🔢 Free Online Calculators — BMI, Loan, Age & Percentage
Free online calculators for everyday use. Calculate BMI, loans, mortgages, age, percentages, tips, discounts, and more. Instant results — no signup required.
17 tools
Age Calculator
Calculate exact age in years, months, and days from any birth date. Shows total months, weeks, and days lived. Also calculates age on a specific future or past date.
Percentage Calculator
Calculate percentage of a number, percentage change between two values, and find the original number from a percentage. Three calculators in one, no confusing math required.
BMI Calculator
Calculate your Body Mass Index from height and weight. Shows your BMI number and weight category from underweight to obese. Supports both metric (kg/cm) and imperial (lbs/in) units.
Unit Converter
Convert between common units: length, weight, temperature, area, volume, speed, and time. Real-time conversion as you type. Covers metric and imperial with one-click unit swapping.
Number Base Converter
Convert numbers between binary, octal, decimal, and hexadecimal. See all four bases at once when you type a number in any format. Includes hex color reference.
Roman Numeral Converter
Convert Roman numerals to numbers and numbers to Roman numerals. Handles values up to 3,999,999 with proper vinculum notation. Quick reference for dates and page numbers.
Loan Calculator
Calculate monthly loan payments including interest and principal. See full amortization schedule showing how much goes to interest vs principal each month. Adjust loan amount, rate, and term.
Mortgage Calculator
Estimate your monthly mortgage payment including principal, interest, property tax, and insurance. See total cost over the loan term and how extra payments shorten it.
Calorie Calculator
Estimate daily calorie needs based on age, weight, height, and activity level. Uses the Mifflin-St Jeor equation. Shows maintenance calories plus targets for weight loss or gain.
ROI Calculator
Calculate return on investment as a percentage and dollar amount. Enter initial investment and final value. Also computes annualized ROI for multi-year comparisons.
Compound Interest Calculator
See how compound interest grows your money over time. Adjust principal, monthly contributions, rate, and compounding frequency. Shows year-by-year breakdown.
Income Tax Calculator
Estimate take-home pay after federal, state, and FICA taxes. Enter gross salary and filing status. See breakdown of each tax type and your effective tax rate. US brackets only.
Tip Calculator
Calculate tip amount and split the bill evenly. Choose common percentages or enter a custom amount. Shows per-person cost including tip. Rounds results for easy cash payments.
Discount Calculator
Calculate the final price after a percentage or dollar discount. Shows savings amount and discounted total. Works both ways — enter the sale price to find the discount percentage.
Pregnancy Due Date Calculator
Estimate your due date from the first day of your last period. Shows week-by-week trimester breakdown and key milestones. Uses Naegele rule with a 28-day cycle assumption.
Random Number Generator
Generate random numbers within a range. Set minimum, maximum, and count. Option to allow or exclude repeats. Good for raffles, sampling, and testing.
Perpetual Calendar
Browse any month from any year. Shows world holidays, week numbers, moon phases, and notable historical events for each date. Search for a specific date or jump to any month.