Know your number before it counts.
Ten precise, free calculators. Find your class grade, the score you need on a final, your GPA or the days between two dates, then check the chance of a snow day, measure a room, solve a ratio or split a tip.
All calculators
Snow Day Calculator
Check the live forecast for your ZIP code and see the chance school is closed or delayed tomorrow.
Open calculator →Square Footage Calculator
Measure rooms, yards and odd shapes in square feet, with waste allowance and project cost.
Open calculator →Ratio Calculator
Solve proportions like 3:4 = x:20, simplify any ratio and see it as a fraction and percentage.
Open calculator →Tip Calculator
Work out the tip, the total and each person's share when you split the bill, with rounding.
Open calculator →Answers as you type
Every result updates instantly. There's no calculate button and no page reload.
Private by design
Your grades and dates stay on your device. Nothing you type is stored.
Formulas shown
Each tool explains its formula with a worked example, so you can check the math yourself.
Made for phones
Large inputs and clear results work as well on a phone as on a laptop.
Questions
Are these calculators free?
Yes. Every calculator is free to use with no sign-up and no limits.
Is my data saved or sent anywhere?
No. Calculations run in your browser and nothing you type is stored. The one exception is the snow day calculator, which sends the ZIP code or town you enter to a weather service to get the forecast.
Which grading scale do you use?
The standard U.S. scale: 90–100 is an A, 80–89 a B, 70–79 a C, 60–69 a D and below 60 an F, with plus and minus cutoffs. Each tool explains its scale in detail.
Do the tools work on my phone?
Yes. Every calculator is built for phones, tablets and desktops, with large inputs and results that update as you type.