Rule of three calculator

corresponds to B × Value C ÷ Value A. The rule of three assumes direct proportionality: doubling the starting quantity doubles the output. Fixed charges or bulk discounts break this assumption.

The rule of three assumes direct proportionality: doubling the starting quantity doubles the output. Fixed charges or bulk discounts break this assumption. The formula uses the specified units. Displayed numbers are rounded; whole packs, item counts and full time periods may also be rounded within the calculation.

The formula uses the specified units. Displayed numbers are rounded; whole packs, item counts and full time periods may also be rounded within the calculation. Prices, measurements and model assumptions determine how well the result represents your situation.

Yes. Calculations and PDF export work without an account or registration.

Calculations run in your browser. Results are saved locally only when you add them to My results; favourites and history are also local. Shared links contain your values. The currency tool requests the selected currencies from its rate provider without sending your amount.