All Calculators

Browse our complete collection of free online calculators, organized by category.

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Acres Per Hour Calculator

Estimate mowing productivity in acres per hour from your cutting width, ground speed, and efficiency — plus hours per acre and time to finish an area.

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Air Conditioner BTU Calculator

Estimate the air conditioner cooling capacity (BTU per hour) you need from your room size, using the 20 BTU per square foot rule of thumb.

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Beaufort Scale Calculator

Convert any wind speed in km/h to the Beaufort force (0–12) and metres per second — the scale used in marine and weather forecasts worldwide.

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Blue Hour Calculator: Exact Morning & Evening Times

Find exact morning and evening blue hour times for your location. Plan your photography shoot with our calculator, featuring weather viability and phase splits.

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Board Foot Calculator

Calculate the board feet of lumber from its thickness, width, and length using the formula (T x W x L) / 12.

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Ceiling Fan Size Calculator

Work out which ceiling fan blade span suits your room, and the airflow rating to look for when you compare models.

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Concrete Calculator

Work out how much concrete you need for a rectangular slab — the volume in cubic metres and the number of pre-mix bags to buy, based on each bag's yield.

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Fence Calculator

Calculate how many posts and fence sections a straight fence run needs from its total length and the spacing between posts.

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Flooring Calculator

Work out the floor area of your room and how many boxes of laminate, vinyl, or hardwood flooring you need, including a waste allowance for cuts.

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Grass Seed Calculator

Work out how much grass seed you need to sow or overseed a lawn — the amount in kilograms and grams, based on your lawn area and seed rate.

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Gravel Calculator

Work out how much gravel you need to cover an area to a given depth — the volume in cubic metres and the weight in tonnes, based on the stone's density.

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Heat Pump Size Calculator

Estimate the heat output a heat pump needs to deliver for your home, including the allowance for hot water.

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Mulch Calculator

Work out how much mulch you need to cover a bed — in cubic yards, cubic feet, and standard 2-cubic-foot bags — from the area and the depth you want.

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Paint Calculator

Work out how many litres of paint you need from your wall area, the number of coats, and the paint's coverage per litre.

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Planet Visibility Calculator

Use our planet visibility calculator to find out which planets are visible tonight. Get exact altitude, direction, and moon glare data for your location.

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Pool Pump Size Calculator

Work out the flow rate your pool pump has to sustain to turn the water over in the time you want.

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Rainwater Harvesting Calculator

Estimate how many litres of rainwater you can collect from a roof from its area, the rainfall, and a runoff coefficient.

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Ramp Length Calculator

Calculate the horizontal run and sloped length of an accessibility ramp from a vertical rise and a slope ratio such as ADA 1:12.

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Roof Pitch Calculator

Calculate the roof pitch angle in degrees and the slope as a percentage from a vertical rise and a horizontal run.

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Rug Size Calculator

Find the largest standard rug that fits your room while leaving an even border of bare floor.

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Ski Size Calculator

Find the right ski length for your height, ability, and skiing style, with a suggested range to shop within.

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Stair Calculator

Calculate how many steps a staircase needs from its total rise and your target riser height, plus the exact step height once the rise is split evenly.

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Suit Size Calculator

Enter your chest, waist and height to get the jacket number, the length letter, the EU size and the trouser waist that comes with them.

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Surfboard Volume Calculator

Find the recommended surfboard volume in litres for your weight, ability, and fitness — with a suggested range to shop within.

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Tile Calculator

Work out how many tiles you need to cover a floor area, including a waste allowance for cuts and breakages.

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Wallpaper Calculator

Work out how many rolls of wallpaper you need to cover a wall area, including a waste allowance for pattern matching and trimming.

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Mathematics

German Abitur Grade Calculator (KMK Scale)

Convert your exam percentage to the 15-point KMK grading scale used across all German states. Instantly see your Notenpunkte, Schulnote, and how close you are to the next grade.

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Absolute Humidity Calculator

Calculate the absolute humidity (grams of water vapour per cubic metre of air) from the air temperature (°C) and relative humidity (%) using the standard meteorological approximation.

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Acceleration Converter

Convert acceleration between m/s², ft/s², standard gravity (g), galileo, km/h/s, and mph/s — instantly and with exact, m/s²-based conversion factors.

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ACT Test Score Calculator

Calculate your ACT composite score from the four section scores (English, Math, Reading, Science) and see the national percentile rank.

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Air Density Calculator

Calculate the density of dry air (kg/m³) from its absolute pressure and temperature using the ideal gas law, ρ = P / (R × T).

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Air Pressure at Altitude Calculator

Calculate the atmospheric pressure at a given altitude with the barometric formula for the troposphere — enter a height in metres to get the pressure in pascals.

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Amps to Watts Calculator

Convert amps and volts to watts instantly using Watt's law (P = V × I). Also computes resistance in ohms — handy for household circuits, EV charging, and electronics projects.

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Angle Between Vectors Calculator

Calculate the angle between two 3D vectors from cosθ = (A·B) / (|A| |B|), with the result in degrees from 0 to 180.

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Angle Converter

Convert angles between degrees, radians, gradians (gon), arcminutes, arcseconds, and turns — instantly and with exact, degree-based conversion factors.

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Angular Acceleration Calculator

Calculate angular acceleration (α = (ω₂ − ω₁) / t) in rad/s² from an initial and final angular velocity over a time interval.

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Angular Frequency Calculator

Convert an ordinary frequency in hertz into the angular frequency ω = 2πf in radians per second.

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Angular Momentum Calculator

Calculate the angular momentum (L = m·v·r) of a point mass moving in a circle, in kg·m²/s, from its mass, tangential speed, and radius.

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Angular Size Calculator

Calculate the angular size (apparent size) of an object in radians and degrees from its physical size and distance using the small-angle approximation.

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Angular Velocity Calculator

Calculate angular velocity (ω = 2π·f) in rad/s from a rotational frequency, plus the tangential speed at a given radius.

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Annular Sector Area Calculator

Calculate the area and arc lengths of an annular sector (a slice of a ring) from its inner radius, outer radius, and central angle in degrees.

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Annulus (Ring) Area Calculator

Calculate the area of an annulus (a flat ring) and its width from the outer and inner radii — area = π(R² − r²), width = R − r.

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583 calculators available