Relativity Calculators
Last updated: September 2026
Gravitational Time Dilation Calculator
Calculates how gravity slows time near massive objects using Einstein's general relativity.
Relativistic Velocity Addition Calculator
Computes the combined velocity of two objects moving at relativistic speeds, preventing any result from exceeding the speed of light.
Relativistic Energy Calculator
Compute the total relativistic energy E = γmc² of a particle from its rest mass and velocity.
Relativistic Doppler Shift Calculator
Computes the observed frequency of light or radio waves when the source and observer move relative to each other at relativistic speeds.
Time Dilation Calculator (Velocity)
Calculates the dilated (coordinate) time experienced by a stationary observer when a moving clock ticks off a given proper time at relativistic speeds.
Mass-Energy Equivalence Calculator
Converts mass directly into its equivalent energy using Einstein's E = mc².
Relativistic Momentum Calculator
Compute the relativistic momentum p = γmv of a particle from its rest mass and velocity.
Rest Mass Energy Calculator
Calculates the intrinsic energy locked in an object's mass using Einstein's famous E = mc².
Lorentz Factor Calculator
Compute the Lorentz factor γ = 1/√(1 − (v/c)²), the central quantity of special relativity that scales time dilation, length contraction, relativistic mass, momentum, and energy.
Relativistic Doppler Effect Calculator
Compute the observed frequency and wavelength when a light source moves toward or away from you at relativistic speeds.
Time Dilation Calculator
Compute the time experienced by a stationary observer for a moving clock that ticks through a given proper time, using special relativity.
Length Contraction Calculator
Compute the contracted length of an object measured by an observer relative to whom it moves at high velocity, using special relativity.
Relativistic Escape Velocity Calculator
Calculates the escape velocity from a massive body using a relativistic correction for the Schwarzschild geometry.
Cosmological Redshift Calculator
Compute the cosmological redshift (z), recession velocity, or distance of a galaxy from its observed vs.
Schwarzschild Radius Calculator
Compute the Schwarzschild radius — the event horizon size of a non-rotating black hole — from its mass via r_s = 2GM/c².
Gravitational Redshift Calculator
Compute the observed frequency of light or electromagnetic radiation emitted near a massive object, accounting for gravitational redshift predicted by General Relativity.
Lorentz Transformation Calculator
Transforms the spacetime coordinates (x, t) of an event from one inertial reference frame to another moving at relativistic velocity.
Twin Paradox Calculator
Calculates the final age of a traveling twin after a high-speed space journey, illustrating how relativistic time dilation causes the traveler to age less than the twin who stays on Earth.