Created By : awnish

Reviewed By : Phani Ponnapalli

Last Updated : Apr 10, 2023

Free online Time Dilation Calculator tool will give the result as the time dilation of the observer. Give 2 inputs time interval and observer velocity details and click the calculate button to avail the relative time of the observer in a short span of time.

Choose a Calculation
Time interval (Δt):
Observer velocity (v):

Steps to Calculate Time Dilation

Below provided is the step by step proess to compute the time dilation of an observer easily.

  • Obtain the time interval and observer velocity
  • Divide the square of the velocity by the square of the light speed.
  • Subtract it from the 1 and apply square root to the result.
  • Divide the time interval by the above result to check the relative time value.

Time Dilation Formula

Time dilation is a special kind of relativity. It is a measure of the elapsed time that measure using two clocks. The two reference frames are proper time and observer time.

The time dilation principle states that time is not perceived in the same way by everyone. Its equation is defined as

Δt' = γΔt = Δt/√(1 - v²/c²)


Δt' is the time that has passed as measured by the travelling observer or relative time

Δt is the time that has passed as measured by a stationary observer

v is the speed of the travelling observer

c is the speed of light, its value is 299,792,458 m/s

γ is the Lorentz factor


Question: Find the relativistic time, if time interval is 20 seconds and observer velocity is 20,000 km/s.


Given that

Time interval Δt = 20 seconds

Observer velocity v = 20,000 km/s


Relative time Δt' = Δt / √(1 - v²/c²)

= 20/√(1 - 20,000²/299,792,4582

= 26.84 sec

Therefore, the relative time is 26.84 seconds.

At Physicscalc.Com, you will discover various concepts calculators like acceleration, thermodynamics, electromagnetism and many more that assist you to make your calculations quickly and simply.

FAQ's on Time Dilation Calculator

1. Explain time dilation?

As per the theory of relativity, time dilation is defined as the difference between the elapsed time of the two events measured by either moving relative to each other located differently from gravitational masses.

2. At what speed does the time dilation become noticeable?

The time dilation becomes important at 1/10 of the speed of the light or 30,000 km/s.

3. How to calculate time dilation due to gravity?

The time dilation due to gravity can be calculated by using the formula Δt' = Δt x √(1 - 2MG/rc²). Substitute the values in the formula and solve to get the time interval affected by gravity.

4. What is the time dilation equation?

The time dilation formula is Δt' = Δt/√(1 - v²/c²). Here, c is the speed of light, v is the speed of the travelling observer, Δt is the time that has passed as measured by the stationary observer, Δt' is the relative time.