Math calculators

Percentages and averages worked out instantly, with the formula and an example on every page.

All tools in this category

• Percentage Error CalculatorCalculate percentage error from measured and reference values. See signed error, absolute error and the formula, including negative reference values.
• Standard Deviation CalculatorCalculate sample or population standard deviation, variance, mean and count. Paste a numeric list, compare formulas and see worked examples in your browser.
• Ratio CalculatorSimplify a two-part ratio, solve a missing proportion or divide a total into shares. See the common factor and each part’s percentage in your browser.
• Running Pace CalculatorCalculate pace, finish time or distance in kilometres and miles. Compare pace per km and mile, speed and cumulative steady-pace splits in your browser.
• GPA CalculatorCalculate your semester GPA and cumulative CGPA from course grades and credit hours, on 5-point (KSU), Pakistan HEC 4.0 or US 4.0 scales. Free.
• CGPA to Percentage ConverterConvert CGPA to percentage with Pakistan's official HEC table (3.00 = 71%, not 75%), and see common formulas for 10, 4 and 5-point scales. Free.
• Percentage CalculatorWork out a percentage of a number, what percent one number is of another, or the whole from a part. Free, instant and private, right in your browser.
• Percentage Change CalculatorFind the percentage increase or decrease between two numbers, or add or subtract a percentage from a value. Free and instant, right in your browser.
• Average CalculatorFind the average (mean), median, mode, sum and range of a list of numbers. Paste a column from a spreadsheet; it's free, instant and private.
• Roman Numerals ConverterConvert numbers to Roman numerals and back (1 to 3,999), turn a date into Roman numerals for a tattoo or engraving, and see a 1–100 chart.
• Land Area ConverterConvert marla, kanal, bigha, katha, decimal, gaj, acre, hectare and square feet, with both Pakistani marla sizes and the bigha of each region.
• Random Number GeneratorPick one or many random numbers between any two whole numbers, with or without repeats. Truly random, from your device's secure generator.
• Fraction CalculatorAdd, subtract, multiply and divide fractions and mixed numbers, with the answer simplified, as a mixed number and as a decimal. Free.
• Grade CalculatorFind the score you need on your final exam to reach your target grade, or work out your current weighted grade from your marks so far.