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Popular: mortgage, compound interest, BMI, percentage
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Each calculator explains the formula, shows a worked example, and keeps your inputs on your device.
Mortgage Calculator
Estimate your monthly mortgage payment, total interest, and total repayment from the home price, down payment, rate, and term.
Open calculatorLoan Payment Calculator
Calculate a fixed monthly loan payment and see the total interest charged over the full term.
Open calculatorCompound Interest Calculator
Project investment growth with compound interest, recurring monthly deposits, and a chosen compounding frequency.
Open calculatorSimple Interest Calculator
Find simple interest and final balance using principal, annual rate, and time.
Open calculatorSavings Goal Calculator
Estimate the monthly deposit needed to reach a savings target with interest by a chosen deadline.
Open calculatorRetirement Calculator
Project your retirement balance from current savings, monthly contributions, return, and time horizon.
Open calculatorROI Calculator
Measure return on investment as a dollar gain and percentage of the original cost.
Open calculatorSales Tax Calculator
Calculate sales tax and the after-tax total for any purchase amount and tax rate.
Open calculatorDiscount Calculator
Find the sale price and amount saved after applying a percentage discount.
Open calculatorTip Calculator
Split a bill and tip fairly by calculating the tip, grand total, and amount per person.
Open calculatorBMI Calculator
Calculate adult body mass index and its standard weight-status category from height and weight.
Open calculatorCalorie Calculator
Estimate daily calorie needs from age, sex, height, weight, and activity level using the Mifflin–St Jeor equation.
Open calculatorBody Fat Calculator
Estimate body fat percentage with the U.S. Navy circumference method.
Open calculatorIdeal Weight Calculator
Estimate an adult reference weight range from height using the Devine formula and healthy BMI bounds.
Open calculatorWater Intake Calculator
Estimate a practical daily water target based on body weight and exercise time.
Open calculatorPercentage Calculator
Quickly find what a given percentage of any number equals.
Open calculatorPercentage Change Calculator
Measure the percentage increase or decrease between an original and a new value.
Open calculatorFraction Calculator
Add, subtract, multiply, or divide two fractions and receive a simplified answer.
Open calculatorAverage Calculator
Find the arithmetic mean, sum, count, minimum, and maximum of a list of numbers.
Open calculatorRatio Calculator
Simplify a two-number ratio to its lowest whole-number form.
Open calculatorScientific Calculator
Evaluate common arithmetic, powers, roots, trigonometry, and logarithms with a safe on-page expression tool.
Open calculatorAge Calculator
Calculate exact age in years, months, and days from a birth date to a chosen date.
Open calculatorDate Difference Calculator
Count the exact number of days and approximate weeks between any two dates.
Open calculatorTime Duration Calculator
Find elapsed hours and minutes between two clock times, including overnight spans.
Open calculatorGPA Calculator
Calculate a weighted grade point average from course grades and credit hours.
Open calculatorUnit Converter
Convert common length, weight, and temperature measurements with one simple tool.
Open calculatorFuel Cost Calculator
Estimate trip fuel usage, total fuel cost, and cost per traveler.
Open calculatorElectricity Cost Calculator
Estimate an appliance’s electricity use and cost from wattage, run time, and utility rate.
Open calculatorPaint Calculator
Estimate wall area and gallons of paint needed from room dimensions, coats, and coverage.
Open calculatorPace Calculator
Calculate running pace per mile and per kilometer from distance and finish time.
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The formula is never a black box.
We show how every result is calculated, include practical examples, and explain where estimates have limits.