Math Calculators

Choosing the right math calculator

Percentages. Use the percentage calculator when you have one number and want a share of it. Use the percentage change calculator when you are comparing an old value with a new one, such as a price rise or a drop in sales.

Fractions and ratios. A fraction compares part of something to the whole: 3/4 of a pizza. A ratio compares two quantities with each other: 3 parts flour to 1 part sugar. The fraction calculator adds, subtracts, multiplies and divides fractions exactly. The ratio calculator simplifies ratios and fills in the missing term of a proportion.

Statistics. The average calculator gives the mean, median and mode of a list together. Looking at all three is often more informative than the mean alone, especially when the data contains outliers.

If you’re not sure which tool fits, start from the question you’re asking:

Math concepts covered

Percentages

The percentage calculator answers the three everyday percentage questions: a percentage of a number, what percent one number is of another, and the original whole when you only know a part. It’s the tool for discounts, tips, sales tax, test scores and commission. The percentage change calculator measures movement between two values, such as a price going from $80 to $100 (a 25% increase), and also shows the symmetric percentage difference for comparisons with no clear starting point.

Fractions and ratios

The fraction calculator does exact arithmetic on two fractions and gives the answer in lowest terms, as a mixed number and as a decimal. It’s useful for homework, recipes and inch measurements. The ratio calculator solves proportions like 4 : 250 = 6 : ? and reduces ratios such as 1920 : 1080 to 16 : 9, which covers recipe scaling, map scales, mixing instructions and screen aspect ratios.

Statistics

The average calculator takes a pasted list of up to 10,000 numbers and returns the mean, median, mode, count, sum, range, minimum and maximum. Seeing the mean and median side by side shows at a glance whether a few extreme values are skewing the result.

Step-by-step math guides

• How to calculate percentage change covers the formula, percentage points versus percentage change, negative starting values and why successive changes multiply.
• Fractions, decimals and percentages shows how to convert between the three forms, with a conversion table and the repeating decimals to watch for.
• Mean, median and mode explained explains when each average is the right one, and how outliers and skew affect them.

Glossary

• Percentage: a number expressed as a part of 100. 45% means 45 per 100, or 0.45.
• Percentage point: the simple difference between two percentages. A rate rising from 3% to 5% went up 2 percentage points, which is a 66.67% increase in the rate.
• Fraction: a part of a whole written as numerator over denominator, such as 3/8.
• Ratio: a comparison of two quantities, such as 3 : 2. It describes how the parts relate to each other rather than to the total.
• Proportion: a statement that two ratios are equal, such as 3 : 2 = 9 : 6. Solving one finds a missing term.
• Mean: the sum of the values divided by how many there are. This is what most people mean by “average”.
• Median: the middle value of a sorted list, or the average of the two middle values when the count is even.
• Mode: the value that appears most often. A list can have one mode, several, or none.

Money calculations such as interest, loans and returns are in the finance calculators, and date and time arithmetic is in the time and date calculators.