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101 free calculators & converters — instant answers, no sign-up, no clutter.
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Financial
Loan Calculator
Monthly payment, total interest, and a full amortization schedule.
Compound Interest Calculator
See how savings grow with compound interest and monthly contributions.
Simple Interest Calculator
Calculate simple interest and total repayment on a principal.
Discount Calculator
Find the sale price and how much you save from a percentage discount.
Sales Tax Calculator
Add sales tax to a price to get the tax amount and final total.
Tip Calculator
Calculate the tip, total, and amount per person when splitting a bill.
Mortgage Calculator
Estimate your full monthly mortgage payment including principal, interest, taxes and insurance.
Retirement Calculator
Project your retirement savings from your current age, contributions and expected return.
Auto Loan Calculator
Estimate your monthly car payment with down payment, trade-in, sales tax and APR.
Debt Payoff Calculator
See how long to pay off a credit card or loan, total interest, and the power of extra payments.
CAGR Calculator
Compound annual growth rate from start value, end value and years, with Rule of 72.
VAT Calculator
Add VAT to a net price or extract it from a gross amount at any rate.
Salary to Hourly Calculator
Convert between hourly, weekly, monthly and annual pay with your real hours.
Savings Goal Calculator
How much to save monthly to reach a goal by a deadline, with or without interest.
Margin Calculator
Profit margin and markup from cost and price, or price from a target margin.
50/30/20 Budget Calculator
Split monthly take-home pay into needs, wants and savings with the 50/30/20 rule.
Credit Card Payoff Calculator
Months to clear a card balance at your APR, total interest, and faster-payoff savings.
Rent Affordability Calculator
How much rent fits your income with the 30% rule, adjusted for debts.
Break-Even Calculator
Units and revenue needed to cover fixed costs, plus profit at any volume.
APR Calculator
The effective APR of a loan once upfront fees are included, vs the quoted rate.
Fitness & Health
BMI Calculator
Body Mass Index from height and weight, metric or imperial.
Calorie (TDEE) Calculator
Estimate your BMR and daily calorie needs using the Mifflin-St Jeor equation.
Due Date Calculator
Estimate your pregnancy due date, current week and trimester from your last period.
Body Fat Calculator
Estimate your body fat percentage using the U.S. Navy circumference method.
One Rep Max Calculator
Estimate your one-rep max from a lift and see training weights for every percentage.
Running Pace Calculator
Find your pace per mile and per km, plus speed, from a distance and finish time.
Ideal Weight Calculator
Estimate your ideal body weight using the Devine, Robinson and Hamwi formulas.
BMR Calculator
Basal metabolic rate via Mifflin-St Jeor, plus Katch-McArdle from body fat.
Macro Calculator
Turn a calorie target into protein, carb and fat grams with preset or custom splits.
Lean Body Mass Calculator
Fat-free mass from height, weight and sex by three published formulas.
Waist-to-Hip Ratio Calculator
Waist-to-hip ratio with WHO risk categories for men and women.
Pregnancy Week Calculator
Current pregnancy week, trimester and countdown from LMP or due date.
Heart Rate Zone Calculator
Five training zones from age, personalized with resting HR via Karvonen.
Calories Burned Calculator
Calories burned for 40+ activities from published MET values.
Steps to Miles Calculator
Convert step count to miles/km via height-based stride, with calories.
Math
Quadratic Formula Calculator
Solve ax² + bx + c = 0 with real or complex roots and the discriminant.
Standard Deviation Calculator
Compute mean, variance, and population/sample standard deviation for a data set.
Percentage Calculator
Find X% of a number, what percent one number is of another, and percent change.
Percentage Change Calculator
Percent increase or decrease between two values, plus symmetric percentage difference.
Fraction Calculator
Fraction arithmetic with simplified results, mixed numbers and steps.
Fraction to Decimal Converter
Fractions to decimals with repeating blocks detected, and decimals back to fractions.
Average Calculator
Mean, median, mode, range, sum and count from any pasted number list.
Ratio Calculator
Simplify ratios, solve A:B = C:? proportions, and scale recipes or mixes.
Final Grade Calculator
The exact final-exam score you need for your target course grade.
Grade Calculator
Weighted course grade from scores and category weights, with letter grade.
Sig Fig Calculator
Round to significant figures or decimal places, with input precision counted.
Square Root Calculator
Square, cube and nth roots plus powers, with simplified radical forms.
Slope Calculator
Slope, y-intercept, line equation, distance and midpoint from two points.
Triangle Calculator
Solve triangles from three sides or right-triangle legs — angles, area, type.
Circle Calculator
Enter any circle measurement and get the other three instantly.
Volume Calculator
Volume of five solids in m³, ft³, liters and gallons at once.
GCF & LCM Calculator
Greatest common factor and least common multiple with prime factorizations.
Prime Factorization Calculator
Prime factors, factor pairs and primality check for any whole number.
Probability Calculator
Exact probabilities for coins, dice, and nCr/nPr counting problems.
Z-Score Calculator
Z-score and percentile on the normal curve from value, mean and SD.
Scientific Calculator
Full expression evaluation with trig, logs, powers, DEG/RAD and ANS chaining.
Construction
Concrete Calculator
Cubic yards, pre-mixed bags, and cost for a concrete slab.
Paint Calculator
Estimate how many gallons of paint you need from room size and coats.
Tile Calculator
Work out how many tiles and boxes you need for a floor or wall.
Square Footage Calculator
Calculate the square footage of a room or lot and estimate material or flooring cost.
Gravel Calculator
Estimate the gravel needed for a driveway or area in cubic yards, tons and cost.
Mulch Calculator
Mulch or topsoil from bed size and depth — yards, bags and cost.
Drywall Calculator
Drywall sheets, screws and joint compound from room dimensions.
Roof Pitch Calculator
Pitch (X/12), angle and rafter length from rise and run.
Board Foot Calculator
Board feet and cost from lumber dimensions and piece count.
Stair Calculator
Equal steps, riser height, tread and stringer from total rise.
Everyday & Conversions
GPA Calculator
Calculate your grade point average from letter grades and credit hours.
Dog Age Calculator
Dog years to human years with modern size-adjusted veterinary formulas.
Cat Age Calculator
Cat years to human years with the veterinary 15+9+4 life-stage model.
Random Number Generator
Crypto-grade random numbers in any range, with or without repeats.
Dice Roller
Roll any dice combo in D&D notation with modifiers and fair randomness.
Bill Split Calculator
Split bills evenly or by weighted shares, exact to the cent.
Date & Time
Age Calculator
Find your exact age in years, months, days — plus total weeks, days and hours.
Time Duration Calculator
Calculate the exact duration between two dates and times.
Work Hours Calculator
Add up worked hours from a start and end time, minus breaks, in decimal and HH:MM.
Date Calculator
Find the days between two dates, or add and subtract days, weeks, months and years.
Days Until Calculator
Days, weeks and working days until any date — or days since a past one.
Military Time Converter
24-hour military time to standard time and back, with a full chart.
Unix Timestamp Converter
Epoch seconds/millis to dates and back, with a live current ticker.
Time Zone Converter
Convert times between zones with IANA data — DST handled automatically.
Unit Converters
Temperature Converter
Convert instantly between Celsius, Fahrenheit and Kelvin.
Length Converter
Convert between millimeters, centimeters, meters, kilometers, inches, feet, yards and miles.
Weight Converter
Convert between kilograms, grams, pounds, ounces, stone and tonnes.
Fuel Cost Calculator
Estimate the fuel cost and gallons for a trip from distance, MPG and gas price.
Speed Converter
Convert between miles per hour, kilometers per hour, meters per second, knots and feet per second.
Cooking Converter
Convert recipe amounts between cups, grams, milliliters and spoons by ingredient.
Area Converter
Convert area between square feet, meters, yards, acres, hectares and more.
Science & Space
Sleep Calculator
Find the best bedtime or wake-up time based on 90-minute sleep cycles.
Weight on Planets
See how much you would weigh on the Moon, Mars, Jupiter and every other planet.
Age on Planets
Find out how old you are on Mercury, Mars, Jupiter and beyond, based on orbital years.
Wind Chill & Heat Index
Feels-like temperature via official NWS formulas with risk bands.
Text & Code
Number Base Converter
Convert numbers between binary, octal, decimal and hexadecimal instantly.
Morse Code Translator
Translate text to Morse code and decode Morse code back to text.
Password Generator
Strong random passwords generated locally with crypto-grade randomness.
Word Counter
Words, characters, sentences and reading/speaking time, live as you type.
Roman Numeral Converter
Numbers to Roman numerals and back, 1–3999, with strict validation.
Binary Translator
Text to binary or hex and back with UTF-8, full Unicode support.
Aspect Ratio Calculator
Scale dimensions keeping the ratio, with platform presets and preview.
Color Converter
HEX, RGB and HSL conversions with live swatch and WCAG contrast.
Typing Speed Test
60-second typing test: WPM, accuracy and a locally saved personal best.
Subnet Calculator
Network, broadcast, host range and count from any IPv4 + CIDR prefix.