Energy and Sustainability Calculators
These calculators answer the money and carbon questions that come up when a household thinks about electrifying: what our footprint actually is, whether an electric car will pay for itself, how long it takes to charge, whether a heat pump beats the furnace we have, and how many years rooftop solar needs to pay back. Each one starts from numbers on your own bills and quotes, shows a result straight away and lists the formula and factors it used.
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All Energy & Sustainability (5)
Carbon Footprint Calculator
Household CO₂e from energy, driving, flights and dietEV vs Gas Cost Calculator
Running cost, CO₂ and break-even of an EV versus a petrol carEV Charging Time & Cost Calculator
Charge time and cost by charger power, battery and tariffHeat Pump Savings Calculator
Running cost of a heat pump versus gas, oil or resistance heatSolar Payback Calculator
Payback years, savings and ROI of solar panels after incentives
Which tool do I need?
Work out my household carbon footprint
Turn a year of electricity, gas, driving, flights and diet into tonnes of CO₂e and see which source is largest.
Decide between an electric car and a gas car
Compare yearly fuel, charging and maintenance costs, the break-even on a higher EV price and the CO₂ difference on your grid.
Find out how long my EV takes to charge and what it costs
Enter the battery, start and target charge and the charger to get time, cost and range added on Level 1, Level 2 or DC.
Check whether a heat pump would save money
Compare a heat pump with your gas, oil, propane or baseboard heating from your fuel bills, with payback and break-even prices.
See how many years solar panels take to pay back
Model payback, ROI, NPV and cost per kWh with export rates, degradation, rising prices and inverter replacement.
About Energy & Sustainability
Defaults come from primary sources and are always editable. Emission factors are from the US EPA GHG Emission Factors Hub 2025, including eGRID2023 rates for all 26 US grid subregions, and from the UK government's DESNZ 2025 conversion factors for flights and UK electricity. Energy prices are the US Energy Information Administration's October 2026 forecasts, and fuel heat contents are the EIA's published values. Federal incentives that ended in 2025, such as the 25C, 25D and 30D credits, default to zero.
Everything runs in your browser, so the figures you enter stay on your device. The results are estimates: a heat pump's real seasonal efficiency, a car's real charging curve and future energy prices all vary, so each calculator shows how sensitive its answer is to the assumption that matters most.
Guides
- How to Calculate Your Carbon Footprint from Your BillsTurn kWh, therms, gallons, miles and flights into tonnes of CO2e with EPA 2025 and DESNZ 2025 factors, and see which part of a household footprint is biggest.
- EV vs Gas: Running Cost, Break-Even and CO2 ComparedCost per mile for electric and gasoline cars, how home versus public charging changes the answer, how long a higher EV price takes to pay back, and grid CO2 by region.
- Heat Pump vs Gas Furnace: Running Costs and PaybackCost per kWh of heat for gas, oil, propane and heat pumps, the break-even electricity price, what COP and HSPF2 mean, and why backup heat matters.
- Solar Panel Payback Period: How to Work It Out HonestlyPayback, ROI, NPV and cost per kWh for rooftop solar, with export rates, degradation, inverter replacement and the end of the US 25D credit in the numbers.
Frequently asked questions
Where do the emission factors in these calculators come from?
Fuel and US electricity factors are from the EPA GHG Emission Factors Hub 2025, which uses eGRID2023 grid data and IPCC AR5 warming potentials. Flight and UK electricity factors are from the UK DESNZ 2025 conversion factors. Each calculator shows the factor it applied.
Are the energy prices current?
Defaults use the EIA Short-Term Energy Outlook of October 2026: about 18 cents per kWh for US residential electricity and $3.90 a gallon for gasoline in 2026, with winter heating fuel prices for 2026-27. Replace them with the prices on your own bills for a personal answer.
Do these calculators include federal tax credits?
The federal credits for EVs (30D), home efficiency upgrades such as heat pumps (25C) and residential solar (25D) ended in 2025 under the One Big Beautiful Bill Act, so incentive fields default to zero. Enter any state, utility or local rebate you qualify for.
Which electrification step saves the most?
It depends on what you replace. Swapping oil, propane or electric baseboard heat for a heat pump, or a high-mileage gas car for an EV charged at home, usually saves the most money. Replacing an efficient gas furnace saves the least at current US prices. Run your own numbers in each calculator.
Do the CO₂ results include manufacturing emissions?
No. The calculators count emissions from using fuel and electricity, not from making cars, batteries, panels or heat pumps, or from producing the fuel. They show the operating difference between choices, which is the part your day-to-day decisions control.