This is a complete set of 15 free, browser-based calculators for the everyday math people run into constantly - working out a discount, splitting a bill, checking a grade point average, converting a number base, or finding how many days are left until an event. Every calculator here runs instantly and entirely on your own device.

There's no software to install, no account to create, and no limit on how many times you can use any tool. Open the calculator you need, enter your numbers, and get your answer immediately.

Why use a dedicated calculator instead of a general search?

A quick web search can sometimes give a rough answer to a simple calculation, but it won't walk you through a discount plus tax, a GPA weighted by credit hours, or a proportion with a missing value - and it definitely won't let you adjust your numbers and instantly see a new result. These calculators are purpose-built for their specific job, with the right inputs, the right formula, and a clear, instant answer every time - plus a full explanation of the math underneath, in case you want to understand how the answer was reached.

What each calculator does

Percentage Calculator - find X% of Y, what percent one number is of another, or a percentage increase/decrease
Date Calculator - find the days between two dates, or add/subtract days from a date
Age Calculator - find your exact age in years, months, and days, plus your next birthday countdown
Time Calculator - add or subtract hours, minutes, and seconds
Discount Calculator - find the sale price and savings for any discount percentage
Tip Calculator - calculate a tip and split the bill among any number of people
GPA / Grade Calculator - calculate a weighted grade point average from course grades and credit hours
Average / Mean Calculator - find the mean, median, mode, sum, and range of a list of numbers
Ratio & Proportion Calculator - simplify a ratio or solve a proportion for a missing value
Scientific Calculator - trigonometry, logarithms, powers, roots, and memory functions
Day Counter / Countdown - count the days until a future date, or since a past one
Day of the Week Calculator - find what day of the week any date falls on
Roman Numerals Converter - convert between numbers and Roman numerals
Binary / Hex / Decimal Converter - convert instantly between binary, decimal, hex, and octal
Random Number Generator - generate one or many random numbers within a chosen range

How to choose the right calculator

If your question involves dates and time - how long until an event, what day something falls on, how old you are, or a duration in hours and minutes - reach for the Date, Age, Time, Day Counter, or Day of the Week calculators. If it's about money or percentages, the Percentage, Discount, or Tip calculators cover the most common everyday cases. For school and grading, the GPA/Grade Calculator handles weighted averages. For a set of numbers you want to summarize or compare, the Average/Mean and Ratio & Proportion calculators are built for exactly that. And for anything technical - number base conversion, trigonometry, or generating random values - the Scientific Calculator, Binary/Hex/Decimal Converter, and Random Number Generator are purpose-built for those tasks.

Is it really free?

Yes - every calculator on this page is completely free, with no usage limits and no account required. Since all the math happens on your own device rather than a paid server, there's no per-calculation cost to offset.

Frequently asked questions

Do I need to install anything?

No - every calculator runs directly in your web browser. There's nothing to download or install beyond the page itself.

Is my data stored or sent anywhere?

No. All calculations happen locally in your browser using JavaScript. Nothing you enter is transmitted to a server or saved anywhere.

Can I use these calculators on my phone?

Yes - every calculator is fully responsive and works on any modern phone, tablet, or desktop browser.

Are the results accurate enough for schoolwork or financial decisions?

Yes - each calculator uses the standard, correct formula for its calculation. That said, for high-stakes financial or academic decisions, it's always a good idea to double-check important figures against your institution's or employer's official records.