Yes. Every calculator is free to use with no account and no sign-up. The site may show advertising to cover its costs.
From primary sources: manufacturer technical data sheets for bag yields and coverage rates, current retailer listings and supplier price sheets for prices, the U.S. Energy Information Administration for electricity prices, and NREL for solar data. Each calculator lists its sources and the date we last checked them.
Usually because of waste and rounding. We add a sensible overage (which you can change) and round up to whole packages. Some calculators also use older yields — for example, assuming a bag makes 0.5 cubic feet. We use the current published figure and show it next to the result.
Yes. Tap any price in a cost estimate and type your local price. The calculator remembers it in your browser for next time.
Click “Save to project” under any calculation. Projects are stored only in this browser — nothing is uploaded — and each project combines its calculations into one shopping list you can print or copy.
Yes. Use the ft · in / m · cm switch on any calculator. You can also type values like 3.2m or 10'6" directly into length fields.
No. They are planning estimates. Site conditions, product batches and local codes vary, so confirm critical quantities with your supplier and structural or code questions with a licensed professional.
Use the contact form or email contact@gablemath.com. Data corrections are reviewed first.
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