OpenCalculator, also written Open Calculator, is the calculator website at opencalculator.app. It brings 35 calculators together across 10 topics, from percentages and fractions to paychecks, school grades, dates, and calculus. You can start calculating without an account or an installation.
A result, with a way to check it
A useful answer needs context. Calculator pages include formulas, worked examples, assumptions, and related tools. The percentage calculator explains the difference between percent of a number and percent change. The compound interest calculator separates contributions from interest. The GPA calculator shows how grades and credits combine.
Use a quick answer or a full calculator
The homepage calculators work directly on the page. Open a calculator for more options and its explanation. To solve for a different unknown, try equations with a movable blank: for example, start with a target take-home pay and solve for the salary.
Keep the calculation
A calculation can be shared as a link that restores its inputs. The full calculator pages also offer answer images, PDF downloads, and Excel exports. Supported spreadsheets contain live formulas; other exports preserve the inputs, result, and steps as values. Pick several homepage calculators to share them together on one page.
Understand the limits
School grading policies, payroll deductions, taxes, benefit eligibility, and exam scoring can differ from a calculator's assumptions. Health tools provide arithmetic or statistical estimates and cannot choose a treatment or diagnose a condition. Read the methods and sources and each page's notes before using a result for a decision.
OpenCalculator is not affiliated with the IRS, Social Security Administration, Department of Veterans Affairs, College Board, or ACT. Official records and the relevant organization's rules take precedence over estimates here.