A clearer view
of the numbers.

Choose the calculation that matches the question

Percentage Calculator supports several operations, including finding a percentage of a value and increasing or decreasing a value by a percentage. Read the labels carefully: “A percent of B” and “A as a percentage of B” answer different questions.

Number Base Converter translates integers between supported bases such as binary, decimal, octal, and hexadecimal. Statistics Calculator summarizes a list using measures such as mean, median, mode, and population standard deviation.

Make assumptions explicit

A percentage change needs a starting value. A zero starting value makes the usual percentage-change calculation undefined. For statistics, a mean can be pulled by an unusually large or small observation, so review the dataset and compare the mean with the median.

Population standard deviation treats the entered values as the complete population. If the values are a sample and your analysis requires a sample estimate, use the appropriate calculation instead. A summary does not establish whether the sample is representative or whether a difference is meaningful.

Check inputs before trusting outputs

1. Remove units or labels from a numeric list only when you know all values share the same unit.
2. Keep missing observations separate from zero values.
3. Check supported integer ranges before converting large identifiers between bases.
4. Review rounding and use an independent calculation for consequential decisions.

These tools are intended for quick arithmetic and exploration. They do not replace a documented analysis process. For dates and time intervals, use Date & time tools; for a reproducible error, send feedback.