Financial calculator category
Energy & Utilities calculators
Price appliance electricity, EV charging and fuel economy, and size a battery for a load. 8 calculators here — Electricity Cost Calculator, EV Charging Cost Calculator and MPG Calculator among them — each showing its formula, a worked example, and its sources.
Compare scenarios, not just answers
Start with values you can verify, save a baseline and change one assumption at a time. Formula, worked example, interpretation boundary and authoritative reference are on every calculator below.
Electricity Cost Calculator
Calculate the kilowatt-hours and cost of running any appliance from its wattage, hours and your rate.
Open calculator →02EV Charging Cost Calculator
Estimate monthly charging cost and cost per mile for an electric vehicle at home rates.
Open calculator →03MPG Calculator
Calculate miles per gallon, fuel cost per mile and liters per 100 km from a fill-up.
Open calculator →04Battery Runtime Calculator
Estimate how many hours a battery can run a load from its amp-hours, voltage and usable share.
Open calculator →05Solar Panel Output Calculator
Estimate a solar array's daily and yearly energy from panels, wattage, sun hours and losses.
Open calculator →06Solar Payback Calculator
Estimate the payback period and 25-year net savings of a solar system after incentives.
Open calculator →07LED Bulb Savings Calculator
Calculate yearly electricity savings from swapping older bulbs for LEDs.
Open calculator →08Generator Size Calculator
Estimate the generator wattage needed from running watts and the largest starting surge.
Open calculator →Go deeper
Energy & Utilities guides
Every tool, one table
Energy & Utilities calculators at a glance
Each row shows the headline figure that calculator returns at its own worked-example inputs, so the whole category is comparable before you open anything.
| Calculator | What it answers | Headline output | Worked example |
|---|---|---|---|
| Electricity Cost Calculator | Find which appliance is worth replacing by pricing its running cost per month and per year. | Cost for the period | $61 |
| EV Charging Cost Calculator | Compare the monthly charging cost with what you spend on gasoline today. | Charging cost per month | $57 |
| MPG Calculator | Track real mileage against the sticker figure by measuring one full tank to the next. | Miles per gallon | 28 |
| Battery Runtime Calculator | Size a battery bank for an RV, a workshop or a backup power supply before you buy it. | Runtime | 4.8 hours |
| Solar Panel Output Calculator | Compare a proposed system's production against what your household actually uses. | Energy per day (kWh) | 31 |
| Solar Payback Calculator | Test a quote by checking how long the savings take to repay what you spend. | Simple payback | 8.2 years |
| LED Bulb Savings Calculator | Rank the rooms worth relamping first by how many hours their lights stay on. | Savings per year | $190 |
| Generator Size Calculator | Size a portable generator so a starting motor does not trip it. | Minimum generator size (watts) | 5,000 |
These are example results at each calculator’s default inputs: open any calculator above to try your own numbers. The energy & utilities figures here come from each calculator’s own published formula, so any result can be traced back to its inputs, and a result that looks surprising is more often a sign that an assumption needs changing than that the arithmetic is wrong.
Background reading
Energy & Utilities guides
- How to size a backup generatorBuild an essential-load list, separate running watts from starting surge and choose a generator, battery or both without buying too big or too small.
- How to work out what an appliance costs to runTurn a wattage label, the hours of use and your electricity rate into a monthly and yearly cost, then decide which changes are worth making.
- Comparing fuel economy: mpg, L/100 km and electric carsConvert between fuel economy units, measure your real mileage and compare gasoline and electric cars on cost per mile.
Keep exploring
Related calculator categories
Next to the energy & utilities tools, these categories answer the questions that usually come up alongside them.
People also ask
Energy & Utilities calculator questions
What can I calculate in the energy & utilities category?
8 calculators: Electricity Cost Calculator, EV Charging Cost Calculator, MPG Calculator, Battery Runtime Calculator, Solar Panel Output Calculator, Solar Payback Calculator, LED Bulb Savings Calculator, Generator Size Calculator. Price appliance electricity, EV charging and fuel economy, and size a battery for a load.
Are the energy & utilities calculators free?
Yes. Calculators run in your browser. No account, no sign-up, no gated result. Inputs are not sent to a server, and each page shows its formula, a worked example, limitations and its sources.
How accurate are these energy & utilities estimates?
The arithmetic follows each published formula and is tested at normal and boundary values. Accuracy for a real decision depends on your inputs and on whether fees, rules or timing fall outside the model. Interpretation boundaries are stated on the page.
Which energy & utilities calculator should I start with?
Start with the one matching the decision you face. For example, the Electricity Cost Calculator returns cost for the period of $61 at its worked-example inputs. Each page links the related calculators that answer the next question.
Which energy & utilities calculator asks for the fewest inputs?
Generator Size Calculator asks for 2. The most any energy & utilities calculator asks for is 5 (Solar Payback Calculator and LED Bulb Savings Calculator), and the middle calculator takes 4.
Which energy & utilities calculator asks for the most inputs?
Solar Payback Calculator asks for 5: system cost before incentives, tax credit or incentive, annual production (kwh), electricity price per kwh and yearly output decline. Expect to gather more documents for it than for Generator Size Calculator, which asks for 2.
Which input decides the result most often across the energy & utilities calculators?
Electricity price per kwh moves the headline result most in 3 of the 8 energy & utilities calculators tested, including EV Charging Cost Calculator, Solar Payback Calculator and LED Bulb Savings Calculator. Each was measured by moving one input at a time from its worked-example value and comparing the change in the headline result.
What kind of result do the energy & utilities calculators return?
Of the 8 energy & utilities calculators, 3 return a dollar amount as the headline result, 3 return a plain number as the headline result, 1 returns a number of hours as the headline result and 1 returns a length of time in years as the headline result. Every one also shows 2 to 3 results in total.
What do the energy & utilities calculators ask you to enter?
Across the 8 energy & utilities calculators there are 31 input fields: 20 plain numbers, 6 dollar amounts and 5 percentages. Each field's label names exactly what to enter, and the prefilled value shows what a typical entry looks like.
Which energy & utilities calculators show a period-by-period schedule?
None of the 8 energy & utilities calculators builds a schedule: each returns its result directly from the formula, so the worked example and the sensitivity tables are the evidence to read.
What does the electricity cost calculator show at its worked example?
At the worked-example inputs the cost for the period is $61. It rises with hours used per day, electricity price per kwh, power draw (watts) and days of use. Across every input tested, hours used per day moves it most.