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Everyday calculators & converters

The quick calculations that come up every day. Work out a percentage, a discount or a fraction, calculate your age or the days between two dates, and add up hours worked for a timesheet.

Students can calculate GPA, test grades and the score needed on a final exam. Around the house there are paint, square footage, roof pitch and fuel cost calculators. There are also converters for length, weight, temperature, cooking measurements, time zones, military time and Roman numerals, plus timers, a countdown clock and a random number generator.

All 30 tools

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Percentage Calculator

Percent of a number, ratio & percent change.

½

Fraction Calculator

Add, subtract, multiply & divide fractions.

🏷️

Discount Calculator

Sale price, savings & final total with tax.

🎂

Age Calculator

Exact age, total days lived & next-birthday countdown.

📅

Days Between Dates

Days, weeks & months between any two dates.

⏱️

Time Calculator

Add/subtract hours & minutes, total timesheet lists.

⏱️

Hours Calculator

Time between two times, minus breaks — for timesheets.

⏱️

Timesheet Calculator

Weekly time card with breaks, OT & pay.

🎓

GPA Calculator

Weighted GPA on a 4.0 scale from your courses & credits.

🎓

Final Grade Calculator

What score you need on the final to hit your target grade.

✏️

Test Grade Calculator

EZ-grader: wrong answers → score + chart.

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Weighted Grade Calculator

Categories × weights → your real class grade.

😴

Sleep Calculator

Best bedtimes & wake-up times by 90-minute cycles.

🚗

Speed · Distance · Time

Enter any two, get the third.

🏃

Running Pace Calculator

Pace per mile & km from distance + time.

Fuel Cost Calculator

Estimate gas cost for any trip.

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Square Footage Calculator

Area in ft² for rooms & flooring.

🎨

Paint Calculator

How many gallons your walls need.

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Roof Pitch Calculator

Rise/run → pitch, angle & slope.

🖼️

Aspect Ratio Calculator

Resize dimensions keeping the ratio.

🥄

Cooking Measurement Converter

Cups, tbsp, tsp, fl oz & mL — convert instantly.

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Temperature Converter

Celsius, Fahrenheit & Kelvin at once.

📏

Length Converter

Feet, meters, inches, miles & more.

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Weight Converter

Kg, lb, oz, grams & stone.

🌐

Time Zone Converter

Meeting times across world zones, DST handled.

🪖

Military Time Converter

24-hour ⇄ AM/PM + the full chart.

Roman Numeral Converter

Numbers ⇄ Roman numerals, both ways.

Countdown Timer

Live countdown to any date — Christmas, New Year & more.

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Online Timer & Stopwatch

Countdown with alarm, plus a stopwatch.

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Random Number Generator

Pick numbers in any range, with or without repeats.

Frequently asked questions

How do I calculate a percentage of a number?

Multiply the number by the percentage and divide by 100. For example, 15% of 80 is 80 x 15 / 100 = 12. The percentage calculator also handles percentage change and 'X is what percent of Y'.

What score do I need on my final exam?

Enter your current grade, the grade you want, and how much the final is worth. The final grade calculator tells you the score you need.

How much paint do I need?

A gallon typically covers about 350-400 square feet per coat. Enter your total wall length, wall height and number of coats, and the paint calculator tells you how many gallons to buy.

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