WHAT THIS TOOL DOES

This odds to probability calculator converts odds written as a:b into probability.

It works for odds for and odds against, then shows the answer as a simplified fraction, decimal and percentage.

Best folder name: odds-to-probability

HOW TO USE IT

Choose whether the odds are odds for or odds against.

Enter the two values in the odds ratio a:b.

Choose rounding for the decimal and percentage output.

Press SOLVE to see the working, simplified fraction, decimal and percentage.

FORMULAS

Odds for a:b means a favourable parts and b unfavourable parts.

Probability = a ÷ (a+b).

Odds against a:b means a against parts and b favourable parts.

Probability = b ÷ (a+b).

EXAMPLES

Odds for 3:2 gives probability 3 ÷ (3+2) = 3/5 = 60%.

Odds against 3:2 gives probability 2 ÷ (3+2) = 2/5 = 40%.

Odds for 1:4 gives probability 1 ÷ 5 = 20%.

The words “for” and “against” change which side is favourable.

WHO USES IT

Students use it for probability, odds questions, games of chance and exam revision.

Teachers and tutors use it to show the difference between odds for, odds against and probability.

Anyone comparing chance statements can use it to convert odds into a percentage.

Common searches: odds to probability calculator, convert odds to percent, odds against probability.

DEVICE HELP

The calculator is split into input and result pages so mobile screens do not crush the buttons or hide the answer.

Extra SEO help pages are split here to avoid hidden text behind the Teletext footer.

Inputs and buttons include accessible labels. Keyboard: Enter solves. Escape resets to the worked example.

Every internal page keeps PREV and NEXT visible.

RELATED PAGES

This page follows combined probability and links onward to probability to odds.

Use the probability hub for dice, coins, random numbers, expected value and risk tools.

Internal NEXT loops back to the calculator page.