Time to Go (TTG)

The estimated time remaining before a vessel reaches a selected waypoint or destination.

Often abbreviated to TTG, it is calculated from the remaining distance and an assumed or measured rate of closing. Navigation equipment may update the value continuously using speed made good towards the selected point rather than total speed over the ground.

The estimate changes with course, speed, current, manoeuvres and the waypoint selected. It should therefore be treated as a planning aid, not a fixed arrival promise, and the navigator should confirm that the equipment is using the intended route and destination.