
| California | 29.75 | 0.2975 |
| New York | 28.65 | 0.2865 |
| Connecticut | 24.51 | 0.2451 |
| Michigan | 22.99 | 0.2299 |
| Pennsylvania | 21.77 | 0.2177 |
| Ohio | 19.38 | 0.1938 |
| Illinois | 19.32 | 0.1932 |
| Texas | 15.91 | 0.1591 |
| Georgia | 15.90 | 0.1590 |
| Arizona | 15.05 | 0.1505 |
| Florida | 14.99 | 0.1499 |
| Washington | 14.63 | 0.1463 |
| North Dakota | 13.31 | 0.1331 |
| Louisiana | 12.87 | 0.1287 |
| Nevada | 12.72 | 0.1272 |
These are averages that include each state’s typical fees and taxes per kWh. Your own tariff can be higher or lower, so use your bill when you have it.
How to Find Your Price per kWh From Your Bill
Price per kWh = energy charges ÷ kWh used. Example: a bill shows 750 kWh and $135.00 of energy and delivery charges, plus a $15.00 fixed customer charge. The running-cost rate is $135.00 ÷ 750 = $0.18 per kWh; enter 0.18. The all-in average is ($135.00 + $15.00) ÷ 750 = $0.20 per kWh, but the fixed charge is paid even if a device is off, so use 0.18 for one appliance.
Finding a realistic rate and duty cycle
Bills may mix energy charges, delivery fees, and taxes. For planning, use the effective energy price you care about, and note fixed fees separately. For cycling loads, prefer measured average watts over peak nameplate watts when you need accuracy.
Time-of-use plans change the rate by hour. Run peak and off-peak scenarios separately if your hours of use split across periods.
Comparing appliances before you buy
When two refrigerators or dehumidifiers list different watt draws, run each through the same hours and rate. A slightly hungrier unit that runs fewer hours can still win. For always-on network gear, use 24 hours per day so small watt differences show up over a month.
Seasonal loads such as space heaters and window AC units should use the days you actually run them, not a blank 365-day assumption, unless you want an annualized planning number on purpose.
Phantom loads and shared circuits
Wall warts and idle electronics add quiet baseline cost. Group them as one low-watt estimate if you lack individual labels. Shared circuits do not change the energy math, but they can limit how many high-watt devices you can run together without tripping a breaker.
If your goal is bill reduction, rank devices by monthly cost first. Cutting a rarely used high-watt tool helps less than trimming a medium load that runs every day.
EV chargers, HVAC, and large fixed loads
Level 2 chargers and central HVAC dwarf lamp loads. Use nameplate or metered kW carefully, and convert kW to watts (multiply by 1,000) before using this form if your label shows kilowatts. For heat pumps and AC, hours vary with weather, so build a seasonal hours estimate rather than copying a single winter day across the year.
Generators and off-grid inverters introduce efficiency losses. This calculator assumes grid energy at the meter. If you buy fuel for a generator, use a fuel cost tool instead of a kWh rate.
Common electricity cost mistakes
- Using plugged-in hours instead of powered-on hours
- Treating nameplate max watts as continuous draw
- Using a national average rate instead of your bill rate
- Forgetting that monthly fixed fees are not in this formula
- Comparing devices without matching hours of use
Limitations
This is an energy cost estimate for steady inputs. It does not model demand charges, power factor penalties, solar offsets, or inverter losses. Confirm critical purchases with metered readings when possible.
Reading your tariff correctly
Use the energy charge per kWh from your bill, not the total bill divided by days. Fixed monthly fees are separate from running cost.
Comparing appliances
Run two scenarios with different wattages and hours. A heater that runs many hours can cost more than a short high watt spike from another device.
Seasonal use
Winter heating hours and summer cooling hours change the monthly total even when the watt rating stays the same. Update hours when seasons change.
For related unit and percent checks while you plan materials, try the unit converter or the percentage calculator.