Calculators.
Clear answers to everyday number questions.
Percentage Calculator
Calculate a percentage of a number, percentage increase or decrease, and one number as a percentage of another.
Age Calculator
Work out age in years, months and days from a date of birth — today, or as on any date a form asks for.
Discount Calculator
Calculate the sale price after a percentage discount and see exactly how much you save.
Date Difference Calculator
Calculate days between two dates and compare the interval in calendar years, months, weeks and days.
Tip Calculator
Calculate a tip and split the total bill evenly.
Average & Median Calculator
Find the mean, median, range endpoints, and count of a number list.
Ratio Calculator
Simplify a ratio to its lowest terms, or solve a proportion for the missing value.
GPA Calculator
Calculate a weighted GPA on the standard 4.0 scale.
Quadratic Equation Solver
Solve ax² + bx + c = 0 for real or complex roots.
Work Hours Calculator
Add up hours worked across shifts, minus breaks.
Business Days Calculator
Count the working days between two dates, excluding weekends and any holidays you list.
Countdown Timer
Calculate the days, hours, minutes and seconds between two exact dates and times.
About calculators
Everyday arithmetic that is easy to get subtly wrong: what percentage one number is of another, how many days sit between two dates, how a bill splits with a tip, the average and median of a set, a ratio reduced to its simplest form, a GPA across courses with different credit weights.
Each tool shows the formula it used alongside the answer, so you can check the method rather than trusting the output. Several also handle the cases where the edges matter — business days that skip weekends, work hours across a break, dates spanning a leap year.