All calculators
110 free tools, grouped by what you are trying to work out.
Finance
Loans, savings, investment and tax
Loan EMI Calculator Monthly instalment, total interest and a full amortization schedule for any loan. Compound Interest Calculator Grow a lump sum at any compounding frequency and see the year-by-year path. Simple Interest Calculator Interest charged only on the original principal — the straight-line case. SIP Calculator Project a monthly investment plan, including annual step-ups. SWP Calculator Withdraw monthly from a corpus and see how long it lasts. Retirement Calculator How large a corpus you need, and whether your saving rate gets you there. Inflation Calculator What an amount will be worth later — or what it was worth before. Discount Calculator Sale price, amount saved, and stacked or double discounts. Sales Tax & VAT Calculator Add tax to a price or strip it out of a tax-inclusive total. Tip & Bill Split Calculator Tip, total and the per-person share for any group size. Break-Even Calculator Units and revenue needed to cover fixed and variable costs. Profit Margin & Markup Calculator Margin, markup and profit from cost and price — the two are not the same. CAGR Calculator The single annual growth rate that connects a starting value to an ending one. Salary Converter Convert pay between hourly, daily, weekly, monthly and annual. Loan Payoff Calculator What paying a little extra each month does to your term and total interest. ROI Calculator Return on investment as a percentage of what you put in, annualised over the holding period. APY Calculator Turns a nominal interest rate into the effective annual yield, so two quoted rates can be compared honestly. Present Value Calculator What a future sum is worth in today’s money, discounted at a rate you choose. Future Value Calculator What a lump sum, regular deposits, or both together grow to at a given rate. NPV Calculator Net present value of a series of cash flows, discounted at your cost of capital. IRR Calculator The internal rate of return — the discount rate at which a project’s net present value is exactly zero. XIRR Calculator Annualised return for cash flows on irregular dates — the measure a real portfolio needs. WACC Calculator Weighted average cost of capital, blending equity and after-tax debt by their share of the total. Car Depreciation Calculator What a vehicle is worth after each year, on a declining balance rather than a straight line.
Health & Fitness
Body composition, energy and training
BMI Calculator Body mass index, its category, and the healthy weight range for your height. Calorie & TDEE Calculator Daily energy needs from BMR and activity, with targets for losing or gaining. Macro Calculator Split a calorie target into protein, carbs and fat in grams. Body Fat Calculator US Navy tape-measure body fat percentage, plus lean mass. Ideal Weight Calculator Four clinical formulas plus the healthy BMI range for your height. Water Intake Calculator Daily hydration target from bodyweight and exercise duration. Pregnancy Due Date Calculator Estimated due date, current week and trimester from your last period. Ovulation Calculator Fertile window and next period from your cycle length. Heart Rate Zone Calculator Maximum heart rate and the five training zones. One Rep Max Calculator Estimated 1RM from a set, plus a full percentage training table. Running Pace Calculator Pace, speed and finish times for any distance, in both kilometres and miles.
Mathematics
Algebra, geometry, powers and number theory
Percentage Calculator Every common percentage question in one place — of, change, and reverse. Geometry Calculator Area, perimeter, volume and surface area for common 2D shapes and 3D solids. Ratio Calculator Simplify ratios, scale them, and solve proportions for a missing term. GPA Calculator Credit-weighted grade point average on the standard 4.0 scale. Number Base Converter Convert between binary, octal, decimal and hexadecimal. Scientific Calculator A full expression calculator with functions, constants and precedence. Fraction Calculator Add, subtract, multiply and divide fractions, with the result in lowest terms. LCM & GCD Calculator Lowest common multiple and greatest common divisor for any list of whole numbers. Quadratic Equation Solver Roots, discriminant and vertex for ax² + bx + c = 0, including complex roots. Roman Numeral Converter Numbers to Roman numerals and back, with the rules that make one valid. Number to Words Converter Write any number out in words, in the international or Indian numbering system. Exponent Calculator Raises any base to any power, including negative and fractional exponents, and shows the working. Square Root Calculator Square roots, cube roots and any nth root, with the exact value when the root is a whole number. Logarithm Calculator Logarithms to base 10, base e, base 2 or any base you choose, with the change-of-base working. Scientific Notation Converter Converts between ordinary numbers and scientific, engineering and E notation. Weighted Average Calculator Averages values that do not count equally — grades by credit, prices by quantity, scores by weight. Proportion Calculator Solves a : b = c : d for whichever term you leave blank, by cross-multiplication. Significant Figures Calculator Counts the significant figures in a number and rounds it to as many as you need. Trigonometry Calculator All six trigonometric ratios for an angle, the inverse functions, and a full right-triangle solver. Percent to Fraction Converter Converts between percentages, fractions and decimals, in every direction, in lowest terms.
Statistics & Probability
Distributions, inference and correlation
Z-Score Calculator How many standard deviations a value sits from the mean, and the percentile that implies. Normal Distribution Calculator Probabilities under a bell curve — below, above or between two values. Binomial Distribution Calculator The chance of k successes in n independent trials, exactly or cumulatively. Confidence Interval Calculator The range a population mean is likely to fall in, using the t-distribution for small samples. Margin of Error Calculator The ± figure quoted with a survey result, from its sample size and confidence level. Sample Size Calculator How many responses a survey needs for a given margin of error and confidence level. Correlation Coefficient Calculator Pearson’s r for two data sets, with the least-squares line and how much variance it explains. P-Value Calculator Converts a z or t test statistic into a p-value, one-tailed or two-tailed. Percent Error Calculator How far a measurement falls from the accepted value, as a percentage. Outlier Calculator Finds outliers by Tukey’s method — anything beyond 1.5 interquartile ranges from the quartiles. Statistics Calculator Mean, median, mode, range, variance and standard deviation for a data set. Probability Calculator Single and combined event probability, plus odds conversion. Permutation & Combination Calculator nPr, nCr and factorials, with the ordering distinction made clear.
Date & Time
Ages, durations and working days
Age Calculator Exact age in years, months and days — plus zodiac, birthstone and next birthday. Date Difference Calculator The span between two dates in years, months, days, weeks and hours. Add or Subtract Days Calculator Find the date a given number of days, weeks, months or years away. Working Days Calculator Business days between two dates, excluding weekends and holidays. Time Duration Calculator Add up hours and minutes, or find the gap between two clock times. Unix Timestamp Converter Converts epoch time to a readable date and back, detecting seconds, milliseconds or microseconds. Time to Decimal Converter Turns hours and minutes into decimal hours for payroll, and back again. Military Time Converter Converts between the 24-hour clock and 12-hour AM/PM, including the midnight and noon traps. Timesheet Calculator Adds up a week of shifts with breaks, in hours and minutes and in decimal hours. Time Zone Converter Converts a time between any two zones, following daylight saving on the date you pick.
Converters
Units, bases and data sizes
Unit Converter Length, weight, volume, area, speed, temperature, data and more. Temperature Converter Celsius, Fahrenheit and Kelvin, all at once. Cooking Measurement Converter Cups, spoons, grams and millilitres, with ingredient-aware weights. Cups to Grams Converter Converts cups to grams for a specific ingredient, because a cup of flour and a cup of honey are not the same weight.
Everyday
Bills, fuel, energy and shopping
Fuel Cost & Mileage Calculator Trip cost, fuel economy in every common unit, and cost per kilometre. Electricity Cost Calculator What an appliance costs to run per day, month and year. Solar Panel Calculator System size, output and payback period for rooftop solar. Speed, Distance & Time Calculator Solve for whichever of speed, distance or time you are missing.
Home & Construction
Materials, paint, tiles and land
Physics
Motion, energy, electricity and gases
Ohm’s Law Calculator Solves voltage, current, resistance and power from any two of them. Kinetic Energy Calculator The energy of a moving object, ½mv², in joules — and why doubling speed quadruples it. Potential Energy Calculator Gravitational potential energy, mgh, and the speed it becomes if the object falls. Momentum Calculator Linear momentum, p = mv, plus the impulse needed to stop it in a given time. Force Calculator Newton’s second law, F = ma, with the weight of the same mass for comparison. Acceleration Calculator Acceleration from a change in speed over a time or a distance, with the full motion solved. Density Calculator Density from mass and volume, in kg/m³ and g/cm³, with whether it floats in water. Pressure Calculator Pressure from a force spread over an area, in pascals, bar, psi and atmospheres. Half-Life Calculator How much of a decaying quantity remains after a given time, or the half-life implied by a measured drop. Ideal Gas Law Calculator Solves PV = nRT for pressure, volume, moles or temperature — leave one blank. Joules to Watts Converter Energy and power are not the same unit — this converts between them using the time involved.
Tech & Media
Screens, files, bandwidth and colour
Aspect Ratio Calculator Simplify a resolution and resize while keeping proportions exact. Data Storage Converter Bits and bytes through petabytes, in both decimal (GB) and binary (GiB) — side by side, never mixed. Download Time Calculator How long a file takes at a given connection speed. Video & Audio File Size Calculator Estimate file size from bitrate and duration, or the bitrate to hit a size. IP Subnet Calculator Network address, broadcast, usable host range and mask from CIDR. Password Strength Calculator Entropy in bits and how long a brute-force attack would take. Word & Character Counter Words, characters, sentences and reading time for any block of text. Hex to Decimal Converter Converts hexadecimal to decimal and back, with binary and octal alongside. Binary to Decimal Converter Converts binary to decimal and back, showing the bit weights that produce the answer. Hex to Binary Converter Converts hexadecimal to binary and back — each hex digit is exactly four bits. Mbps to MB/s Converter Converts a connection speed in megabits to a download speed in megabytes, and gives the transfer time.