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Loan payments, compound interest, take-home pay, BMI, dates and unit conversions. Every calculator shows the formula and a worked example, and updates as you type. 50 calculators6 categories
50 of 50 calculators
Area Converter Convert area between square metres, square feet, square yards, acres, hectares, square kilometres and square milesElectricity Cost Calculator Calculate what an appliance costs to run from its wattage, hours of use per day, days and your electricity price per kWhFuel Cost & MPG Calculator Calculate the fuel needed and the cost of a trip from distance, miles per gallon and the price of fuelLength Converter Convert length and distance between metres, kilometres, miles, yards, feet, inches, centimetres and millimetres with exact conversion factorsPaint Quantity Calculator Calculate paint needed from room dimensions, coats, coverage per gallon and openings — in gallons, cans and costSpeed Converter Convert speed between miles per hour, kilometres per hour, metres per second, knots and feet per secondTemperature Converter Convert between Celsius, Fahrenheit and Kelvin instantly, with the formulas for each direction and a worked exampleTile Quantity Calculator Calculate the number of tiles for a floor or wall from the area, tile size, waste allowance and price per square footVolume Converter Convert volume between litres, millilitres, cubic metres, US gallons, quarts, cups and fluid ounces, with US and imperial differences notedWeight Converter Convert weight between kilograms, pounds, ounces, grams, milligrams and stones using exact conversion factorsAge Calculator Calculate your exact age in years, months and days on any date, plus total days lived and the date of your next birthdayBusiness Days Calculator Add or count business days from a start date, skipping weekendsCountdown Calculator Count the days, weeks and business days until an event or deadlineDate Difference Calculator Calculate the number of days, weeks, months and business days between two datesTime Duration Calculator Calculate the hours and minutes between two times, minus any breakBMI Calculator Calculate your body mass index from your weight and height, see the WHO category and the healthy weight range for your heightBMR Calculator Calculate your basal metabolic rate with the Mifflin-St Jeor equation: the calories your body burns at complete rest, by weight, height, age and sexIdeal Weight Calculator Find a healthy weight range for your height from BMI thresholds, plus a BMI 22 target weightNavy Body Fat Calculator Estimate body fat percentage from height, neck, waist and hip measurements using the US Navy formula, with a category rangeOvulation Calculator Estimate ovulation day, the fertile window and the next period from your last period date and typical cycle lengthPregnancy Due Date Calculator Estimate a pregnancy due date from the first day of your last period and cycle length, using Naegele's rule, plus the estimated conception dateTDEE Calculator Calculate total daily energy expenditure from your BMR and activity level, with calorie targets for losing, maintaining and gaining weight401(k) Growth Calculator Project your 401(k) balance including employer matching contributionsAPY vs APR Calculator Convert a nominal APR into the effective annual rate (APY) for any compounding frequency, and see what the difference is worth on a real balanceCAGR Calculator Calculate compound annual growth rate from a starting value, ending value and number of yearsCompound Interest Calculator See what compound interest does to a starting balance plus regular monthly contributionsInflation Calculator See what inflation does to prices and to the value of your money over timeROI Calculator Calculate return on investment, net profit and the equivalent annualised return for any investment or projectRetirement Nest Egg Calculator Project your retirement balance from current savings, monthly contributions, expected returns and years to retirementSavings Goal Calculator Find out how many months it takes to reach a savings target from your current balance, monthly deposits and interest rate — and how much of it is interestSimple Interest Calculator Calculate simple interest on a principal amount at a fixed rate for a chosen number of years, including the total balance and the monthly interest equivalentAuto Loan Calculator Calculate a car loan payment from the vehicle price, down payment, trade-in value, APR and termCredit Card Payoff Calculator See how long a credit card balance takes to clear at a fixed monthly payment, and how much interest you payLoan Payment Calculator Work out the monthly payment, total repayment and total interest on any fixed-rate loanMortgage Affordability Calculator Estimate the home price you can afford from your income, existing debts and down payment, using the standard 28/36 debt-to-income rules lenders applyMortgage Amortisation Calculator See exactly how a fixed-rate mortgage is paid down: monthly payment, first-month principal and interest, and a year-by-year amortisation schedule down to a zero balanceMortgage Payment Calculator Calculate the principal-and-interest payment on a fixed-rate mortgage, plus total interest and total costRefinance Break-Even Calculator Find the break-even point of a refinance from the new payment, closing costs and the months until the monthly savings repay the feesRent vs Buy Calculator Compare the real cost of renting and buying over the same number of years, including mortgage interest, taxes, insurance, maintenance, rent increases and home equityStudent Loan Calculator Calculate the standard repayment payment on a student loan and see total interestDiscount Calculator Calculate a percentage discount, the money saved and the final price — with optional sales tax on topGST Calculator Calculate GST on a net price or extract it from a GST-inclusive totalHourly to Salary Calculator Convert an hourly wage into annual, monthly, weekly and daily salary using your real weekly hours and weeks worked per yearOvertime Pay Calculator Calculate overtime pay at time and a half or any multiplier, plus regular pay and total weekly gross pay from your hourly ratePaycheck Net Estimate Calculator Estimate US take-home pay from a gross salary using 2025 federal brackets, FICA, state tax and pre-tax 401(k) contributionsRaise Calculator Work out your new salary after a percentage raise, the annual increase and the extra money per month and per paycheckSalary to Hourly Calculator Convert an annual salary into an hourly, weekly and monthly rate based on your real working hours and paid weeksSales Tax Calculator Add US sales tax to a price, or work out how much tax is inside a tax-inclusive totalTip & Bill Split Calculator Calculate the tip on a bill, the total and how much each person owes when splitting between friendsVAT Calculator Add VAT to a net price or extract the VAT from a VAT-inclusive amount
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How these calculators work
Each tool is a self-contained page with a form and a live result. The arithmetic runs in your browser — nothing you type is sent anywhere — and the same formula is printed on the page so you can check it yourself. The server-rendered result means the page shows a useful answer even before the script runs.
Why the numbers can differ elsewhere
Calculators disagree when they use different assumptions: tax years, compounding frequency, rounding, or extras such as fees and insurance. Each page here states its assumptions and shows a worked example with the default inputs, so you can see exactly what is included.