All online calculators
Browse practical tools for loans, percentages, currency, calories, tiles, laminate, age and business days.
Rental yield calculator
Gross and net rental yield on a property.
Video file size calculator
Recording size from video and audio bitrate — in gigabytes and mebibytes.
Work hours calculator
Hours over a period from shift start and end with a break, night shifts included.
Bike gear ratio calculator
Bicycle gear ratio and the distance covered per pedal revolution.
Electricity usage calculator
Kilowatt-hours an appliance uses and what that costs.
Maximum heart rate calculator
Age-based pulse estimates and percentages of maximum or reserve, with formula population limits.
Moles calculator
Moles from a mass and a molar mass, plus the number of particles.
Momentum calculator
Signed momentum, mass or velocity from p = m · v.
Regular polygon calculator
Area, perimeter, apothem and angles of a regular polygon.
Return rate calculator
What share of orders came back.
Stair rise and run calculator
Step count, riser height, total run and pitch angle.
Stock duration calculator
How many days a stock lasts at a known rate of use.
Tire size calculator
Overall diameter, sidewall height and revolutions per kilometre from a tire code.
Torque calculator
Torque magnitude from force, application-point distance and angle.
Trip budget calculator
Accommodation, food, transport and activities — the full trip budget and the share per person.
Advertising ROI calculator
ROAS and simplified ROI from revenue and advertising spend.
Freelance rate calculator
The hourly rate that delivers your target income after tax and unbillable hours.
Heating power calculator
Heater or radiator power from room volume and a specific heat requirement.
Ideal gas law calculator
PV = nRT: the pressure or the volume of a gas from the rest.
IPv4 subnet calculator
Network address, mask, broadcast address and host count from CIDR notation.
Reading time calculator
How many minutes a text takes to read silently, and how long the same text takes aloud.
Test score percentage calculator
Turn correct answers into a percentage, with an optional pass mark.
GPA calculator
Grade point average weighted by credits, alongside the unweighted mean for comparison.
Internet data usage calculator
How many gigabytes a month adds up to at a given stream rate and hours per day.
Number to words converter
Write a whole number in words; the separate amount line is fixed to RUB and00 kopecks.
Position size calculator
Trade size from the risk you allow per account and the distance to the stop.
Revenue per employee calculator
Annual revenue divided by a whole employee count.
Rule of 72 calculator
How long money takes to double, and how far the shortcut is off.
Time zone difference calculator
Convert a time between two UTC offsets, midnight rollover included.
3D printing cost calculator
Material, electricity, wear and chosen markup in a printing-cost estimate.
Bulk material calculator
Volume and mass of gravel, sand or screenings for a base layer.
CTR calculator
Click-through rate from clicks and impressions, with cost per click.
Dew point calculator
The temperature at which air of this humidity starts giving up moisture.
LED resistor calculator
Series resistor for an LED, with the power it will dissipate.
Molar mass calculator
Molar mass from a chemical formula with each element's contribution broken out.
Password entropy calculator
Entropy of a uniformly random sequence and a search model at the supplied rate.
Recipe cost calculator
Cost of a dish from its ingredient list, and the price of a single serving.
Risk reward ratio calculator
Risk-to-reward ratio from three prices and the win rate needed to break even.
Shipping per unit calculator
What logistics adds to the cost of one item.
Correlation coefficient calculator
Pearson correlation for two series, together with the regression line.
Currency exchange cost calculator
What an exchange really costs: spread, percentage fee and flat charge together.
Debt payoff calculator — snowball and avalanche
Order and term for paying off several debts: snowball or avalanche.
Metal bar weight calculator
Mass of round, square and flat bar from the section size and length.
Raw to cooked weight calculator
Convert dry grain weight to cooked and back, along with the calories per portion.
Recipe scaling calculator
Rescale every ingredient in a recipe to a different number of servings.
ROAS calculator
Revenue ROAS and advertising return with the supplied margin.
Stopping distance calculator
Total stopping distance: reaction plus braking.
Tip calculator
Tip, total and an even split across the table.
Wind chill calculator
How much colder frost feels in wind — by the meteorological services' formula.
Baker's percentage calculator
Ingredient weights and dough hydration from baker's percentages of the flour.
Coffee brew ratio calculator
How much coffee a volume of water takes at a chosen brew ratio.
Compression ratio calculator
Compression ratio from swept and chamber volume.
Confidence interval calculator
Confidence interval for a mean from sample size, standard deviation and confidence level.
Engine displacement calculator
Displacement from bore, stroke and cylinder count.
FPS to frame time calculator
Convert between frames per second and milliseconds per frame.
Linear equation calculator
Solves ax + b = c and shows every step.
LTV calculator
Customer lifetime value from lifetime or churn.
Sample size calculator
How many respondents you need for a given accuracy.
Speed distance time calculator
Find speed, distance or time from the other two.
Voltage divider calculator
Output voltage, current and per-leg power of a two-resistor divider.
Water heating time calculator
How long it takes to heat water at a given power.
Air changes per hour calculator
Required airflow from room volume and the air change rate.
Binomial probability calculator
Probability of exactly k, at most k and at least k successes in a run of independent trials.
Gas oil mix ratio calculator
How much oil to add to petrol at a 1:N ratio.
Network bandwidth calculator
Estimate bandwidth from total users, their active share and explicit headroom.
Paper weight and sheets calculator
Ream mass from sheet size, grammage and sheet count.
Power to weight ratio calculator
Specific power in kW per tonne, hp per tonne and kg per hp.
Real return calculator
Return after inflation, by the exact formula and by subtraction.
Resistor network calculator
Total resistance of a circuit in series and in parallel.
Roasting time calculator
How long a joint needs in the oven from its weight and a per-kilo rate.
Wheel offset calculator
Offset ET, backspacing and how far the wheel moves.
Aspect ratio calculator
Reduce a resolution to its ratio, or find the missing side.
Asset depreciation calculator
Depreciation by three methods with salvage value and a year-by-year table.
Beam deflection calculator
Deflection of a simply supported beam under uniform or point load.
Capacitor charge and energy calculator
Charge, voltage or capacitance of a capacitor, plus the stored energy.
Cladding boards calculator
How many boards a wall takes once the overlap is accounted for.
Combinations and permutations calculator
Combinations and permutations, with or without repetition.
Doppler effect calculator
The heard frequency when the source or the listener moves.
GCD and LCM calculator
Greatest common divisor and least common multiple of a list of numbers.
Headphone power calculator
Estimated SPL and required RMS voltage/current from sensitivity at 1 mW.
kVA to kW calculator
Converting apparent power to active power through the power factor.
Luggage linear inches calculator
The sum of a suitcase's three sides against the airline limit.
Payback period calculator
How long an investment takes to pay for itself.
Pipe flow velocity calculator
Water velocity in a pipe from flow rate and inner diameter.
Trip cost calculator
Fuel and tolls for a journey, split between passengers.
Arithmetic progression calculator
The nth term and the sum of an arithmetic progression from the first term and the common difference.
Baluster spacing calculator
How many balusters a run takes at a maximum permitted gap.
Belt length calculator
Approximate open-belt length from centre distance and pulley pitch diameters.
Buoyant force calculator
Archimedes' force, the body's weight, and whether it floats.
Coordinate converter — DMS and decimal degrees
Convert coordinates between degrees-minutes-seconds and decimal degrees.
CPM calculator
Cost per thousand impressions, in any direction.
Curtain fabric calculator
How much fabric curtains need at a given fullness.
Divisors calculator
Positive divisors: the first 40, full count, sum and proper-divisor sum.
Hooke's law calculator
Spring force, extension or rate, plus the energy stored.
Inverter power calculator
Battery draw of an inverter from its output power and efficiency.
Lakh and crore converter
Convert between lakh, crore and the familiar thousands and millions.
Lease payment calculator
Monthly lease payment with a residual value.
Miter angle calculator
The cut angle for joining two pieces at a corner.
Reading speed calculator
Words per minute from a timed passage, plus time for a whole book.
RMS voltage calculator
Convert between peak, peak-to-peak and RMS voltage for sine, square and triangle waves.
Takt time calculator
How much time you may spend per unit to keep up with demand.
Tank volume calculator
Full tank volume and the volume held at a given level.
ABV from gravity calculator
Alcohol strength from original and final gravity.
Alcohol units calculator
How much pure alcohol and how many standard units a serving holds.
Battery runtime calculator
How long a battery lasts under a given load.
Coulomb's law calculator
The force between two point charges.
Decibel calculator
Add noise levels and convert a ratio of quantities into decibels.
Epoxy resin calculator
How much resin and hardener a pour needs.
Factorial calculator
Exact n! for whole numbers up to 170.
Fibonacci calculator
The nth Fibonacci number, the sum of the series and the ratio between neighbours.
Free fall calculator
Impact speed and fall time from a height or from a duration.
Inclined plane calculator
Force along the slope, friction and acceleration.
Moment of inertia calculator
Moment of inertia of a rod, disk, ring or sphere about an axis.
Projectile motion calculator
Range, flight time and apex height of a body thrown at an angle.
Capacitors in series and parallel calculator
Total capacitance of capacitors wired in series or in parallel.
Dollar-cost averaging calculator
Average price and outcome when buying the same amount at regular intervals.
Escape velocity calculator
The speed needed to leave a planet, from its mass and radius.
Files on disk calculator
How many files of a given size fit on a drive.
Final grade calculator
The exam mark you need to reach a target final grade.
Heat index calculator
An illustrative heat index from the unadjusted regression.
Inverse square law calculator
How intensity falls with distance from a point source.
Lever and mechanical advantage calculator
Lever balance: the force on the second arm and the advantage gained.
Mass-energy equivalence calculator
Rest energy of a mass from E=mc² in joules, kilowatt-hours and tonnes of TNT.
Photon energy calculator
Photon energy and frequency from wavelength.
RC circuit calculator
Cutoff frequency and time constant of a resistor with a capacitor.
Skirting board calculator
Skirting length around a room, less doorways, cut into planks.
Speed of sound calculator
The speed of sound in air from temperature, with a conversion to kilometres per hour.
Transformer turns ratio calculator
Turns, voltages and currents of an ideal transformer.
Absolute humidity calculator
How many grams of water are in a cubic metre of air.
Air density calculator
Density of moist air from temperature, pressure and humidity.
Beam bending stress calculator
Bending stress from the moment and the shape of the beam's cross-section.
Boiling point calculator
The boiling point of water at a given altitude above sea level.
Combined gas law calculator
A gas moving between two states: p₁V₁/T₁ = p₂V₂/T₂.
LC resonant frequency calculator
Tank circuit frequency from inductance and capacitance.
Model scale calculator
Convert sizes between the original and the model at a 1:N scale.
Orbital period calculator
Orbital period from the central body mass and the orbit radius.
Pendulum period calculator
Period of a simple pendulum from its length.
Pool fill time calculator
How long a pool takes to fill at a known flow rate.
RAID calculator
Usable capacity of a RAID array, its failure tolerance and the efficiency of each level.
Rainwater harvesting calculator
How much water a roof collects from a given amount of rain.
Specific heat calculator
How much energy it takes to heat a body: Q = c·m·ΔT.
Stress, strain and Young's modulus calculator
Stress, strain and Young's modulus for a specimen in tension.
Unix timestamp converter
Convert between Unix time and a UTC date, both directions.
De Broglie wavelength calculator
The wavelength of a particle from its mass and speed.
Half-life calculator
Remaining amount from a half-life, or the time to reach a given remainder.
HEX, RGB and HSL colour converter
Convert a colour from HEX to RGB and HSL with a per-channel breakdown.
NE555 astable timer calculator
Frequency, period and duty cycle of an NE555 multivibrator from two resistors and a capacitor.
Picture frame mat calculator
Outer mat dimensions and border area from a visible image opening.
Quartile and percentile calculator
Quartiles, interquartile range, whisker bounds and outliers from a list of numbers.
Thermal conduction calculator
Heat flow, thermal resistance and U-value of a single layer.