Ratio Calculator

A ratio simplifies by dividing both sides by their greatest common divisor, so 16 : 9 stays as it is while 1920 : 1080 becomes 16 : 9. A proportion is A : B = C : D, which cross-multiplies to A x D = B x C. Solving for the missing one gives D = B x C / A.

How do I split something in a ratio?

Add the parts, then give each side its share. Splitting 500 in the ratio 3 : 2 means 5 parts of 100, so 300 and 200. The percentage line above does this for you.

What is a proportion?

Two ratios that are equal. If 3 apples cost 2 dollars, then 12 apples cost 8, because 3 : 2 = 12 : 8. Cross-multiplying finds the missing number in any of the four spots.

What does 16 : 9 mean for a screen?

For every 16 units of width there are 9 of height. A 1920 pixel wide screen at 16 : 9 is 1080 tall, which is exactly what this page returns if you enter 16, 9, 1920 and leave D at zero.

Is a ratio the same as a fraction?

Nearly. 3 : 4 as a fraction of the whole is 3/7, not 3/4, because the ratio compares the two parts to each other while the fraction compares one part to the total. Mixing these up is the most common ratio mistake.