50 practical tools
Free online calculators and converters
Find calculators for money, borrowing, pay, shopping, everyday math, measurements, dates, time, and common U.S. and metric conversions.
Money and borrowing
Mortgage, auto loan, debt, credit-card, and borrowing tools.
Mortgage Calculator
Estimate a monthly mortgage payment with taxes, insurance, PMI, HOA dues, and extra principal.
Home price, down payment, interest rate, loan term, recurring housing costs, and amortization.Auto Loan Calculator
Estimate a car payment, amount financed, total interest, and total loan cost.
Vehicle price, down payment, trade-in, sales tax, APR, and loan term.Loan Payment Calculator
Estimate monthly payments and total interest for a fixed-rate installment loan.
Loan amount, interest rate, term, extra principal, total repayment, and amortization.Amortization Calculator
Break a fixed-rate loan into monthly principal and interest over time.
Monthly payment, total interest, payoff length, and the changing principal-to-interest mix.Credit Card Payoff Calculator
Estimate how long it will take to pay off a credit-card balance and how much interest you may pay.
Balance, APR, monthly payment, estimated payoff date, and higher-payment comparisons.Debt Payoff Calculator
Estimate payoff time and interest for a debt with a fixed monthly payment.
Starting balance, annual interest rate, monthly payment, months to payoff, and total paid.Debt-to-Income Ratio Calculator
Calculate the share of gross monthly income that goes toward monthly debt payments.
Gross monthly income, recurring debt payments, DTI percentage, and remaining income before other expenses.Income and saving
Pay, overtime, savings, interest, CDs, and return calculations.
APY Calculator
Convert a stated interest rate and compounding frequency into annual percentage yield.
Nominal annual rate, compounding frequency, effective annual yield, and one-year interest on an example balance.2026 Paycheck Calculator
Estimate take-home pay after federal withholding, Social Security, Medicare, and entered deductions.
2026 federal withholding method, W-4 inputs, payroll taxes, deductions, and manual state or local withholding.Hourly to Salary Calculator
Convert an hourly wage into annual, monthly, biweekly, weekly, and daily gross pay.
Hourly rate, hours per week, weeks per year, annual work hours, and periodic gross pay.Salary to Hourly Calculator
Convert an annual salary into an equivalent hourly rate and periodic gross pay.
Annual salary, weekly hours, working weeks, hourly equivalent, and weekly or monthly gross pay.Overtime Pay Calculator
Estimate regular pay, overtime pay, and total weekly gross pay.
Hourly rate, regular hours, overtime hours, and an adjustable overtime multiplier.Commission Calculator
Calculate commission earnings and total pay from sales and a commission rate.
Sales amount, commission percentage, optional base pay, commission earned, and combined pay.Compound Interest Calculator
Project account growth with compound interest and recurring contributions.
Starting balance, contributions, interest rate, compounding frequency, and year-by-year growth.Simple Interest Calculator
Calculate interest using principal, annual rate, and time without compounding.
Principal, simple annual interest rate, time period, interest earned or charged, and ending total.Savings Goal Calculator
Estimate the monthly contribution needed to reach a savings target by a chosen date.
Current savings, target amount, annual return, time horizon, and required monthly contribution.Savings Interest Calculator
Estimate how a savings balance can grow from interest over time.
Starting balance, annual interest rate, compounding frequency, ending balance, and interest earned.CD Calculator
Estimate the ending balance and interest earned on a certificate of deposit using APY.
Opening deposit, APY, term in months, maturity value, and estimated interest earned.ROI Calculator
Calculate return on investment from an initial cost and ending value.
Initial investment, final value, profit or loss, ROI percentage, and investment multiple.Shopping and everyday
Tips, sales tax, discounts, unit prices, fuel costs, and gas mileage.
Sales Tax Calculator
Add sales tax to a price or reverse a tax-inclusive total using the rate you enter.
Pre-tax price, tax amount, checkout total, and reverse sales-tax calculation.Tip Calculator and Bill Splitter
Calculate a restaurant tip, total bill, and equal per-person split.
Tip percentage, tip amount, bill total, per-person share, and exact cent reconciliation.Discount Calculator
Calculate the sale price and dollar savings from a percentage discount.
Original price, discount percentage, amount saved, final price, and price paid as a share of original.Markup Calculator
Calculate selling price and profit from product cost and a markup percentage.
Cost, markup percentage, profit per unit, selling price, and gross margin equivalent.Margin Calculator
Calculate gross margin and markup from cost and selling price.
Cost, selling price, gross profit, margin percentage, and markup percentage.Unit Price Calculator
Compare package prices by calculating the cost per unit.
Package price, quantity, unit price, and optional comparison between two package sizes.Fuel Cost Calculator
Estimate fuel used and trip cost from distance, MPG, and gas price.
Trip miles, vehicle fuel economy, gas price, gallons needed, and estimated fuel cost.MPG Calculator
Calculate miles per gallon from miles driven and gallons used.
Distance, fuel used, MPG, gallons per 100 miles, and optional fuel cost per mile.Math and measurement
Percentages, fractions, averages, ratios, areas, volumes, and measurements.
Percentage Calculator
Solve percent-of, what-percent, percentage-change, and reverse-percentage questions.
Four common percentage calculations with direct formulas and plain-English explanations.Fraction Calculator
Add, subtract, multiply, or divide two fractions and simplify the result.
Two fractions, arithmetic operation, simplified fraction, improper fraction, and decimal value.Average Calculator
Find the arithmetic mean, total, count, minimum, and maximum of a list of numbers.
Enter numbers separated by commas or spaces to calculate common summary statistics.Ratio Calculator
Simplify a two-number ratio and calculate its equivalent decimal relationship.
Two values, greatest common divisor, simplified ratio, and A-to-B decimal value.Decimal to Fraction Calculator
Convert a decimal value into a simplified fraction.
Decimal input, rational approximation, simplified numerator and denominator, and percentage equivalent.Random Number Generator
Generate one or more random whole numbers within a range you choose.
Minimum, maximum, quantity, inclusive range, and a one-click regenerate action.Square Footage Calculator
Calculate floor or surface area in square feet from length and width.
Length and width in feet, square feet, square yards, and square meters.Area Calculator
Calculate the area of a rectangle, triangle, or circle.
Choose a shape and enter the relevant dimensions to get area in square units.Volume Calculator
Calculate the volume of a rectangular box or cylinder.
Choose a shape, enter dimensions, and get volume in cubic units.Dates and time
Age, date differences, countdowns, shift hours, and time duration.
Age Calculator
Calculate age from a birth date to a selected date.
Years, months, and days of age plus total days between the two dates.Date Difference Calculator
Calculate the number of days and weeks between two dates.
Start date, end date, signed day difference, absolute days, and weeks plus days.Date Add/Subtract Calculator
Add or subtract a number of days from a calendar date.
Starting date, positive or negative day offset, resulting date, and day of week.Time Duration Calculator
Calculate elapsed time between two clock times, including overnight spans.
Start time, end time, same-day or next-day option, total hours, minutes, and decimal hours.Hours Worked Calculator
Calculate paid work hours from start time, end time, and an unpaid break.
Shift start, shift end, optional overnight shift, break minutes, and paid decimal hours.Days Until Calculator
Count the days from today to a target date.
Target date, days remaining or elapsed, weeks and days, and the target weekday.Conversions
Fast temperature, length, weight, and distance conversions.
Fahrenheit to Celsius Converter
Convert Fahrenheit temperatures to Celsius using the exact linear relationship.
Two-way temperature conversion with useful weather, cooking, and reference temperatures.Celsius to Fahrenheit Converter
Convert Celsius temperatures to Fahrenheit instantly.
Celsius input, Fahrenheit result, exact conversion formula, and common reference temperatures.Inches to Centimeters Converter
Convert inches to centimeters using the exact international inch definition.
Inches, centimeters, millimeters, and a precise 1 inch = 2.54 centimeters conversion.Centimeters to Inches Converter
Convert centimeters to inches quickly and accurately.
Centimeters, inches, feet plus inches, and the exact 2.54 centimeters per inch relationship.Pounds to Kilograms Converter
Convert pounds to kilograms using the exact international pound definition.
Pounds, kilograms, grams, and a precise 1 pound = 0.45359237 kilograms conversion.Kilograms to Pounds Converter
Convert kilograms to pounds instantly.
Kilograms, pounds, ounces, and the exact international pound conversion factor.Miles to Kilometers Converter
Convert miles to kilometers using the exact international mile relationship.
Miles, kilometers, meters, and a precise 1 mile = 1.609344 kilometers conversion.Kilometers to Miles Converter
Convert kilometers to miles quickly and accurately.
Kilometers, miles, feet, and the exact international mile conversion relationship.A calculator directory built for useful answers
Our Calculator includes 50 tools covering household borrowing, debt, income, saving, shopping, fuel costs, percentages, fractions, measurements, dates, work hours, and unit conversions. Each page starts with the interactive tool, followed by an explanation of how the calculation works and any assumptions that matter.
Financial calculations that depend on regulations, disclosure rules, or official definitions cite primary sources where relevant. See our calculation and editorial methodology for our approach to formulas, rounding, testing, assumptions, and source selection.