38
Construction
Concrete, framing, roofing, decking, fencing, flooring, landscaping and paint calculators for builders and DIYers.
All construction →Calculators that make sense.
240 free calculators for building, money, health, cooking, maths and time. Clear inputs, straight answers, and the formula shown so you can check the working.
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24-Hour Clock ConverterConvert 24-hour (military) time to 12-hour and back.50/30/20 Budget CalculatorSplit take-home pay into needs, wants and savings.Acceleration CalculatorAcceleration from velocity change and time.Acreage CalculatorAcres and hectares from plot dimensions.Acres to Hectares ConverterConvert acres to hectares.Add or Subtract Days From a DateFind the date a number of days, weeks or months away.Age CalculatorExact age in years, months and days.Amortization Schedule CalculatorFull loan amortization table by year.Amps to Watts CalculatorPower from current and voltage (AC and DC).Angle ConverterConvert between 7 angle units.APR to APY CalculatorConvert APR to APY and back.Aquarium Volume CalculatorGallons and weight of a fish tank.Arc Length CalculatorArc length, chord and sector area.Area CalculatorArea of rectangles, triangles, circles and more.Area ConverterConvert between 10 area units.Aspect Ratio CalculatorResize images and video keeping proportions.Average CalculatorMean, median, mode, range and standard deviation.Baluster CalculatorNumber of balusters and spacing for a railing.Battery Life CalculatorRuntime from battery capacity and load.Binary, Hex & Number Base ConverterConvert between binary, octal, decimal and hex.BMI CalculatorBody mass index with healthy weight range.Board Foot CalculatorBoard feet of lumber and cost.Body Fat CalculatorBody fat percentage using the US Navy method.Body Surface Area CalculatorBSA using the Mosteller formula.Box Volume Calculator (L×W×H)Volume of a box in cubic feet, inches and litres.Break-Even CalculatorUnits and revenue needed to break even.Brick CalculatorNumber of bricks for a wall.Butter ConverterSticks, cups, tablespoons and grams of butter.CAGR CalculatorCompound annual growth rate.Cake Pan Size ConverterScale a recipe to a different tin size.Calorie Calculator (BMR & TDEE)Daily calories to maintain, lose or gain weight.Calories Burned CalculatorCalories burned for 16 activities.Car Finance CalculatorMonthly car finance payments (hire purchase).Carburetor CFM CalculatorCarburetor size for an engine.Cat Age CalculatorYour cat’s age in human years.CBM CalculatorCubic metres and cubic feet of cartons.Celsius to Fahrenheit ConverterConvert degrees Celsius to degrees Fahrenheit instantly.Centimetres to Inches ConverterConvert centimetres to inches instantly.Check Square CalculatorDiagonal measurement to square a corner or frame.Circle CalculatorArea, circumference and diameter of a circle.Coffee Ratio CalculatorCoffee grounds and water for any brew.Commission CalculatorSales commission and total pay.Compound Interest CalculatorGrow savings with compounding and monthly deposits.Compression Ratio CalculatorStatic compression ratio of an engine.Concrete CalculatorConcrete volume and bags for a slab, in metric or imperial.Concrete Column & Footing CalculatorConcrete for round columns (Sonotubes) and footings.Cooking Measurement ConverterCups, tablespoons, teaspoons, ml and fl oz.Credit Card Payoff CalculatorMonths to pay off a card and interest paid.Cubic Feet CalculatorVolume in cubic feet, with cost.Cubic Metre CalculatorVolume in m³ and litres, with cost.Cubic Yards CalculatorVolume in cubic yards from dimensions.Cups to Grams ConverterConvert cups to grams for flour, sugar, butter and more.Data Storage ConverterConvert between 10 data storage units.Day of the Week CalculatorWhat day of the week any date falls on.Days Between Dates CalculatorDays, weeks and business days between two dates.Days Until CalculatorCountdown in days to any date.Debt-to-Income Ratio CalculatorDTI ratio lenders use for mortgages.Decimal Hours ConverterConvert decimal hours to hours and minutes.Decimal to Fraction CalculatorConvert decimals to simplified fractions.Deck & Fence Stain CalculatorGallons of stain for a deck or fence.Deck Board CalculatorNumber of deck boards and screws.Degrees Minutes Seconds ConverterConvert DMS to decimal degrees and back.Density CalculatorSolve for density, mass or volume.Dilution Calculator (C1V1 = C2V2)Stock volume needed for a dilution.Dimensional Weight CalculatorDIM weight and billable weight for parcels.Dog Age CalculatorYour dog’s age in human years.Dog Calorie CalculatorDaily calories for your dog.Dog Chocolate Toxicity CalculatorHow dangerous the chocolate your dog ate is.Dog Pregnancy CalculatorWhelping due date for your dog.Drywall CalculatorSheets of drywall for walls and ceiling.Electricity Cost CalculatorRunning cost of any appliance per day, month and year.Energy ConverterConvert between 11 energy units.Engine Displacement CalculatorDisplacement from bore, stroke and cylinders.EV Charging Cost CalculatorCost to charge an electric car.EV Charging Time CalculatorHow long an electric car takes to charge.Exponent CalculatorRaise a number to any power.Fahrenheit to Celsius ConverterConvert degrees Fahrenheit to degrees Celsius instantly.Feet and Inches CalculatorAdd or subtract measurements in feet and inches.Feet to Metres ConverterConvert feet to metres instantly.Fence CalculatorPosts, rails and pickets for a fence.Final Exam Grade CalculatorScore needed on the final to hit a target.Flooring CalculatorBoxes of laminate, vinyl or wood flooring.Force Calculator (F = ma)Newton’s second law.Force ConverterConvert between 6 force units.Fraction CalculatorAdd, subtract, multiply and divide fractions.Frequency ConverterConvert between 6 frequency units.Fuel Economy (MPG) CalculatorYour car’s real MPG and cost per mile.Fuel Economy ConverterConvert MPG, UK MPG, L/100 km and km/L.Future Value CalculatorFuture value of a lump sum and regular payments.Gallons to Litres ConverterConvert US gallons to litres.GCF and LCM CalculatorGreatest common factor and least common multiple.Gear Ratio & Speed CalculatorVehicle speed from RPM, gearing and tyre size.GPA CalculatorGrade point average from letter grades and credits.Grams to Moles CalculatorConvert grams to moles and molecules.Grams to Ounces ConverterConvert grams to ounces.Grass Seed CalculatorPounds of grass seed for new or overseeded lawns.Gravel, Sand & Soil CalculatorTonnes and volume of gravel, sand or soil.Half-Life CalculatorRemaining quantity after radioactive decay.Ham Cooking Time CalculatorRoasting time for a ham by weight and type.Height Converter (cm ↔ feet & inches)Convert height between cm and feet/inches.Horsepower CalculatorHorsepower from torque and RPM.Horsepower to Amps CalculatorMotor current from horsepower.Hourly to Salary CalculatorAnnual salary from an hourly wage.Hours CalculatorHours worked between two times, minus breaks.Ideal Gas Law CalculatorSolve PV = nRT for any variable.Ideal Weight CalculatorIdeal body weight by four published formulas.Inches to Centimetres ConverterConvert inches to centimetres instantly.Inflation CalculatorFuture cost or past value at an inflation rate.Journey Fuel Cost CalculatorFuel cost for a journey or road trip.Kilograms to Pounds ConverterConvert kilograms to pounds instantly.Kilometres to Miles ConverterConvert kilometres to miles.Kinetic Energy CalculatorKinetic energy from mass and velocity.kVA to Amps CalculatorCurrent from kVA for single and three phase.Lean Body Mass CalculatorLean body mass with the Boer formula.Length ConverterConvert between mm, cm, m, km, inches, feet, yards and miles.Linear Metres & Linear Feet CalculatorTotal length of pieces and cost per metre or foot.Litres to Gallons ConverterConvert litres to US gallons.Loan & Mortgage Payment CalculatorMonthly payment, total interest and total cost of a loan.Loan Payoff CalculatorHow extra payments shorten a loan.Logarithm CalculatorLog base 10, natural log and any base.Long Division CalculatorQuotient and remainder with decimal answer.Macro CalculatorDaily protein, carbs and fat in grams.Markup CalculatorSelling price from cost and markup or margin.Metres to Feet ConverterConvert metres to feet.Miles to Kilometres ConverterConvert miles to kilometres instantly.mL to Fluid Ounces ConverterConvert millilitres to US fluid ounces.Molar Mass CalculatorMolar mass of any chemical formula.Molarity CalculatorMolarity, mass or volume of a solution.Momentum CalculatorMomentum from mass and velocity.Mortgage CalculatorMonthly mortgage payments, repayment or interest-only.MPH to km/h ConverterConvert miles per hour to kilometres per hour.Mulch CalculatorVolume and bags of mulch or bark for a bed.Multiple Room Area CalculatorTotal floor area of several rooms.Net Worth CalculatorAssets minus liabilities.Ohm's Law CalculatorVoltage, current, resistance and power from any two values.One-Rep Max CalculatorEstimate your 1RM from any set.Online CalculatorA simple calculator — type any sum.Ounces to Grams ConverterConvert ounces to grams.Oven Temperature Converter°F, °C, fan oven and gas mark.Oven to Air Fryer ConverterConvert oven recipes for an air fryer.Overtime Pay CalculatorPay including time-and-a-half or double time.Ovulation CalculatorFertile window and next ovulation date.Paint CalculatorLitres or gallons of paint for a room.Paver CalculatorNumber of pavers for a patio or path.Pay Raise CalculatorNew salary after a percentage raise.Percent Error CalculatorPercent error between measured and true values.Percent Off CalculatorSale price and savings after a discount.Percent Yield CalculatorPercent yield of a chemical reaction.Percentage CalculatorPercent of a number, percent of total and percent change.Percentage Difference CalculatorPercent difference between two values.Perimeter CalculatorPerimeter of rectangles, circles and triangles.Permutation & Combination CalculatornPr, nCr and factorials.pH CalculatorpH, pOH and ion concentrations.Pizza Size CalculatorCompare pizza sizes and price per square inch.Pool Volume CalculatorGallons and litres of water in a pool.Post Hole Concrete CalculatorConcrete bags to set fence or deck posts.Potential Energy CalculatorGravitational potential energy mgh.Pounds to Kilograms ConverterConvert pounds to kilograms instantly.Power ConverterConvert between 7 power units.PPI / Pixel Density CalculatorPixels per inch of a screen.PPM ConverterConvert ppm, ppb, percent and mg/L.Pregnancy Due Date CalculatorEstimated due date from the last period.Present Value CalculatorWhat a future sum is worth today.Pressure ConverterConvert between 9 pressure units.Prime Factorization CalculatorPrime factors and whether a number is prime.Profit Margin CalculatorGross margin, markup and profit.Projector Throw Distance CalculatorDistance from projector to screen.Protein Intake CalculatorDaily protein needs by weight and goal.Pythagorean Theorem CalculatorHypotenuse and angles of a right triangle.Quadratic Equation SolverSolve ax² + bx + c = 0, including complex roots.Rafter Length CalculatorRafter length from span, pitch and overhang.Random Number GeneratorRandom whole numbers in any range.Ratio CalculatorSimplify ratios and solve A:B = C:D.Recipe ScalerScale every ingredient to a new number of servings.Regular Polygon CalculatorArea, angles and radius of a regular polygon.Resistor Colour Code CalculatorResistance from 4-band colour codes.Retaining Wall CalculatorBlocks and caps for a retaining wall.Rice CalculatorUncooked rice and water for cooked portions.ROI CalculatorReturn on investment and annualised return.Roman Numeral ConverterConvert numbers to Roman numerals and back.Roof Pitch CalculatorRoof pitch, angle and slope from rise and run.Roof Sheathing CalculatorPlywood or OSB sheets for a roof deck.Roofing Shingles CalculatorRoofing squares, shingle bundles and drip edge.Rounding CalculatorRound to decimals, tens, hundreds or significant figures.Rule of 72 CalculatorHow long money takes to double.Running Pace CalculatorPace per mile and kilometre from distance and time.Salary to Hourly CalculatorTurn an annual salary into hourly, weekly and monthly pay.Savings Goal CalculatorMonthly saving needed to hit a target.Scale CalculatorConvert real sizes to scale drawings and models.Scientific Notation ConverterConvert numbers to and from scientific notation.Screen Size CalculatorWidth and height from diagonal and aspect ratio.Series & Parallel Resistor CalculatorTotal resistance of resistors in series or parallel.Simple Interest CalculatorInterest on a principal at a flat rate.Sleep CalculatorBest bedtimes based on 90-minute sleep cycles.Slope CalculatorSlope, line equation and distance from two points.Sod CalculatorPieces, pallets and rolls of sod for a lawn.Speed ConverterConvert between 6 speed units.Speed, Distance & Time CalculatorSolve for speed, distance or time.Speedometer Error CalculatorTrue speed after changing tyre size.Square Feet to Square Metres ConverterConvert square feet to square metres.Square Footage CalculatorArea in square feet for any shape, with cost.Square Metre CalculatorArea in m² for any shape, with cost.Square Root & Nth Root CalculatorSquare, cube and nth roots.Stair CalculatorRiser height, step count and stringer length.Steps to Miles CalculatorConvert steps to miles, km and calories.Stone and Pounds to Kilograms ConverterConvert stone and pounds to kg and back.Surface Area CalculatorSurface area of 3D shapes.Tank Volume CalculatorLitres and gallons in a rectangular or cylindrical tank.Target Heart Rate CalculatorHeart rate training zones by age.Test Score CalculatorPercentage and grade from marks scored.Tile CalculatorHow many tiles you need for a floor or wall.Time CalculatorAdd or subtract hours, minutes and seconds.Time Unit ConverterConvert between 8 time units.Time Zone ConverterConvert a time between world time zones.Tip CalculatorTip amount and bill split between people.Torque ConverterConvert between 4 torque units.Triangle CalculatorAngles, area and perimeter from three sides.Trigonometry CalculatorSin, cos, tan and their inverses.Turkey Size CalculatorTurkey size, thawing and roasting time for your guests.TV Size & Viewing Distance CalculatorBest TV size for your seating distance.Tyre Size CalculatorTyre diameter, width and revolutions from a size code.Tyre Size Comparison CalculatorCompare two tyre sizes and speedometer error.Unit Price CalculatorCompare two products to find the better deal.Unix Timestamp ConverterConvert epoch time to a date and back.VAT CalculatorAdd or remove VAT from a price.Voltage Drop CalculatorVoltage drop along a cable run.Volume CalculatorVolume of cubes, cylinders, spheres, cones and more.Volume ConverterConvert between 15 volume units.Waist-to-Height Ratio CalculatorWaist-to-height and waist-to-hip ratios.Wallpaper CalculatorRolls of wallpaper needed for a room.Water Intake CalculatorHow much water to drink per day.Water Weight CalculatorWeight of a volume of water.Watts to Amps CalculatorCurrent draw from power and voltage (AC and DC).Wavelength & Frequency CalculatorConvert between wavelength and frequency.Weekly Timesheet CalculatorTotal weekly hours and pay from daily times.Weight & Mass ConverterConvert between 9 weight units.Weighted Grade CalculatorCourse grade from weighted assignments.Work & Power CalculatorWork done and power from force, distance and time.Z-Score CalculatorZ-score and percentile from mean and SD.Zone 2 Heart Rate CalculatorYour Zone 2 training heart rate range.
Most popular
Online CalculatorA simple calculator — type any sum.Percentage CalculatorPercent of a number, percent of total and percent change.VAT CalculatorAdd or remove VAT from a price.Square Metre CalculatorArea in m² for any shape, with cost.Concrete CalculatorConcrete volume and bags for a slab, in metric or imperial.Paint CalculatorLitres or gallons of paint for a room.Mortgage CalculatorMonthly mortgage payments, repayment or interest-only.BMI CalculatorBody mass index with healthy weight range.Stone and Pounds to Kilograms ConverterConvert stone and pounds to kg and back.Age CalculatorExact age in years, months and days.Days Until CalculatorCountdown in days to any date.Fuel Economy (MPG) CalculatorYour car’s real MPG and cost per mile.
Browse by category
All 240 calculators →34
Conversion
Fast, exact converters for length, area, volume, weight, temperature, speed, pressure, energy and more.
- Length Converter
- Inches to Centimetres Converter
- Centimetres to Inches Converter
- Feet to Metres Converter
- Pounds to Kilograms Converter
31
Financial
Mortgages, loans, interest, investing, business and personal finance calculators.
All financial →19
Health & Fitness
BMI, calories, macros, heart rate zones, body composition, running and exercise calculators.
All health & fitness →38
Maths
Percentages, fractions, algebra, geometry, trigonometry, statistics and grade calculators.
All maths →19
Science
Physics and chemistry calculators: motion, energy, gas laws, molar mass, molarity and pH.
All science →13
Automotive
Fuel economy, trip cost, EV charging, tyre size, gearing and engine calculators.
All automotive →12
Time & Date
Age, date differences, time zones, timesheets and time conversions.
All time & date →12
Cooking
Kitchen conversions, recipe scaling, oven temperatures and cooking times.
- Cups to Grams Converter
- Recipe Scaler
- Turkey Size
- Oven Temperature Converter
- Oven to Air Fryer Converter
10
Electrical
Ohm's law, power conversions, voltage drop, resistors, batteries and energy costs.
All electrical →6
Pets
Dog and cat age, calorie needs, pregnancy dates and aquarium calculators.
All pets →5
TV & Video
TV size, viewing distance, aspect ratio, pixel density and projector calculators.
All tv & video →3
Shipping
CBM, box volume and dimensional weight calculators for shipping and freight.
All shipping →Why Sensible Calculators?
No vague guesses
We only ask for what the answer needs, and never hide rough assumptions inside a result.
Working shown
Every calculator explains the formula it uses, so you can check the maths for yourself.
UK first
Metres and litres, pounds sterling, 20% VAT, stone and UK mpg — with imperial when you want it.
Private by design
Calculations happen on your device. Nothing you type is sent to us.
How it works
- Find your calculatorSearch, or browse by category.
- Enter your numbersPick the units you measured in.
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Frequently asked questions
Are the calculators really free?
Yes. Every calculator on Sensible Calculators is free to use with no sign-up, no limits and no paywall. The site is supported by advertising.
Do you store the numbers I enter?
No. Every calculation runs in your own browser, so the values you type never leave your device.
Do the calculators use UK units?
Yes. Calculators default to metric units, pounds sterling and UK conventions such as 20% VAT, stone for body weight and UK mpg, with imperial and US options where they are useful.
How accurate are the results?
Each calculator uses a published, standard formula, which is shown on the page so you can check the working. Some results, such as calorie needs or roasting times, are estimates — the page always says so.
Can I suggest a new calculator?
Please do — get in touch through the contact page and tell us what you need to work out.
Can’t find what you need?
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