Mathematics

Weighted and unweighted high-school GPA side by side on the US 4.0 scale, so you can see exactly what honors and AP coursework adds.

Calculate spring force and elastic potential energy from a spring constant and displacement using Hooke's law — force = k × x and PE = ½ × k × x².

Calculate the distance to a receding galaxy with Hubble's law (d = v / H₀) in megaparsecs and millions of light-years from its recession velocity.

Calculate the Canadian humidex "feels-like" index from the air temperature (°C) and dew point (°C) — humidex = T + 0.5555·(e − 10), with e from the vapour-pressure formula.

Calculate the hydrostatic pressure (P = ρgh) in pascals and kilopascals from a fluid's density and depth.

Solve the ideal gas law PV = nRT for the amount of substance n = (P × V) / (R × T) in moles from the pressure, volume, and temperature of a gas.

Calculate the average impact force of a collision from the work–energy principle — force = ½mv² / stopping distance — plus the kinetic energy and equivalent g-force.

Calculate the magnitude of a series RLC impedance (|Z| = √(R² + X²)) in ohms from a resistance and a net reactance.

Calculate impulse — J = F × Δt — the force applied over a time interval, which equals the change in momentum (N·s = kg·m/s).

Calculate the inductive reactance (Xl = 2π × f × L) in ohms of a coil or inductor from its inductance and the AC signal frequency in hertz.

Calculate the energy stored in an inductor's magnetic field (E = ½LI²) in joules from its inductance and the current flowing through it.

Calculate the initial compass bearing (forward azimuth) from one point on Earth to another from their latitude and longitude — the direction in degrees (0° = North, 90° = East, 180° = South, 270° = West) you would set off in.

Calculate how the intensity of a point source (light, sound, radiation) falls with distance — I₂ = I₁·(d₁/d₂)². Doubling the distance quarters the intensity.

Calculate the area, height, perimeter, base angle, and apex angle of an isosceles triangle from its base and equal-side leg — area = ½ × base × height.

Calculate the kinetic energy (KE = ½mv²) in joules and the linear momentum of a moving object from its mass and velocity.

Calculate the area of a kite from its two diagonals — area = ½ × p × q.

Generate a fair grading scale with a custom passing threshold (Knick), as used in German schools. Instantly calculate exact point boundaries for German grades 1 to 6.

Convert kVA to kW instantly — enter apparent power and power factor to get real power in kilowatts and reactive power in kVAR using the power triangle formula.

Convert kilowatts to kilovolt-amperes instantly by entering your real power and power factor — essential for sizing generators, transformers, and UPS systems correctly.

Calculate the latent heat (Q = m·L) in joules and kilojoules absorbed or released during a phase change from the mass and specific latent heat.

Find the third side of a triangle from two sides and the included angle using the law of cosines: c = √(a² + b² − 2ab·cos(C)).

Find an unknown side of a triangle with the law of sines: enter a side, its opposite angle, and a second angle to get b = a · sin(B) / sin(A).

Calculate the resonant frequency of an LC circuit from its inductance and capacitance — f = 1 ÷ (2π√(L × C)).

Add up order processing, production, and transit time to find total lead time, and compute the reorder point from daily demand and safety stock.

Calculate the series current-limiting resistor for an LED (R = (Vs − Vf) / I) in ohms and the power it must dissipate from the supply voltage, forward voltage, and current.

Convert length between metric and imperial units — millimetres, centimetres, metres, kilometres, inches, feet, yards, miles, and nautical miles.

Apply the law of the lever to find the effort force (effort = load × loadArm ÷ effortArm) in newtons and the mechanical advantage of a lever.

Find the equation of a straight line through two points in slope-intercept form y = m·x + b — the slope and the y-intercept, computed instantly.

Estimate the value y at any point x on the straight line between two known points (x1, y1) and (x2, y2) using the linear interpolation formula.

Calculate the logarithm of any number to any base with log_b(x) = ln(x) / ln(b), plus the natural logarithm ln(x).

Calculate the Lorentz factor (γ = 1 / √(1 − (v/c)²)) of special relativity from a speed, plus that speed as a percentage of the speed of light.

Calculate the Lorentz force (F = qvB) on a charge moving perpendicular to a magnetic field, in newtons, from the charge, velocity, and field strength.

Convert lumens to lux by dividing luminous flux by the area in square metres — find out how bright a room or surface will be from a given light source.

Convert lumens to watts by dividing luminous flux by efficacy (lm/W) — compare LED, CFL, halogen, and incandescent bulbs to find the right wattage for your target brightness.

Calculate the luminosity of a star (L = 4πR²σT⁴) in watts and in solar luminosities from its radius and surface temperature.

Convert lux to foot-candles instantly — enter an illuminance reading in lux (lm/m²) and get the equivalent in foot-candles (lm/ft²), the US/imperial unit used in lighting standards and photometry.

Convert illuminance in lux to total luminous flux in lumens over an area (lumens = lux × area), for sizing lights and checking lighting levels.

Calculate the Mach number (M = v / a) of an object from its speed and the local speed of sound — find out if motion is subsonic, sonic, supersonic, or hypersonic.

Calculate the magnetic flux (Φ = B × A) in webers for a magnetic field perpendicular to a flat surface, from the field strength and the area.

Calculate the magnetic force (F = BIL) in newtons on a current-carrying wire in a magnetic field from the field strength, current, and wire length.

Calculate the linear magnification (m = image height / object height) and its percentage from an image and object measured in the same unit.

Convert a battery capacity in mAh to energy in watt-hours (Wh = mAh × V / 1000) and kilowatt-hours using the pack voltage.

Calculate profit margin and markup from a cost and a selling price, with the profit per unit shown alongside.

Calculate the selling price and profit from a cost and a markup percentage, with a clear explanation of how markup differs from margin.

Calculate the mass flow rate (ṁ = ρ·A·v) in kg/s and the volumetric flow rate of a fluid from its density, cross-sectional area, and velocity.

Calculate the rest energy of a mass with Einstein's mass-energy equivalence — energy = mass × c², where c is the speed of light.

Calculate mechanical advantage from load and effort force — MA = load force ÷ effort force.

Convert milligrams to millilitres and back. Milligrams measure mass and millilitres measure volume, so you need the concentration — and this asks for it.

Find the midpoint of the line segment between two points (x1, y1) and (x2, y2) — midpoint = ((x1 + x2) / 2, (y1 + y2) / 2) — the exact centre halfway between them.

Calculate a mod n — the remainder after dividing the dividend by the divisor — plus the integer quotient, using the floored modulo definition.