Math & Dates
Everyday math and calendar helpers in one place. Work out percentages and averages, calculate exact age in years, months and days, count the days between two dates (including business days), work out your term and cumulative GPA or watch a live countdown to your next big event. All calculations happen in your browser.
6 free tools. Tap any card to open it. No sign-up needed.
Percentage CalculatorSolve the four most common percentage problems instantly.Average CalculatorGet mean, median, mode, range and standard deviation for any list of numbers.Age CalculatorFind your exact age and how many days remain until your next birthday.Date Difference CalculatorCount the days, weeks, months and business days between any two dates.Countdown Timer to a DateCount down the days, hours, minutes and seconds to any event.GPA Calculator NewWork out your term and cumulative GPA and what you need to reach a target.
Quick guide to these calculators
- Percentages: the percentage calculator answers "what is X% of Y", "X is what percent of Y" and percentage change. See how to calculate percentage increase.
- Averages: the average calculator gives the mean, median and mode of a list in one go.
- Age and dates: the age calculator gives exact age in years, months and days, and the date difference calculator counts days and business days between two dates.
- Events: the countdown timer shows a live count to any date.
Avoid the common mistakes
Percentage change is always divided by the starting value. When counting days, decide first whether you include both the start and the end date. Business-day counts skip weekends, but public holidays differ by country, so check your local calendar for deadlines that matter. Our math and date guides work through each case with examples.
Guides and articles
- How to Calculate EMI: Formula, Example and TipsLearn the EMI formula for home, car and personal loans, work through a full example by hand, and see how rate and tenure change your monthly payment.
- How to Calculate Sales Tax (and Remove It From a Total)Learn how to add sales tax, GST or VAT to a price, how to work backwards to the pre-tax amount, and the mistakes that give wrong answers.
- How to Convert an Hourly Wage to a Yearly SalaryTurn hourly pay into yearly, monthly and weekly salary (and back), with the 2,080-hour rule, quick mental shortcuts and the details that change the result.
- Profit Margin vs Markup: What’s the Difference?Margin and markup use the same numbers but answer different questions. Learn both formulas, convert between them and price products correctly.
- How to Calculate Percentage Increase and DecreaseThe percentage increase formula explained simply, with examples for prices, pay and grades, plus percentage decrease, reverse percentages and common traps.
- How to Calculate Age From Date of Birth (Years, Months, Days)Calculate exact age in years, months and days from a date of birth, by hand, in Excel or Google Sheets, with clear rules for leap years and month ends.
