Free tools
Free, no sign up, and the maths runs in your browser so nothing you type is sent anywhere. Each one shows its working, because a number you cannot check is not much use when you are spending four figures.
Put in the quote you were actually given. The tool does the arithmetic the trade uses, and shows its working.
Open the calculator →Square footage is the starting point, not the answer. Sun, insulation, ceiling height and climate move the number a long way.
Open the calculator →Both federal credits expired at the end of 2025. Most articles on this topic have not been updated. Here is what is genuinely still available.
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