Appliance energy and electricity cost
Lifestyle tools
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About this tool
Estimate kWh and cost from your appliance watts, daily hours, days, duty cycle and entered flat electricity rate; inspect exact totals and export all rows.
Common uses
- Estimate a household appliance for a chosen number of days using your own electricity rate.
- Sum several entered usage periods and keep unrounded amounts when comparing costs.
How to use it
- 1.Enter your price per kWh and a currency label; add appliance names, watts, hours per day, integer days and duty cycle.
- 2.Calculate and inspect daily and period kWh, each cost, unrounded values and the total; use all 50-row result pages.
- 3.Copy the complete summary or request a protected CSV containing every appliance and the TOTAL row.
Calculated energy examples
A steady load for 30 days
100 W × 5 h/day × 30 days × 100%; illustrative rate 0.20 CU/kWh
daily_kWh=0.5; period_kWh=15; cost=3; total_kWh=15; total_cost=3; displayed_total_cost=3.00 CU
Daily energy is 0.5 kWh, giving 15 kWh and 3 CU over the entered period. The example price is illustrative, not a current tariff.
A cycling load at 25%
200 W × 24 h/day × 30 days × 25%; illustrative rate 0.20 CU/kWh
daily_kWh=1.2; period_kWh=36; cost=7.2; total_kWh=36; total_cost=7.2; displayed_total_cost=7.20 CU
The duty cycle reduces the daily amount to 1.2 kWh; 30 days yield 36 kWh and 7.20 CU.
Round after summing exact costs
Two rows, each 4 W × 1 h/day × 1 day × 100%; illustrative rate 1 CU/kWh
daily_kWh=0.004,0.004; period_kWh=0.004,0.004; cost=0.004,0.004; total_kWh=0.008; total_cost=0.008; displayed_total_cost=0.01 CU
Each exact cost is 0.004 CU and displays 0.00; the exact sum 0.008 rounds to 0.01, so add unrounded values.
Zero duty cycle
100 W × 5 h/day × 30 days × 0%; illustrative rate 0.20 CU/kWh
daily_kWh=0; period_kWh=0; cost=0; total_kWh=0; total_cost=0; displayed_total_cost=0.00 CU
A zero duty cycle gives zero active energy and cost. Standby is excluded unless separately entered.
Limits and notes
- 1–200 appliances; names up to 100 characters, currency label 16. Watts 0–1000000, hours/day 0–24, integer days 1–36600, duty 0–100%, rate 0–10000 per kWh. Up to 6 decimal places; 50 results/page; CSV up to 262144 UTF-8 bytes. Text lengths count UTF-16 code units.
- Use ASCII numbers such as 100 or 0.25, with at most 12 integer digits. No signs, exponent, fractions or grouped numbers. Days must be an integer.
- Duty cycle is the share of the entered hours drawing the entered power. If you enter measured average power, use 100% to avoid counting cycling twice. Standby is excluded unless you add a separate row; avoid overlapping active and standby hours.
- One flat entered rate, with no live pricing, tiered/time-of-use tariffs, fixed fees or taxes. Currency is a label with no conversion. Different row durations are added as entered; the total is not a shared calendar-month forecast.
- Exact decimal arithmetic; energy display rounds half up to 6 places, cost to 2. Totals sum unrounded values before rounding, so displayed row costs may not add to the displayed total. Unrounded values preserve tiny nonzero results. CSV includes all appliances and a TOTAL row, independently of the visible page. Formula-like text is prefixed with an apostrophe; quoted cells and CRLF are used. Saving depends on your browser.
Frequently asked questions
Does this calculate my actual utility bill?
It applies only your single entered rate. Tiered and time-of-use rates, taxes and fixed fees are excluded; no tariff or current price is fetched.
How do I enter duty cycle and standby?
Duty is the share of entered hours drawing the entered watts. Use 100% for measured average power. Add standby as a separate non-overlapping row if needed; the tool does not infer it.
Why can row costs differ from the total when added?
Rows display two-place half-up costs, while the total adds exact unrounded values before rounding. Different day counts are added as their own periods, not a common calendar month. Currency is a label only.