Best Online Calculators for Everyday Use

From splitting a bill to checking a loan offer, these free calculators answer the number questions that come up every week.

Most of the maths we do in daily life is the same handful of questions asked again and again. What is 15% of this? How much will I really pay each month? How old will I be on that date? A good calculator answers in seconds — and shows enough of the working that you can trust the result.

Here are the calculators we see people reach for most, and when each one helps.

Percentages without the mental gymnastics

The Percentage Calculator covers the four questions that cause most confusion: X% of Y, X is what percent of Y, the percentage change between two numbers, and increasing or decreasing a value by a percentage. That last one matters more than it looks: a 20% increase followed by a 20% decrease does not bring you back to where you started.

Shopping and eating out

• The Discount Calculator handles stacked discounts ("extra 10% off sale prices") and adds tax so you see the real checkout price.
• The Tip Calculator splits a bill between friends and can round each share up to a tidy amount.

Borrowing money

Before you sign a loan agreement, run the numbers yourself. The Loan EMI Calculator shows the monthly instalment, the total interest and how much of each year's payments goes to interest versus principal. If you want to see every payment, the Loan Amortization Calculator builds the full schedule — and shows how much an extra monthly payment would save.

Results are estimates. Lenders may add fees or use slightly different rounding, so always compare with the official offer.

Dates and ages

Forms that ask for an exact age, or deadlines counted in business days, are easy to get wrong by hand. The Age Calculator gives years, months and days (and handles 29 February birthdays), while the Date Calculator counts days between dates or adds days, weeks and months.

Students

The GPA Calculator supports both the US 4.0 scale and the Bangladesh UGC scale, and can combine a new semester with your previous CGPA. The Scientific Calculator handles trigonometry, logarithms and powers with full keyboard support.

A quick tip

Whatever you calculate, write down the inputs you used. When a result surprises you, the cause is almost always an input — a monthly rate typed as yearly, or a total that should have been per person. Browse the full calculator category to find the one you need.