About OrcaCalc

OrcaCalc is a free library of calculators for everyday decisions: how much gravel a driveway needs, what a test score works out to, or what your weighted GPA really is. We currently publish 32 calculators and add new ones every week.

What makes our calculators different

• We show our work. Every page states the exact formula, walks through a worked example and lists the assumptions it makes.
• We cite primary sources. Unit conversions follow NIST; materials guidance links to manufacturers, extension services and industry bodies; grading guidance links to the College Board and the U.S. Department of Education.
• We test every formula. Each calculator has automated tests that check its results against hand-worked examples before it is published.
• Fast and private. Calculations run in your browser. We do not store what you type.

Who we are

OrcaCalc is an independent site. Our editorial team writes and reviews each calculator under our editorial policy.

Contact

Found a mistake or want a calculator we don't have? Tell us — corrections are reviewed within a few business days.

Advertising

OrcaCalc is supported by ads, including Google AdSense. Advertisers have no influence over our calculators or content. See our privacy policy for how ads use cookies.