Time & Date · Travel & Distance
Light Travel Time Calculator
Calculate how long light, radio signals or any electromagnetic wave take to travel a distance — Earth to Moon, Sun to Earth, to Mars or to nearby stars — at exactly 299,792,458 metres per second.
A ready-made version of the Speed, Distance & Time Calculator.
Your inputs
Quick start — try a typical case
Your result Live
Travel Time
8 min 19 s
1 AU at 1 c
- Time in Hours
- 0.138612
- Pace per km
- < 0:01 min/km
- Pace per mile
- < 0:01 min/mile
How this is calculated
Speed = Distance ÷ Time · Time = Distance ÷ Speed · Distance = Speed × Time · Pace = Time ÷ Distance
- Units
- Converted through metres and seconds using exact definitions (1 mi = 1,609.344 m; 1 knot = 1,852 m/h)
- Pace
- Minutes per km or per mile — the inverse of speed, used by runners
Speed, distance and time are linked by one formula: distance = speed × time. Give any two and the third follows. The calculator converts everything through metres and seconds, so you can mix units — a 350 km drive at 70 mph, or a 10 km run at 5:30 per km. Stops are added to the travel time, and the average speed including stops shows the realistic pace of a trip.
Assumptions & sources
- Speed is an average over the whole distance.
- Arrival time assumes departure and arrival in the same time zone.
- 1The International System of Units (SI Brochure) — BIPM
- 2Athletic Records and Human Endurance (Riegel, 1981) — American Scientist
Calculator ID TRV-SDT-001/light · version 1.0.0
Common questions
How fast is light?
Exactly 299,792,458 metres per second in a vacuum — the metre is defined from it. That's about 300,000 km every second.
How long does sunlight take to reach Earth?
About 8 minutes 19 seconds over the average distance of 1 astronomical unit (149,597,870.7 km).