How the ETA formula works
Example: a passage of 480 NM at 12 knots takes 40 hours (1 day 16 hours). Add that duration to the departure timestamp to get the ETA.
Frequently asked questions
How is vessel ETA calculated?
ETA is calculated by dividing the voyage distance in nautical miles by the vessel's speed in knots. The resulting travel time in hours is added to the departure date and time to produce the estimated arrival.
What is a nautical mile?
A nautical mile equals 1,852 metres, or roughly 1.15 statute miles. It is the standard unit of distance in marine and air navigation.
What is a knot?
A knot is one nautical mile per hour. A vessel steaming at 12 knots covers 12 nautical miles every hour.
How do I find the speed required to meet a target arrival?
Divide the total voyage distance by the target travel time in hours. The Required Speed tab does this automatically.
Do the results account for currents, weather or port turnaround?
No. The calculator assumes a constant speed over ground and no waiting time. Always add a suitable weather margin.
Related guide
Read Understanding Vessel ETA: A Practical Guide for the full ETA methodology, common slippage causes, and how to publish a defensible arrival window.