Bū tools

Rule of three

A gives B, so C gives?

What it does

The rule of three: if A gives B, then C gives D. Type three numbers, D is computed as you type.

• Proportional: D = B × C ÷ A. 1920 px for 16 cm, so 1280 px for…?
• Inversely: D = A × B ÷ C. 4 people take 6 days, so 3 people take…?

Comma or point, any numbers. Tap the result to copy it.

Free, no account, nothing is sent: it runs in your browser, even offline.

Related tools

• QR code · A QR code with style
• Calculator · Simple or scientific, with history
• Hours calculator · Add up hours and breaks, in decimal hours and in money
• Ruler · A real-size grid to measure on the screen
• Coffee · Every coffee and its proportions
• Unit converter · Length, weight, temperature, data…
• Stage timer · A big countdown for a speaker, on a second screen
• Dice · Roll D4, D6, D8, D10, D12, D20

All tools · Français