Gravitational Time Dilation Calculator

Gravitational time dilation is the phenomenon where time passes more slowly in stronger gravitational fields, as predicted by Einstein's General Theory of Relativity. An observer closer to a massive object — like a planet, star, or black hole — experiences time ticking more slowly compared to someone far away in weaker gravity. This isn't a mechanical effect; gravity literally curves spacetime itself.

The calculator uses the Schwarzschild gravitational time dilation equation: Δt′ = Δt × √(1 − 2GM / rc²), where G is the gravitational constant (6.674×10⁻¹¹ m³kg⁻¹s⁻²), M is the object's mass, r is the distance from its center, and c is the speed of light (≈ 3×10⁸ m/s). Δt is the time elapsed far from gravity, and Δt′ is the shorter time experienced near the massive object.

Yes, it has been experimentally confirmed multiple times. GPS satellites experience measurable time dilation due to Earth's gravity and must correct for it to maintain accuracy — without corrections, GPS positions would drift by kilometers per day. The Pound–Rebka experiment in 1959 also directly measured gravitational time dilation using gamma rays traveling vertically.

Yes — the farther you are from a massive object, the weaker the gravitational field and the faster time flows relative to someone on the surface. Astronauts on the International Space Station actually experience two competing effects: gravitational time dilation (which speeds their time up relative to Earth's surface) and velocity-based special relativistic dilation (which slows it). The net result is that ISS clocks run very slightly faster than Earth clocks.

The Schwarzschild radius (rs = 2GM/c²) is the critical radius at which the escape velocity equals the speed of light — forming a black hole's event horizon. If a mass were compressed below its Schwarzschild radius, it would collapse into a black hole. The dilation formula breaks down at this boundary (the factor under the square root becomes zero or negative), meaning time effectively stops for an outside observer at the event horizon.

Spacetime is the four-dimensional fabric that combines the three dimensions of space with the dimension of time into a single continuum. Einstein's general relativity describes gravity not as a force, but as the curvature of this spacetime fabric caused by mass and energy. Massive objects create 'wells' in spacetime, and both matter and light follow the curved paths this geometry creates.

Extremely significant. At the event horizon of a black hole, the dilation factor reaches zero — time appears to stop entirely from the perspective of a distant observer. Even at a safe distance from a stellar black hole (say, 1.5 times the Schwarzschild radius), clocks tick dramatically slower. The movie Interstellar depicted this accurately: one hour on the water planet near the black hole Gargantua equated to seven years on Earth.

Yes, as long as the distance from the center is greater than the Schwarzschild radius of the object (otherwise it would be inside a black hole). You can use it for Earth, the Sun, neutron stars, white dwarfs, or custom hypothetical objects. The calculator will warn you if your input distance is dangerously close to or within the Schwarzschild radius.