New Calculators

Calculate a vehicle's total stopping distance from its speed, reaction time, and tyre–road friction — stopping distance = reaction distance (v·t) + braking distance (v²/(2·μ·g)).

Calculate the number of usable IPv4 hosts in a subnet (2^(32 − prefix) − 2) from its CIDR prefix length, for prefixes from /0 to /30.

Calculate the surface-area-to-volume ratio of a spherical cell from its radius (SA/V = 3/r), along with the surface area (4πr²) and volume ((4/3)πr³).

Calculate the surface gravity (g = G·M/r²) in m/s² of a planet or moon from its mass and radius, plus how many Earth gravities that is.

Calculate the surface (cutting) speed (v = π × d × n) in metres per minute of a rotating part from its diameter and rotational speed.

Calculate the one-sample t-statistic, t = (x̄ − μ) / (s / √n), from a sample mean, hypothesized population mean, sample standard deviation, and sample size.

Calculate the tangential (linear) velocity (v = ω × r) in metres per second of a point on a rotating body from its angular velocity and radius.

Calculate the terminal velocity of a falling object, v = √(2mg / ρACd), in metres per second from its mass, area, drag coefficient, and fluid density.

Calculate the linear thermal expansion (ΔL = α·L₀·ΔT) of a solid — the change in length and the final length from its expansion coefficient, original length, and temperature change.

Calculate the conductive thermal resistance (R = L ÷ kA) in K/W of a flat layer from its thickness, thermal conductivity, and area.

Calculate the real, apparent, and reactive power of a balanced three-phase AC system from line voltage, line current, and power factor — P = √3 × V_L × I_L × pf.

Calculate the thrust-to-weight ratio (TWR = thrust ÷ (mass × g)) of a rocket, drone, or jet from its thrust and mass — a ratio above 1 means it can lift off.

Calculate torque (τ = F × r) in newton-metres from a force and a lever-arm length, with the force applied perpendicular to the lever arm.

Convert engine torque (lb-ft) and rpm to power in horsepower and kilowatts — horsepower = (torque × rpm) / 5252, kilowatts = horsepower × 0.7457.

Calculate the efflux speed of fluid leaving an opening below the surface with Torricelli's law — v = √(2gh). The exit speed equals a free fall from the same height and ignores fluid density.

Calculate the surface area and volume of a torus (ring/donut) from its major and minor radius — surface = 4π²Rr, volume = 2π²Rr².

Calculate the total magnification of a compound light microscope by multiplying the objective-lens magnification by the eyepiece (ocular) magnification.

Calculate the total surface area, lateral surface area, and cross-section area of a triangular prism from its three sides and length — uses Heron's formula.

Calculate the volume and cross-sectional area of a right triangular prism from its base, triangle height, and length — volume = ½ × base × height × length.

Calculate your typing speed in words per minute (WPM) and words per hour from the words you typed and the time it took.

Work out the price per unit and the price per 100 units from a total price and quantity, so you can compare pack sizes and spot the better-value deal.

Calculate the magnitude (length) of a 3D vector, |v| = √(x² + y² + z²), from its x, y, and z components.

Calculate the DC voltage drop (Vdrop = 2 × L × I × ρ / A) in volts and the power lost in a wire run from the current, length, resistivity, and cross-section.

Calculate the volumetric flow rate (Q = A·v) in cubic metres per second and litres per second of a fluid from its cross-sectional area and velocity.

Convert watts and volts to amps and ohms instantly using Watt's law (I = P ÷ V) — useful for sizing fuses, cables, and circuit breakers for any DC or resistive AC load.

Find the ISO 8601 week number (Kalenderwoche / KW) for any date, plus the day of the year and the days remaining.

Calculate the weight (gravitational force, W = mg) on a mass in newtons from its mass and the local gravitational acceleration.

Find out what you would weigh on the Moon, Mars, Jupiter, and every other planet by scaling your Earth weight by each body's surface gravity.

Calculate the weighted average of two value and weight pairs — (v₁·w₁ + v₂·w₂) / (w₁ + w₂) — the classic grade- and score-weighting formula.

Find the unknown resistance of a balanced Wheatstone bridge from its three known resistors — Rx = (R2 × R3) / R1.

Calculate the peak emission wavelength of a blackbody (λ_max = b/T) in metres and nanometres from its absolute temperature using Wien's displacement law.

Calculate the wind chill (feels-like) temperature in degrees Celsius from the air temperature and wind speed using the official NWS metric formula.

Calculate the power output of a wind turbine (P = ½ρAv³Cp) in watts from the air density, rotor swept area, wind speed, and power coefficient.

Calculate the electrical resistance (R = ρL/A) in ohms of a wire from its resistivity, length, and cross-sectional area.

Convert fresh (cake) yeast to active dry yeast and instant yeast using the standard baking ratios (active dry = fresh ÷ 2.5, instant = fresh ÷ 3).

Calculate Young's modulus (E = stress / strain) in pascals and the tensile stress of a stretched material from force, area, length, and length change.

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.

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

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.

Find the nth term and the sum of the first n terms of any arithmetic sequence from its first term and common difference.

Calculate average acceleration from initial velocity, final velocity, and time — acceleration = (vf − vi) ÷ t, in m/s².

Calculate the stored charge and energy of a capacitor from its capacitance and voltage — charge = C × V and energy = ½ × C × V².

Calculate the energy stored in a charged capacitor (E = ½CV²) in joules from its capacitance and voltage.

Convert your cat's age in years to human years using the standard AAHA feline life-stage conversion, with a worked breakdown of how the figure is reached.

Calculate the centripetal force (F = mv²/r) in newtons that keeps an object moving in a circle, from its mass, speed, and radius.

Calculate the area, circumference, and diameter of a circle from its radius — area = πr², circumference = 2πr, diameter = 2r.

Calculate the coefficient of variation from a mean and a standard deviation — CV% = (σ ÷ μ) × 100.

Work out how much ground coffee to use for any amount of water at your chosen brew ratio (1 : X), from strong 1:15 to mild 1:18.

Calculate the number of combinations C(n, r) — how many ways to choose r items from n when order does not matter, using C(n, r) = n! ÷ (r! × (n − r)!).

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.