What does the Dice Probability Calculator work out?

Exact odds of rolling a total on any number of dice. It is one of the Randomizers & Pickers tools on Mondo Knows.

How is the Dice Probability Calculator calculated?

Work out the chance of hitting a target before you commit to the roll. The counts are exact, not simulated: every combination of faces is enumerated, so a d6 question and a d20 question are equally precise. The maths is short enough to check by hand: Count the ways each total can be rolled by convolving the face counts once per die, then divide by sides^dice. 'At least' sums the counts at or above the target.

Do I need to sign up, and is my data stored?

No sign-up, and nothing you type is sent anywhere. The calculation runs in your own browser, so the figures stay on your device and the page works offline once loaded.

Mondo Knows Tools

Dice Probability Calculator

Exact odds of rolling a total on any number of dice. Use the free dice probability calculator below to get an instant answer, with the formula shown so you can check the maths and trust the result. Free, private, and no sign-up.

Number of dice

Sides per die

Target total

Chance of rolling

Mondo says

Fill in the fields, then press Work out the odds.

How it works

Work out the chance of hitting a target before you commit to the roll. The counts are exact, not simulated: every combination of faces is enumerated, so a d6 question and a d20 question are equally precise.

The formula

Count the ways each total can be rolled by convolving the face counts once per die, then divide by sides^dice. 'At least' sums the counts at or above the target.

Dice Probability Calculator: common questions

What does the Dice Probability Calculator work out?: Exact odds of rolling a total on any number of dice. It is one of the Randomizers & Pickers tools on Mondo Knows.
How is the Dice Probability Calculator calculated?: Work out the chance of hitting a target before you commit to the roll. The counts are exact, not simulated: every combination of faces is enumerated, so a d6 question and a d20 question are equally precise. The maths is short enough to check by hand: Count the ways each total can be rolled by convolving the face counts once per die, then divide by sides^dice. 'At least' sums the counts at or above the target.
Do I need to sign up, and is my data stored?: No sign-up, and nothing you type is sent anywhere. The calculation runs in your own browser, so the figures stay on your device and the page works offline once loaded.

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Estimates for general guidance only. This is not financial, medical or legal advice. Everything runs in your browser and nothing you type is stored.