What Is Time Dilation?
Time dilation is the difference in elapsed time measured by observers moving relative to each other. In special relativity, fast motion makes moving clocks run slower than clocks at rest.
How This Time Dilation Calculator Works
Enter a speed and a time interval to estimate the effect predicted by Einstein's special relativity. The calculator compares the moving frame with the rest frame and shows how much time would elapse in each.
Why Does Time Slow Down at High Speed?
The speed of light is constant for every observer, so space and time must adjust when objects move very quickly. That adjustment shows up as time dilation.
The Time Dilation Formula
The standard special-relativity equation uses the Lorentz factor, gamma = 1 / sqrt(1 - v^2 / c^2). As speed approaches the speed of light, the factor grows and the moving clock ticks more slowly.
A Simple Example
At everyday speeds, the effect is tiny. At a significant fraction of light speed, the difference becomes noticeable and the moving clock falls behind the rest-frame clock.
Does Time Dilation Happen in Real Life?
Yes. Time dilation is measured in particle experiments, in high-speed travel, and in GPS corrections. It is a real, tested prediction of relativity.
Frequently Asked Questions
What is time dilation?
It is the way time can pass at different rates for observers in relative motion.
How do you calculate time dilation?
Use the Lorentz factor from special relativity and compare the moving frame with the rest frame.
Is time dilation real?
Yes. It is measured in experiments and corrected for in technologies such as GPS.
Does time dilation only happen near the speed of light?
The effect exists at all speeds, but it becomes important only when the speed is very high.
Is this the same as gravitational time dilation?
No. This page covers motion-based time dilation, while gravitational time dilation comes from strong gravity.