All tools / Calculators & Unit Conversion

Free Online Calculators

Choose a calculator for the question you need to answer. Each page shows the result alongside the units, formula, and assumptions used.

45 free toolsNo sign-upBrowser-based

Choose a tool

Start with pay and loan tools for money questions, BMI and pace for personal measurements, or concrete and paint for simple project estimates. Financial and health results are estimates; read each tool's notes before making a decision.

Finance

12 tools

Hourly to Salary CalculatorTurn an hourly rate into a weekly, monthly, and yearly gross salary.Salary to Hourly CalculatorFind the hourly rate behind an annual salary.Compound Interest CalculatorEstimate the future value of savings and monthly deposits.Loan Payoff CalculatorSee how an extra monthly payment changes a payoff date.Loan Repayment CalculatorEstimate a fixed monthly loan payment and total interest.Mortgage Payment CalculatorEstimate principal, interest, tax, insurance, and HOA per month.ROI CalculatorMeasure gain or loss against your initial investment.Auto Loan CalculatorEstimate a vehicle loan payment and total borrowing cost.Sales Tax CalculatorAdd sales tax to a subtotal or find the tax amount.CAGR CalculatorFind the annualized growth rate between two values.VAT CalculatorAdd VAT to a net price or remove it from a gross price.Rent vs Buy CalculatorCompare estimated cash costs over a chosen number of years.

Everyday Math

22 tools

Tip CalculatorCalculate the tip, total bill, and what each person owes.Split Bill CalculatorSplit a shared bill, tax, and tip evenly.Weighted Grade CalculatorFind a course grade from assignment scores and weights.Percent Change CalculatorMeasure an increase or decrease from a starting value.Area ConverterMultiply the input by the source unit factor and divide by the destination factor.Length ConverterMultiply the input by the source unit factor and divide by the destination factor.Pressure ConverterMultiply the input by the source unit factor and divide by the destination factor.Speed ConverterMultiply the input by the source unit factor and divide by the destination factor.Volume ConverterMultiply the input by the source unit factor and divide by the destination factor.Weight ConverterMultiply the input by the source unit factor and divide by the destination factor.Bytes To Megabytes ConverterMultiply the input by the source unit factor and divide by the destination factor.Temperature ConverterConvert the source to Celsius, then convert Celsius to the destination scale.Average CalculatorAdd the finite numbers and divide by their count; also report minimum, maximum and median.Discount CalculatorSavings = original price × discount / 100; sale price = original price − savings.Percentage CalculatorResult = percentage × base amount / 100.Aspect Ratio CalculatorReduce integer width and height by their greatest common divisor; scale height to the target width.DPI CalculatorPixel density = pixel length / printed length in inches.Random Number GeneratorUse rejection sampling on browser cryptographic random bytes to draw unbiased integers.Decimal To Fraction ConverterParse a finite decimal as an integer over a power of ten and reduce it with integer greatest common divisors.Pixel To Inch ConverterPrinted inches = pixel length / pixels per inch.Screen Resolution CalculatorTotal pixels = width × height; PPI = the square root of (width² + height²), divided by diagonal inches.Ratio CalculatorFor a / b = c / x, the missing value is x = b × c / a.

Health & Fitness

5 tools

BMI Calculator OnlineCalculate your adult body mass index from height and weight.Pregnancy Due Date CalculatorEstimate a due date from the first day of your last period.Running Pace CalculatorTurn a finish time and distance into pace and speed.Calorie Deficit CalculatorEstimate daily maintenance energy and a lower intake target.TDEE CalculatorEstimate adult daily energy expenditure from body measurements and activity.

Education

1 tool

GPA CalculatorCalculate a credit-weighted GPA on a 4.0 scale.

Math & Science

3 tools

Quadratic Equation SolverSolve ax² + bx + c = 0, including complex roots.Scientific Notation ConverterConvert a decimal or exponent value without rounding its digits.Fraction SimplifierReduce an integer fraction to its lowest terms.

Home & DIY

2 tools

Concrete CalculatorEstimate concrete volume for a rectangular slab.Paint CalculatorEstimate paint for four walls of a rectangular room.

How to choose

For a payment question, choose the calculator that matches the amount you know. Hourly to Salary and Salary to Hourly convert gross pay. Loan Repayment starts with a balance, rate, and term; Loan Payoff starts with an existing balance and payment. Mortgage Payment adds the entered tax, insurance, and HOA amounts to principal and interest.

For measurements, enter values in the units printed beside each field. BMI and energy estimates use adult population formulas and cannot assess an individual's health. Concrete and Paint use simple rectangular measurements, so account for unusual shapes separately. Every result shows its formula or assumptions below the form.

Common questions

Are these calculators free to use?

Yes. Each calculator runs in your browser without an account or payment.

Will a financial or health result match a professional quote?

Not necessarily. Rates, fees, exemptions, and personal circumstances can change a real result. Check each tool's stated exclusions.

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