Everyday and math calculators for the questions that come up in daily life and schoolwork: percentages, fractions, ratios, areas and volumes, time and date, tips and discounts, and well over a hundred more.
Each tool is free, shows the formula with a worked example, and many include a diagram. Browse below or search by name.
📐 Statistics & Probability 16
Binomial Distribution CalculatorBinomial probabilities: P(X=k), cumulative, mean, variance.Combination CalculatorCompute combinations C(n, r).Confidence Interval CalculatorConfidence interval for a population mean.Linear Regression CalculatorLeast-squares line of best fit for (x, y) data: slope, intercept, R².Margin of Error CalculatorMargin of error for survey or poll given sample size and confidence.Mean Median Mode CalculatorFind the mean, median, mode, and range of a list of numbers.Normal Distribution CalculatorCumulative and tail probabilities for the standard normal distribution.Percentile CalculatorFind any percentile of a dataset.Permutation CalculatorCompute permutations P(n, r).Probability CalculatorP(A and B), P(A or B), and conditional probability.Quartile / IQR CalculatorQuartiles, IQR, and outliers using Tukey fences.Range CalculatorFind the range (max - min) of a dataset.Sample Size CalculatorRequired sample size for survey margin of error and confidence.Standard Deviation CalculatorCompute sample or population standard deviation.Variance CalculatorCompute sample or population variance.Z-Score CalculatorCompute the z-score of a value relative to mean and SD.
📐 Financial Math 12
APR CalculatorSolve for the implied annual percentage rate (APR) of a loan.CAGR CalculatorCompound annual growth rate between two values over a period.Compound Interest CalculatorSee how a starting amount grows with compound interest.Credit Card Payoff CalculatorSee how long it will take to pay off a credit card balance at a fixed monthly payment.Inflation CalculatorSee how inflation grows future costs and erodes today’s buying power.Investment Growth CalculatorProject the future value of an investment from a starting balance and monthly contributions.Loan CalculatorEstimate the monthly payment and total interest on a fixed-rate loan.Markup / Margin CalculatorMarkup, margin, and profit from cost and selling price.Mortgage CalculatorEstimate a monthly mortgage payment including principal, interest, taxes and insurance.Retirement CalculatorProject a retirement nest egg from current savings, contributions, return, and years.ROI CalculatorCalculate return on investment (ROI) and annualized return.Savings Goal CalculatorFind how much to save each month to hit a savings goal by a target date.
📏 Conversions 12
Area ConverterConvert between square meters, feet, acres, hectares and other area units.Binary / Hex / Decimal ConverterConvert between binary, octal, decimal, and hexadecimal.Currency ConverterConvert between 160+ world currencies using live daily mid-market exchange rates.Data Storage ConverterConvert between bits, bytes, KB, MB, GB, TB and PB in binary or decimal.Energy ConverterConvert between joules, calories, watt-hours, BTU and other energy units.Length ConverterConvert between metric and imperial length units.Mass & Weight ConverterConvert between grams, kilograms, pounds, ounces, stones and tons.Pressure ConverterConvert between pascals, bar, atmospheres, psi, mmHg and other pressure units.Speed ConverterConvert between m/s, km/h, mph, ft/s, knots and Mach.Temperature ConverterConvert between Fahrenheit, Celsius and Kelvin.Time ConverterConvert between milliseconds, seconds, minutes, hours, days, weeks, months and years.Volume ConverterConvert between liters, milliliters, gallons, cups, fluid ounces and other volume units.
📐 Geometry 10
Circle CalculatorFind radius, diameter, circumference, and area of a circle.Cone CalculatorVolume, slant height, and surface area of a cone.Cube CalculatorEdge, volume, surface area, and diagonals of a cube.Cylinder CalculatorVolume, lateral area, and surface area of a cylinder.Polygon CalculatorArea, perimeter, apothem, and angles of any regular polygon.Rectangle CalculatorArea, perimeter, and diagonal of a rectangle.Sphere CalculatorRadius, diameter, volume, and surface area of a sphere.Square CalculatorArea, perimeter, and diagonal of a square.Trapezoid CalculatorArea and perimeter of a trapezoid.Triangle CalculatorArea, perimeter, angles, and type of a triangle from three sides.
📐 Trigonometry 8
Angle ConverterConvert between degrees, radians, gradians, revolutions, arcminutes, and arcseconds.Inverse Trig CalculatorCompute arcsine, arccosine, and arctangent in degrees or radians.Law of Cosines CalculatorSolve a triangle from two sides + included angle, or three sides.Law of Sines CalculatorFind a missing side or angle in any triangle using the Law of Sines.Pythagorean Theorem CalculatorFind the missing side of a right triangle using a^2 + b^2 = c^2.Right Triangle CalculatorSolve a right triangle from any two of: leg a, leg b, hypotenuse c, or angle A.Trig CalculatorCalculate sin, cos, tan, csc, sec, cot for any angle.Unit Circle CalculatorFind (cos, sin) on the unit circle, all six trig functions, and quadrant.
📐 Specialty & Other Tools 8
Calendar CalculatorCount days until or since a target date.Day of the Week CalculatorFind what day of the week any date falls on.Discount CalculatorSee the sale price and how much you save.Interest Rate ConverterConvert between APR and APY for any compounding frequency.Sales Tax CalculatorAdd sales tax to any amount and see the total.Time Duration CalculatorCalculate the exact span between two dates.Tip CalculatorCalculate the tip and split the bill in one tap.Unit Price CalculatorCompare two package sizes and see which is cheaper per unit.
📐 Matrices & Vectors 8
Cross Product CalculatorCross product of two 3D vectors plus angle.Dot Product CalculatorDot product of two vectors plus angle between.Matrix Determinant CalculatorDeterminant of 2x2 and 3x3 matrices.Matrix Inverse CalculatorInverse of 2x2 and 3x3 matrices via adjugate method.Matrix Multiplication CalculatorMultiply two matrices A and B.Matrix Transpose CalculatorTranspose a matrix — rows become columns.Vector Magnitude CalculatorCompute vector magnitude and unit vector.Vector Projection CalculatorProject vector a onto vector b.
📐 Algebra 8
Distance Formula CalculatorFind the distance between two points using the distance formula.Linear Equation CalculatorSolve ax + b = c for x.Logarithm CalculatorCompute logarithms in any base.Midpoint CalculatorFind the midpoint between two points.Quadratic Formula CalculatorSolve any quadratic equation ax^2 + bx + c = 0 with real or complex roots.Slope CalculatorFind the slope, y-intercept, and equation of a line through two points.Slope-Intercept Form CalculatorFind the y = mx + b form of a line through two points.System of Equations CalculatorSolve a 2x2 system of linear equations.
📐 School / Homework 8
Long Division CalculatorDivide with quotient, remainder, and decimal result.Long Multiplication CalculatorMultiply with partial-product breakdown.Number to Words ConverterConvert a whole number into English words.Order of Operations CalculatorEvaluate an arithmetic expression using PEMDAS / BODMAS.Percent Decrease CalculatorCalculate the percent drop from an original value to a lower new value.Percent Increase CalculatorCalculate the percent change between two values.Roman Numeral ConverterConvert between decimal numbers and Roman numerals.Significant Figures CalculatorCount significant figures and round to a target precision.
📐 Education 7
Exam Score CalculatorTurn points earned out of a total into a percentage and letter grade, with bonus points and distance to an A.Final Grade CalculatorFind the score you need on your final exam to reach your target grade, plus your max possible grade and pass line.GPA CalculatorCalculate your grade point average from course grades and credit hours on the standard 4.0 scale.Grade CalculatorCompute your weighted overall grade and letter from category scores and weights, with weight remaining.Grade Curve CalculatorApply a flat, scale-to-top, or square-root curve to a score and see the adjusted grade and letter.Reading Time CalculatorEstimate how long text takes to read or read aloud from its word count, with page count and speed ranges.Study Time CalculatorPlan how many hours a day to study before an exam from your days available and total hours needed.
📐 Age & Date 6
Age CalculatorFind an exact age in years, months, and days from a date of birth, plus total days, weeks, and days to the next birthday.Business Days CalculatorCount the working days between two dates, excluding weekends, with calendar days, weekend days, and work weeks.Date CalculatorAdd or subtract days, weeks, months, or years from any date and get the result date, weekday, and distance from today.Date Difference CalculatorMeasure the time between two dates in years, months, and days, plus totals in days, weeks, and months.Days Between Dates CalculatorCount the days between two dates and see the span in weeks, months, hours, minutes, and decimal years.Due Date CalculatorEstimate a pregnancy due date from your last period, with weeks along and trimester. A general estimate, not medical advice.
📐 Developer 6
Base64 Encoder and DecoderEncode text to Base64 or decode it back, in your browser, with full UTF-8 support.Hex to RGB ConverterConvert colors between HEX, RGB, and HSL both ways, with a live swatch. Built for CSS and design work.JSON FormatterValidate, pretty-print, and minify JSON in your browser. Private, with helpful error messages.Lorem Ipsum GeneratorGenerate placeholder lorem ipsum text by paragraphs, sentences, or words for mockups and layouts.Password GeneratorGenerate strong random passwords in your browser with adjustable length and character types, plus a strength meter.Unix Timestamp ConverterConvert Unix timestamps to local, UTC, and ISO dates and back, with relative time. Runs in your browser.
📐 Work & Salary 6
Bonus CalculatorEstimate take-home on a bonus after withholding, as a flat amount or percent of salary. Estimate only, not tax advice.Commission CalculatorCalculate sales commission and total pay from your sales, rate, and base, with commission share of pay.Hourly Wage CalculatorTurn an hourly rate into yearly, monthly, weekly, and biweekly pay, with part-time and unpaid-week adjustments.Overtime CalculatorWork out total pay with overtime: regular pay, overtime pay at time and a half, and your effective hourly rate.Paycheck CalculatorEstimate take-home pay per paycheck and per year from gross pay and your own deduction rate. Estimate only, not tax advice.Salary CalculatorConvert pay between yearly, monthly, weekly, biweekly, and hourly. Gross figures for comparison, not tax advice.
📐 Science 6
Density CalculatorSolve density, mass, or volume from the density formula, with a float-or-sink check and kg/m3 output.Force Calculator (Physics)Solve Newton second law for force, mass, or acceleration, with pounds-force and g-force conversions.Kinetic Energy CalculatorSolve kinetic energy, mass, or velocity from the KE formula, with kJ and km/h conversions.Molarity CalculatorSolve molarity, moles, or volume from the concentration formula, with millimoles and milliliter conversions.Ohm Law CalculatorSolve Ohm law for voltage, current, or resistance and get electrical power. The core formula for basic electronics.pH CalculatorConvert between hydrogen ion concentration and pH, with pOH, hydroxide concentration, and acidic/basic classification.
📐 Basic 5
Basic CalculatorAdd, subtract, multiply, divide, raise to a power, or take a modulo.Decimal CalculatorConvert a decimal to a reduced fraction, mixed number or percent.Mixed Number CalculatorAdd, subtract, multiply or divide mixed numbers.Root CalculatorFind the nth root of any number.Scientific CalculatorApply scientific functions.
📐 Health & Fitness 5
BMI CalculatorEstimate body mass index from height and weight in US or metric units, with the healthy weight range for your height. A screening estimate, not medical advice.BMR CalculatorEstimate basal metabolic rate with the Mifflin-St Jeor equation, plus rough maintenance estimates by activity. Estimates only, not medical advice.Body Fat CalculatorEstimate body fat percentage with the US Navy tape method, plus fat and lean mass. A rough estimate, not medical advice.Heart Rate Zone CalculatorEstimate your max heart rate and five training zones from your age, with the Karvonen method if you add resting heart rate.Ideal Weight CalculatorSee a healthy weight range for your height plus Devine, Robinson, Miller, and Hamwi reference estimates. References, not a goal or medical advice.
📐 Environment 5
Carbon Footprint CalculatorEstimate your yearly CO2 emissions from driving, home energy, and flights, with a per-person figure and tree offset.Electricity Cost CalculatorWork out what any device costs to run per day, month, and year from its wattage, hours, and your rate.Solar Panel CalculatorEstimate solar system size, panel count, cost, and payback from your electricity use and local sun hours. A rough estimate, not a quote.Tree Offset CalculatorEstimate how many trees it would take to absorb a given amount of CO2 per year. A rough offset reference.Water Usage CalculatorEstimate household water use per day, week, and year from showers, flushes, and laundry, with your biggest use.
📐 Fun & Misc 5
Coin Flip CalculatorFlip a fair coin once or hundreds of times, with heads/tails tally, heads percentage, and the full sequence.Countdown CalculatorCount the days, weeks, and hours until any date, with the weekday it falls on and a business-day estimate.Dice RollerRoll any number of dice from d4 to d100 with a modifier, using fair browser randomness. Shows each die and the total.Random Number GeneratorGenerate random numbers in any range, with or without duplicates, using fair browser randomness. Great for lotteries and sampling.Random PickerPick random winners from a list of names or items for giveaways, raffles, and fair decisions. Runs in your browser.
📊 Number Theory 5
Factor CalculatorList all positive factors of a whole number.GCF CalculatorFind the greatest common factor of two or three whole numbers.LCM CalculatorFind the least common multiple of two or three whole numbers.Prime Factorization CalculatorBreak a whole number into its prime building blocks.Prime Number CalculatorCheck whether a whole number is prime.
📐 Complex Numbers 4
Complex Conjugate CalculatorConjugate of z = a + bi with key identities.Complex Modulus & Argument CalculatorModulus, argument, and polar form of a complex number.Complex Number CalculatorAdd, subtract, multiply, divide complex numbers; modulus and conjugate.Polar / Rectangular Form ConverterConvert complex numbers between rectangular and polar forms.
➗ Fractions & Ratios 4
Fraction CalculatorAdd, subtract, multiply, or divide two fractions and get the answer simplified, as a mixed number, and as a decimal.Fraction to Decimal ConverterConvert a decimal to a simplified fraction, or turn any fraction into a decimal and percentage.Proportion CalculatorSolve a proportion A : B = C : x for the missing value.Ratio Calculator (Simplifier)Reduce a ratio to its simplest whole-number form, with two or three terms.
📐 Travel 4
Packing List CalculatorGet a suggested clothing packing list by trip length, laundry access, climate, and trip type.Speed Distance Time CalculatorSolve for speed, distance, or time given the other two, in miles and mph, with km/h and minutes.Time Zone ConverterConvert a time between any two UTC offsets, with the time difference and day change. Supports half-hour zones.Travel Time CalculatorEstimate driving time and arrival from distance, average speed, breaks, and departure time, with a halfway point.
🔢 Arithmetic & Percentages 3
Average Calculator (Mean, Median, Mode)Paste a list of numbers and get the mean, median, mode, range, sum, and count instantly.Percentage CalculatorThree percentage tools in one: find a percentage of a number, work out what percent one number is of another, and measure a percentage increase or decrease.Rounding CalculatorRound any number to a set number of decimal places, or to the nearest 10, 100, or 1000.
🧮 Powers & Roots 3
Exponent Calculator (Power)Raise any number to any power, including negative and fractional exponents.Scientific Notation ConverterConvert numbers to scientific notation and back, with the coefficient and exponent shown.Square Root CalculatorFind the square root, cube root, or any nth root of a number.
📐 Shopping 2
📊 Number Theory & Stats 1
More calculators on Formula Factory
These categories have their own full hubs — jump straight in.
Math →Basic, scientific, fractions, percentages, algebra, geometry, and moreCooking →Recipe scaling, unit conversions, baking percentages, and kitchen mathHome & Living →Paint, flooring, tile, roofing, fencing, and project estimatorsConversion →Length, weight, temperature, volume, pressure, and data converters
What you can calculate here
This hub blends practical everyday tools with core math. Everyday tools handle tips, discounts, sales tax, time and date differences, unit conversions, and age. Math tools cover percentages, fractions, ratios, averages, and rounding, plus geometry for area, perimeter, and volume and trigonometry for sides and angles. Whether you are splitting a bill or checking homework, the right tool is a click away.
Who these calculators are for
Shoppers work out discounts, tax, and tips in seconds. Students check homework and follow the method. Parents and tutors use the diagrams to explain a concept. Anyone planning around dates, budgets, or measurements gets a quick, dependable answer without opening a spreadsheet.
Getting accurate results
A few small checks keep the answers right:
- Check whether a percentage is of the original or the discounted amount. The tools label which they use.
- For time and date math, confirm the start and end points and whether the final day is included.
- With geometry, make sure you have the measurement the tool asks for, such as radius versus diameter.
- Results are rounded for readability while full precision is kept internally.
Frequently asked questions
Are these calculators free?
Yes. Every everyday and math calculator here is free, with no account and no usage limit.
Does this cover both everyday tasks and school math?
Yes, both. Tips, discounts, and date math sit alongside percentages, geometry, and trigonometry.
How accurate are the results?
They use standard formulas and are accurate for the values you enter. Any rounding is for display only.
Will they work on my phone?
Yes. Every tool is responsive and works the same on phone, tablet, and desktop.
Which calculator should I start with?
Pick your task: a percentage, a tip, a date gap, or a shape. Each tool links to related ones.
Do you store the numbers I enter?
No. Everything is calculated in your browser, and your inputs are not saved or sent anywhere.