15 free calculators, no sign-up
Free online calculators. Answers with the working shown.
Time cards, concrete, tips, sales tax, grades, zakat and more. Instant results on any device, with every step of the calculation laid out so you can check it.
- Free to use
- No account needed
- Runs in your browser
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Popular calculators
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Time & Date
Hours Calculator
Add up the hours worked from start and end times, minus breaks, for a daily or weekly time card.
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Time & Date
Days Between Dates Calculator
Count the days, weeks and months between two dates, or count weekdays only.
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Time & Date
Date Calculator
Add or subtract days, weeks, months or years from a date, count business days, or find the weekday.
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Home & DIY
Concrete Calculator
Cubic yards, cubic meters and bags of concrete for slabs, footings, columns, stairs and post holes.
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Home & DIY
Square Footage Calculator
Total area of rooms of any shape in square feet, square meters and square yards, with waste and cost.
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Money
Tip Calculator
Work out the tip and total for any bill, then split it evenly between any number of people.
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Money
Sales Tax Calculator
Add sales tax to a price, take it out of a total, or find the rate, for all 50 states plus local rates.
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Islamic
Zakat Calculator
Calculate the zakat due on your savings, gold, silver and investments at 2.5%, using the gold or silver nisab.
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About these calculators
Every calculator here runs in your browser. The numbers you type stay on your device, and nothing needs an account.
Each page explains the formula in plain English, works through an example with real numbers, and answers the questions people most often ask about it. Where a result depends on a method or a local rule, such as the nisab standard for zakat, moon sighting for Hijri dates, or city and county sales tax, the page says so.