Time Dilation Calculator

Distances are treated as stationary-observer distances. No length contraction is applied to the route distance. Times are rounded for storytelling use to years plus days.

Journey Profile Accelerate to target speed, cruise, then decelerate Accelerate to halfway point, then decelerate to destination

Trip

Total Distance (light-years):

Target Velocity + Cruise Mode

Target / Cruise Velocity (% of c):

Acceleration Distance (light-years):

Deceleration Distance (light-years):

Example: 20 ly total, 99% c, 1 ly acceleration, 1 ly deceleration gives an 18 ly cruise.

Halfway Acceleration Mode

Propulsion Drive Output (g):

Maximum Speed Limit (% of c, optional):

Leave blank for no speed limit. If entered, the ship accelerates to this speed, cruises, then decelerates. Uses real Earth gravity conversion: 1g ≈ 1.032295 ly/yr².