Calculator index
All calculators
Browse every live calculator by category, or search for the question you need to answer.
Financial Calculators
Plan pay, borrowing, repayments, savings and everyday money decisions with transparent formulas and clear assumptions.
FinanceTake Home PayEstimate annual, monthly and weekly take-home pay for the 2026 to 2027 UK tax year.FinanceMortgageEstimate monthly mortgage payments, total interest and loan-to-value from property price, deposit, rate and term.FinanceLoanCalculate monthly payments, total repayment and interest cost for a fixed-rate personal loan.FinanceCurrencyConvert an amount using a manual exchange rate and compare the effect of fees or card markups.FinanceCompound InterestProject savings growth with starting balance, regular deposits, annual rate and compounding frequency.FinanceVATAdd or remove VAT from a price and see the net, VAT and gross amounts.FinanceSavings GoalWork out the monthly saving needed to reach a goal by a target date.FinanceCard PayoffEstimate how long it could take to clear a credit card balance with a fixed monthly payment.FinanceDebt SnowballCompare a debt snowball payoff plan across three balances with an extra monthly payment.FinanceAPREstimate APR from amount borrowed, fees, monthly payment and loan term.FinanceInflationEstimate how inflation changes future cost and purchasing power using a chosen annual rate.FinanceRetirementProject retirement savings from current age, savings, monthly contributions and expected return.FinanceBudget PlannerSplit monthly income across bills, essentials, debt, saving and flexible spending.
Health and Fitness Calculators
Estimate calorie needs, body metrics, training targets and nutrition splits with careful health disclaimers and plain formula notes.
HealthCaloriesEstimate daily maintenance calories using the Mifflin-St Jeor equation and an activity multiplier.HealthMacrosSplit daily calories into protein, fat and carbohydrate targets using body weight and preferred fat percentage.HealthBMICalculate adult body mass index from height and weight, with standard category ranges.HealthPaceCalculate running pace, finish time or distance from any two values.HealthBody FatEstimate body fat percentage from circumference measurements using the US Navy method.HealthBMREstimate basal metabolic rate using the Mifflin-St Jeor equation.HealthOne Rep MaxEstimate one rep max and training percentages from weight lifted and reps completed.HealthHeart ZonesEstimate maximum heart rate and training zones from age and resting heart rate.HealthWater IntakeEstimate daily fluid needs from body weight, activity and warm conditions.HealthDue DateEstimate a pregnancy due date from the first day of the last menstrual period.HealthWaist Hip RatioCalculate waist-to-hip ratio from body measurements.
Maths Calculators
Solve common arithmetic, algebra, geometry and statistics tasks quickly, with enough working to help users understand the result.
MathsPercentageCalculate percentages, percentage change and reverse percentages for discounts, marks and comparisons.MathsScientificEvaluate arithmetic, powers, roots and common trigonometric functions in a clean browser calculator.MathsFractionsAdd, subtract, multiply or divide two fractions and reduce the result.MathsRatioSimplify a ratio, compare parts and scale a ratio to a chosen total.MathsQuadraticSolve ax squared plus bx plus c equals zero and show the discriminant.MathsStandard DeviationCalculate mean, variance and standard deviation from a list of numbers.MathsProbabilityCalculate single-event probability, odds and the chance of at least one success across repeated trials.MathsAreaCalculate the area of a rectangle, triangle, circle or trapezium.MathsVolumeCalculate volume for a cuboid, cylinder, sphere or cone.MathsPrime FactorsBreak a whole number into its prime factors.MathsRandom NumberGenerate repeatable random-style whole numbers from a range and seed.
Science and Engineering Calculators
Practical tools for physics, chemistry, units and technical formulas, designed for quick checking and repeat use.
ScienceUnit ConversionConvert common length, weight, temperature and volume units with instant results.ScienceOhm's LawCalculate voltage, current, resistance or power from any two known electrical values.ScienceSpeed Distance TimeCalculate speed, distance or time when you know the other two values.ScienceDensityCalculate density, mass or volume when you know the other two values.ScienceForceCalculate force from mass and acceleration using Newton's second law.SciencePressureCalculate pressure from force and area.ScienceMolarityCalculate molarity from moles of solute and solution volume.ScienceDilutionCalculate stock solution volume using C1V1 equals C2V2.SciencepHConvert hydrogen ion concentration to pH, or pH to hydrogen ion concentration.ScienceEnergyCalculate kinetic, electrical or heat energy using common formulas.
Fashion and Size Calculators
Compare size systems, body measurements and fit notes across shoes, dresses, jeans, rings and brand-specific charts.
SizesShoe SizesCompare UK, US men's, US women's, EU and Mondopoint shoe sizes with practical fit notes.SizesDress SizesEstimate UK, US and EU dress sizes from bust, waist and hip measurements.SizesRing SizeEstimate UK and US ring size from inner diameter or finger circumference.SizesBrand Shoe FitCompare a usual shoe size with broad fit notes for popular footwear brands.SizesDress ComparisonConvert a women's dress size between UK, US, EU, French and Italian systems.SizesJeans SizeEstimate jeans waist and leg size from body measurements.SizesBra SizeEstimate UK bra band and cup size from underbust and bust measurements.SizesKids ShoesEstimate children's shoe size from foot length and growth room.SizesHat SizeEstimate hat size from head circumference.SizesClothing SizesConvert broad women's, men's and children's clothing sizes across common systems.
Home and DIY Calculators
Estimate paint, flooring, concrete, room measurements and project quantities before buying materials.
HomePaintEstimate litres of paint needed from wall area, coats and paint coverage.HomeTilesEstimate how many tiles are needed for a floor or wall, including waste.HomeConcreteEstimate concrete volume for slabs, footings and simple rectangular pours.HomeRoof PitchCalculate roof pitch, angle and slope factor from rise and run.HomeBTUEstimate room heating output in BTU per hour from room size and insulation.HomeMoving BoxesEstimate how many boxes you may need for a house move.
Time and Date Calculators
Calculate age, date differences, working days, hours, time zones and countdowns.
TimeAgeCalculate exact age in years, months and days from a date of birth.TimeDate DifferenceCount the days, weeks, months and years between two dates.TimeBusiness DaysCount weekdays between two dates and optionally exclude UK bank holidays entered manually.TimeHoursCalculate hours between two times with an optional break.TimeTime ZoneConvert a date and time between two UTC offsets.TimeCountdownCount days, weeks and approximate months until a future date.
Business Calculators
Model margins, returns, break-even points, advertising maths and small business cash flow questions.
BusinessProfit MarginCalculate gross profit, profit margin and markup from cost and selling price.BusinessROICalculate return on investment from cost, return and optional time period.BusinessBreak-EvenCalculate the units and revenue needed to cover fixed and variable costs.BusinessMarkupAdd a markup to cost and compare markup percentage with profit margin.BusinessConversion RateCalculate conversion rate from visitors, leads, orders or other actions.BusinessCPMCalculate cost per thousand impressions, total cost or impressions for advertising campaigns.BusinessCash RunwayEstimate how many months a business can operate from cash balance, revenue and expenses.BusinessCPCCalculate cost per click, cost per conversion and conversion rate for paid campaigns.BusinessLifetime ValueEstimate customer lifetime value from order value, purchase frequency, lifespan, margin and acquisition cost.