UsefulTab
Calculators
Quick everyday math — percentages, dates, health, and money.
15 tools in this category, all running locally in your browser.
Fast answers to the everyday numbers questions: percentages, discounts, tips, unit prices, loan payments, compound interest, fuel cost, BMI and calories, age and date differences, aspect ratios, and running pace. Type in your figures and the result appears immediately — no spreadsheets, no formulas to remember. Everything is calculated in your browser, so nothing you enter about your money, health, or plans is stored or sent anywhere.
Percentage Calculator
Calculate X% of Y, what percent one number is of another, and percent increase or decrease.
Discount Calculator
Work out the final price and savings from a single discount or several stacked discounts.
Tip Calculator
Enter a bill, tip percentage, and number of people to see the tip, total, and per-person share.
Unit Price Calculator
Enter the price and quantity of two products to see which is cheaper per unit.
Loan EMI Calculator
Work out the monthly EMI, total repayment, and total interest for any fixed-rate loan.
Compound Interest Calculator
Project a final balance and total interest earned from a principal, rate, term, and compounding frequency.
Fuel Cost Calculator
Enter trip distance, your vehicle's fuel economy, and the fuel price to see the fuel needed and total cost of the journey.
BMI Calculator
Calculate BMI from height and weight, with the World Health Organization category.
Calorie Calculator
Enter your age, sex, height, weight, and activity level to estimate your BMR and daily calorie needs using the Mifflin-St Jeor equation.
Age Calculator
Calculate exact age and total days lived from a date of birth.
Date Difference Calculator
Pick a start and end date to see the gap in days, weeks, months, and years.
Aspect Ratio Calculator
Enter an original width and height plus one new dimension, and get the matching dimension that preserves the aspect ratio.
Download Time Calculator
Enter a file size and your connection speed to see the transfer time and the exact clock time it finishes.
Pace Calculator
Find running pace, finish time, or distance from the other two values.
Random Wheel Picker
Enter names or options and spin a wheel to pick one at random.
Calculator guides
How to work out a percentage, a discount or sale price, the cheaper price per unit, and the number of days between two dates.
Calculate a percentage the easy way
The three percentage questions people actually ask — X% of Y, what percent is X of Y, and percent change — with the simple formula for each.
Compare price per unit between two products
A bigger pack isn't always cheaper. Work out the real price per unit of two products and see which one actually wins.
Calculate the difference between two dates
How many days until a deadline, or between two events? Pick a start and end date and see the gap in days, weeks, months and years.
Calculate a discount
Work out a sale price from a percentage off, do it in your head, stack discounts correctly, and check it instantly — all in your browser.
Common questions
Are these calculators free to use?
Yes. Every calculator is completely free, with no sign-up and no limit on how many times you use it.
Is my input private?
Yes. Calculations run in your browser. Financial figures, health numbers, and dates you type are never uploaded or saved on a server.
Are the results financial or medical advice?
No. These tools do the arithmetic for you but are for general information only. For decisions about money or health, consult a qualified professional.