All Math Tools
Fraction Calculator
Add, subtract, multiply or divide fractions, simplified automatically.
OpenRatio Calculator
Simplify a ratio, or scale it to find a missing value.
OpenAverage Calculator
Mean, median, mode and range from any list of numbers.
OpenStandard Deviation Calculator
Population and sample standard deviation, with variance and mean.
OpenTip Calculator
Tip amount and per-person split for any bill.
OpenGPA Calculator
Weighted GPA from your course grades and credit hours.
OpenBill Splitter
Split a restaurant bill fairly when everyone didn't order the same amount.
OpenRandom Number Generator
Pick random numbers in a range, with or without repeats.
OpenRandom Team & Name Picker
Paste a list of names, split into random teams or pick random winners.
OpenTrip Expense Splitter
Track group expenses on a trip and see exactly who owes whom, simplified.
OpenAbout these tools
Six calculators for the arithmetic that comes up constantly but is easy to get wrong by hand — simplifying a fraction, scaling a ratio, or working out whether a data set is tightly clustered or spread out. Each one shows its working, not just the answer.
Nothing here needs an account, and nothing you put into any of them is uploaded or stored. Every tool is a single page that does one job, so you can bookmark the one you use and skip this page entirely next time.