This is a simple calculator that helps you understand what drop chance in Warframe actually means. Use the form below to calculate the chance of getting an item once in multiple runs.

The drop chance for each run stays always the same. But each repeated run with the same drop chance increases your chance of being successful. The calulation is done by using the fail chance and put it to the power of runs.

A 10% drop chance item has a 90% probability (0.9) to not drop. For ten runs this means 0.9^{10} to not drop. This results in 0.35, meaning 35% chance of not succeeding in 10 runs. And this again means 65% chance of succeeding (at least once) in 10 runs.

A 10% drop chance item has a 90% probability (0.9) to not drop. For ten runs this means 0.9

The calculation of the number of runs it takes you to have 90 or 99 percent chance of succeeding (getting a drop) is a bit more complex because it involves logarithmic calculations.

The probability of something not droping is used a logarithmic base and one minus the percent chance you want to calculate is used in the operator.

To calcate the number of runs needed to achieve a 95% chance to succeed at least one for an item with 10% drop chance that results in log_{0.9}(1-0.95) = 28.43 runs.

The probability of something not droping is used a logarithmic base and one minus the percent chance you want to calculate is used in the operator.

To calcate the number of runs needed to achieve a 95% chance to succeed at least one for an item with 10% drop chance that results in log

The simple odds calculator is not perfect. It provides a simplified view of drop chance. If you want to nerd out on the subject here are some additional resources: