New Calculators

Calculate the total and lateral surface area of a square pyramid from its base edge and slant height — total = b² + 2bl, lateral = 2bl.

Calculate the area, perimeter, and arc length of a quarter circle from its radius — area = ¼πr², arc length = ½πr, perimeter = ½πr + 2r.

Find which calendar quarter (Q1–Q4) a date falls in, how many days into the quarter you are, and how many days remain in the quarter.

Calculate how much of a radioactive substance is left after decay with N = N0 × (1/2)^(elapsed / half-life), from the initial amount, elapsed years, and half-life.

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

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

Calculate the cutoff frequency and time constant of a first-order RC high-pass filter from its resistance and capacitance — f_c = 1 / (2π × R × C).

Calculate the cutoff frequency and time constant of a first-order RC low-pass filter from its resistance and capacitance — f_c = 1 / (2π × R × C).

Calculate the redshift z = (λ_observed − λ_rest) / λ_rest of a spectral line and the low-redshift recession velocity of a galaxy from its wavelengths.

Calculate the refractive index (n = c / v) of a medium from the speed of light within it, using the exact speed of light in vacuum.

Calculate the volume and surface area of a regular dodecahedron from its edge length — volume = ((15+7√5)/4)·a³, surface area = 3√(25+10√5)·a².

Calculate the volume and surface area of a regular icosahedron from its edge length — volume = (5(3+√5)/12)·a³, surface area = 5√3·a².

Calculate the volume and surface area of a regular octahedron from its edge length — volume = (√2/3)·a³, surface area = 2√3·a².

Calculate the volume, surface area, and height of a regular tetrahedron from its edge length — volume = a³/(6√2), surface area = √3·a², height = a·√(2/3).

Calculate the magnitude of the resultant of two forces acting at an angle using R = √(F1² + F2² + 2·F1·F2·cosθ).

Calculate a room's Sabine reverberation time (RT60) and total absorption from its volume, surface area, and average absorption coefficient — RT60 = 0.161·V/A, A = S·α.

Calculate the Reynolds number (Re = ρvL/μ) from fluid density, velocity, characteristic length, and dynamic viscosity, and see whether the flow is laminar or turbulent.

Work out how much water to use for any amount of rice at your chosen water-to-rice ratio — from 1.5:1 for basmati to 2.5:1 for brown rice.

Calculate the hypotenuse, area, perimeter, and acute angles of a right triangle from its two legs — hypotenuse = √(a²+b²), area = ½ab, angles via atan.

Calculate the time constant of an RL (resistor–inductor) circuit from its inductance and resistance — τ = L / R — plus the time to reach steady state.

Calculate the RMS voltage (V_rms = V_peak / √2) and peak-to-peak voltage of a sine wave from its peak voltage (amplitude).

Calculate the road or slope grade as a percentage ((rise / run) × 100) and the slope angle in degrees from a vertical rise and a horizontal run.

Calculate the change in velocity (Δv = ve · ln(m0/mf)) of a rocket from its exhaust velocity and its wet and dry mass using the Tsiolkovsky rocket equation.

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

Calculate the wavelength of a hydrogen spectral line with the Rydberg equation (1/λ = R·(1/n1² − 1/n2²)) from the two principal quantum numbers.

Calculate the sample size needed for a survey or poll from your confidence level (z-score), expected proportion, and margin of error: n = (z²·p·(1−p))/E².

Convert a measured model or map length into the real-world length for any 1:N scale, plus the reverse scaled-down length.

Calculate the Schwarzschild radius (event horizon) r_s = 2GM/c² of any mass in metres and kilometres — the radius at which it would become a black hole.

Convert any decimal number into scientific notation — a coefficient between 1 and 10 multiplied by a power of ten — and read off the mantissa and exponent.

Calculate the physical width and height of a screen from its diagonal size and aspect ratio (16:9, 4:3, 21:9) in the same unit as the diagonal.

Calculate the area, perimeter, arc length, and diameter of a semicircle from its radius — area = ½πr², perimeter = πr + 2r, arc = πr.

Round any number to a chosen count of significant figures, with a worked explanation of how the rounding place is found.

Calculate the skin depth of an AC current in a conductor from the frequency, resistivity, and relative permeability — δ = √(ρ / (π × f × µ₀ × µr)).

Calculate the angle of refraction with Snell's law (n1·sin θ1 = n2·sin θ2) from the two refractive indices and the angle of incidence.

Calculate the signal-to-noise ratio in decibels (SNR = 20·log10(signal/noise)) from a signal and a noise amplitude in volts.

Calculate the daily energy output (kWh) of a solar panel or array from its wattage, the site's peak sun hours, and a performance ratio.

Calculate the stock volume needed and the diluent to add using C₁V₁ = C₂V₂ when diluting a solution to a target concentration and final volume.

Calculate the sound intensity level in decibels (L = 10 · log₁₀(I/I₀), with I₀ = 1e-12 W/m²) from a measured sound intensity in watts per square metre.

Calculate how a point source's sound pressure level drops with distance in a free field — L2 = L1 − 20·log10(d2/d1). Doubling the distance lowers the level by about 6 dB.

Calculate the specific gravity (relative density) of a substance from its density and a reference density such as water at 4 °C (1000 kg/m³).

Calculate the specific heat capacity c = Q / (m·ΔT) in J/(kg·K) from the heat energy added, the mass, and the temperature change of a sample.

Calculate the specific impulse (Isp) of a rocket engine in seconds from its thrust and propellant mass flow rate.

Calculate the specific weight (weight density, γ = ρ·g) of a material in N/m³ from its density and the local gravitational acceleration.

Calculate the curved surface, base radius, and total surface area of a spherical cap from the sphere radius and cap height — curved surface = 2πRh, base radius = √(h(2R−h)).

Calculate the volume of a spherical sector from the sphere radius and the cap height — volume = (2/3)πR²h.

Calculate the volume of a spherical segment (a zone of a sphere between two parallel planes) from the two base radii and the height — volume = (πh/6)(3a² + 3b² + h²).

Calculate the volume of a spherical wedge (an orange slice) from the sphere radius and the wedge angle in degrees — volume = (2/3)·R³·α, with α in radians.

Calculate the period and frequency of a mass-spring oscillator from its mass and spring constant — period = 2π√(m ÷ k) and frequency = 1 ÷ period.

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.

Calculate the radiated power of an ideal blackbody (P = σAT⁴) in watts from its surface area and absolute temperature using the Stefan-Boltzmann law.