Glossary

Plain-English definitions of the concepts behind our tools — each linked to the calculators that use it.

• Amortization

  Paying off a loan with equal periodic payments split between interest and principal.

• Arithmetic mean (average)

  The sum of a set of numbers divided by how many there are.

• Base64

  An encoding that represents binary data as ASCII text.

• Body mass index (BMI)

  A weight-to-height ratio used to screen for weight categories.

• Compound interest

  Interest earned on both the original principal and the interest already added.

• Factorial

  The product of all positive integers up to a given number (n!).

• Hexadecimal

  A base-16 number system using digits 0–9 and letters A–F.

• P-value

  The probability of data at least as extreme as observed, if the null hypothesis is true.

• Percentage

  A number expressed as a fraction of 100.

• Percentile

  The value below which a given percentage of the data falls.

• Standard deviation

  A measure of how spread out a set of numbers is around their mean.

• Value-added tax (VAT)

  A consumption tax collected at each stage of production, shown in the price.

• Variance

  The average of the squared differences from the mean.