Calculators

Size an air conditioner for a room, with the adjustments for sun, ceiling height, occupants and kitchens.

Find an exact age in years, months and days from a date of birth — plus the next birthday countdown.

The exact age gap between two people in years, months, days and weeks.

Resize without distortion, identify the ratio of any size, or fit an image inside a box.

Your attendance so far, how many classes you must attend in a row to reach the requirement, and how many you can still miss.

Find the mean, median, mode and range of a list of numbers, pasted in any format.

Convert a bread recipe between weights and baker's percentages, with hydration worked out.

How long a battery lasts at a given draw, with realistic usable capacity.

Probability of exactly, at most or at least k successes in n independent trials.

Calculate Body Mass Index in metric or imperial units, with the WHO category and healthy weight range.

Basal metabolic rate from three equations at once, with the spread shown.

Board feet from thickness, width and length, with waste and cost worked out.

Estimate body fat percentage from tape measurements or from height and weight.

Delay and reverb times in milliseconds for every note value at a given tempo.

Find the sales volume that covers your fixed costs, and what a target profit needs.

Find the compound annual growth rate between two values, and the absolute return alongside it.

Estimate your BMR and daily calorie needs with a choice of recognised formulas.

Decode the three-digit marking on a capacitor into pF, nF and µF at once.

Auto loan payment including sales tax, trade-in, fees and negative equity.

Work out a credit-weighted CGPA across any number of subjects, with optional percentage conversion.

Balances a reaction into the smallest whole-number coefficients, and recounts every atom.

Project growth with any compounding frequency, with optional regular monthly contributions.

Static compression ratio from bore, stroke, chamber, gasket, deck and piston volumes — plus the dynamic ratio a camshaft actually delivers.

Concrete volume for a slab, footing, wall or column, with bags or a cement, sand and aggregate split.

Build a confidence interval for a mean or a proportion, with the margin of error.

Add or subtract days, weeks, months and years, or count down to a date.

Count the days, weeks and months between two dates — with or without weekends.

Compare avalanche and snowball strategies across all your debts at once.

Convert between ratios and decibels, and between dBm, dBW, dBV and dBu.

Near and far focus limits, hyperfocal distance and the diffraction ceiling for a given format, lens and aperture.

Dew point, wet bulb and absolute humidity from a temperature and a humidity reading, with the temperature a surface starts sweating at.

Solve C₁V₁ = C₂V₂ for stock volume, final volume or either concentration.

Work out volumetric weight and which of it or actual weight a courier will bill.

Find the sale price and the amount saved, or work backwards to the discount percentage.

How long a file takes to download, with bits and bytes kept straight.

Estimate a monthly bill from appliance usage, on flat or slab tariffs.

Work out the monthly instalment on a loan, with total interest and a full amortisation schedule.

Displacement from bore, stroke and cylinder count, with the bore/stroke ratio and compression.

Project an Employees' Provident Fund balance from basic pay, contributions and years of service.

Estimates how long an electric car takes to charge, what the electricity costs and how much range it buys.

Work out what a fixed deposit matures to, with any compounding frequency and the effective yield.

Apparent temperature from the published heat index and wind chill formulas, with the dew point.

Posts, rails, pickets and concrete for a run of fence, with gates taken out of the length.

Find the score you need on the final exam to reach the overall grade you want.

Add, subtract, multiply and divide fractions and mixed numbers, with exact results.

Works back from the income you want to the hourly rate you have to charge, after unpaid hours, expenses and tax.

Work out what a trip costs in fuel, in km/l, mpg or l/100km, split between passengers.

Gear ratio, output speed and torque for a train of up to four stages.

Estimate gratuity under the Payment of Gratuity Act from last drawn salary and years of service.

Add or remove GST at any rate, with the CGST and SGST split shown separately.

Solves exponential decay for the amount left, the time taken, or the half-life itself.

Five training zones from your age or measured maximum, by percentage or Karvonen.

Power from torque and RPM, or either from the other two, in hp, kW and PS — with a wheel-to-crank estimate.

Weekly timesheet — clock in and out, deduct breaks, split overtime and pay.

Find the exempt portion of your house rent allowance, and how much of it stays taxable.

Solves PV = nRT for pressure, volume, moles or temperature, in whatever units you have.

Four clinical formulas plus the healthy BMI range, with the disagreement shown.

Compare the old and new regimes on your income, with slabs, rebate, surcharge and cess shown.

See what an amount will cost later, and what today's money will still be able to buy.

Find the ISO week for a date, or the dates in a given week, with the week-year.

Resonant frequency of an LC circuit, or the inductor or capacitor to reach one.

Find the highest common factor and lowest common multiple of two or more numbers, with the factorisation shown.

Work out the series resistor an LED needs, and what to actually buy for it.

Fit a least-squares line to your data points, with R², significance and prediction.

Solve for payment, loan amount or tenure, and see total cost with a repayment schedule.

Estimate how much you could borrow from your income, obligations, rate and tenure.

See what a lump-sum prepayment saves, comparing a shorter tenure against a lower EMI.

Convert lamp output to illuminance over an area, or find the lumens a space needs.

Project what a single investment grows to, with the year-by-year path shown.

Determinant, inverse, transpose, product, sum and scalar multiple for matrices up to 6×6.

Works out what an hour in the room costs, from the number of people in it and what their time is worth.

Weight of bar, tube, plate and angle in any alloy, per piece, per metre and for the whole order.

Measure real fuel efficiency from distance and fuel used — km/l, mpg and l/100km.

Work out the mass to weigh, the concentration you made, or the volume a mass will give.

The Moon's phase, illuminated percentage and age for any date, with the next four phase dates.

Full monthly housing cost — principal, interest, tax, insurance, HOA and PMI.

Astable frequency and duty cycle, monostable pulse width, or the resistor pair that hits a frequency you name.

Add up everything you own and owe to get a single financial position.

Frequency of any musical note, or the nearest note to any frequency, at your tuning.

Project a National Pension System corpus, the lump sum you may take at exit, and the pension the rest buys.

The nth term and the sum of an arithmetic or geometric sequence, or identify one from its terms.

Enter any two of voltage, current, resistance and power to get the other two.

Estimate a one-rep max from a set, across six formulas, with the training percentages.

Inverting and non-inverting gain from the feedback resistors, with output clipping, bandwidth and the slew rate limit.

How much paint a room needs, from its dimensions, the openings, the coats and the spread rate.

Combine up to ten resistors in parallel or series into one equivalent value.

Five percentage calculations in one place — including percentage change and reverse percentages.

Count arrangements and selections — nPr, nCr, with or without repetition — with exact results and the formula shown.

pH, pOH and ion concentrations for strong and weak acids and bases, with pKw that moves with temperature.

Project a Public Provident Fund balance over 15 years or more, with a year-by-year table.

Find margin and markup from cost and price, or price for a target of either.

Range, peak height, flight time and impact for a projectile launched at a speed and angle.

Belt length from two pulleys and a centre distance, or the centre distance from a belt you already have, with wrap angles.

Solve ax² + bx + c = 0 with roots, discriminant, vertex and factored form.

Ramp run, gradient and landings for a given rise, against ADA or UK Part M limits.

Simplify a ratio, share an amount in proportion, or solve for a missing term.

Time constant, charge curve and filter corner frequency for a resistor and capacitor.

Find the maturity value of a recurring deposit from the monthly instalment, rate and term.

Rescale a whole ingredient list by servings or a multiplier, keeping quantities as kitchen fractions.

Compares renting and buying as net worth over time, with the renter investing the deposit and the monthly difference.

Read a resistor's value from its bands, or find the bands for a value you need.

Compare the corpus you are on track to build against the one your retirement actually needs.

Work out return on investment, with an annualised figure when you supply a period.

Convert between rise-in-12, degrees and percent, and get rafter lengths and true roof area.

Solve pace, time or distance, with a split table and equivalent times at other race distances.

Break an annual CTC into its components and estimate the monthly take-home pay.

Convert pay between hourly, daily, weekly, monthly and annual — both directions.

Add or remove US sales tax with stacked state, county, city and district rates.

How many people to survey for a given margin of error and confidence level.

What you will have, what you must save, or how long it takes to reach a goal.

A full scientific calculator with trigonometry, logarithms, powers and memory keys.

Pixel density, panel size and viewing distance from a resolution and a diagonal.

Count the significant figures in a number, round to a given number of them, or propagate them correctly through a calculation.

Calculate simple interest and maturity value from principal, rate and time.

Project what a monthly investment could grow to, with an optional annual step-up.

Bedtimes or wake-up times that land between sleep cycles, with the time it takes you to fall asleep counted in.

Slope, angle, distance, midpoint and the equation of the line through two points.

Size a solar array from your electricity use: panel count, kWp, roof area and annual generation.

Solves Q = mcΔT for heat, mass, specific heat or temperature change, and warns when a phase change breaks it.

Work out floor or plot area from measurements, add a waste allowance and cost the material.

Work a flight out from the floor-to-floor height: riser count, riser height, run and stringer length.

Calculate sample or population standard deviation with the full working shown.

Sunrise, sunset, solar noon and the three twilights for any date and coordinates.

Model a systematic withdrawal plan and find out whether the corpus lasts the distance.

Capacity and contents for cylindrical, rectangular and capsule tanks, including partial fill by depth.

Total daily energy expenditure across every activity level, with a macro split.

Estimate the tax deducted from each payslip, and what remains for the rest of the year.

Convert between kW, kVA, kVAr and line current for single- and three-phase supplies, with power factor.

Work out how many tiles and boxes a floor or wall needs, grout joints included.

Add and subtract durations, or find the time between two clock times including overnight.

Work out the tip and the total, split it between any number of people, and round it off.

Compare two tyre sizes for diameter, clearance and speedometer error.

Turns ratio from voltages or windings, with secondary current, primary draw and the impedance ratio it presents.

Solve a triangle from any three parts — sides, angles, area, altitudes and the ambiguous case.

Rank packs of different sizes by what they actually cost per gram, millilitre or item.

Add VAT to a net figure or extract it from a gross one, at any rate.

Add, subtract, dot and cross two vectors, with magnitudes, angle and projection.

Find the output of a two-resistor divider, or the resistor that hits a target voltage.

Voltage lost along a cable run, from its gauge, length, current and temperature.

Rolls needed for a room, counted in drops and allowing for the pattern repeat.

Convert frequency to wavelength and back, with antenna lengths worked out.

Convert between a value, its z-score, its percentile and the tail probabilities, in either direction.