Household Planning Calculators
Illustrative scenarios using your own inputs. Cost payback is separate from environmental impact. Equipment sizing tools are preliminary estimates; each calculator explains its assumptions and sources.
Run the numbers on your own home with your own utility rates. Calculations run in your browser. No signup is needed, and calculator inputs stay in this page. Free to use and link to.
Energy
Solar Panel Payback Calculator
Payback period, net cost after incentives, and 25-year cash scenario for a home solar system.
Off-Grid Solar Sizing Calculator
How many watts of panel, how much battery, and what size inverter for a van, RV or cabin.
Home Energy Savings Calculator
Annual savings from LED bulbs, a thermostat setback, and cutting standby power.
Heat Pump vs Furnace Calculator
Running cost against gas, propane, oil or electric heat, plus payback on the install premium.
Transport
Home & Garden
Rainwater Harvesting Calculator
Gallons your roof can collect, a dry-period storage scenario, and water-bill savings.
Reusable vs Disposable Payback
Whether a reusable swap pays for itself, and the disposables it avoids.
Low-Flow Water Savings Calculator
Gallons and dollars saved from a low-flow showerhead, aerators and an efficient toilet.
Compost Volume Mixing Planner
A practical starting mix by bucket volume, with moisture and aeration guidance.
Cloth vs Disposable Diaper Calculator
Estimated cost of cloth versus disposables including washing, and the break-even month.
Using these on your own site
Teachers, extension offices, sustainability programs and community groups are welcome to link to any of these calculators. They are free, contain no paywall or signup, and we keep the underlying assumptions documented on each page so you can check the math.
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