Port to Port Distance Calculator

How to calculate port to port distance

1. Choose the departure port. Search the list of over 5,000 seaports by the port’s English name, its country or its UN/LOCODE.
2. Choose the destination port. The calculator finds a route on water automatically and shows it on the map, with the distance in nautical miles (NM) and kilometers.
3. Enter your ship’s speed to see the time at sea. The ⇄ (swap) button reverses the voyage, Share gives a link to the same route, and New route starts again.

The tool is free and works in your web browser on a mobile phone or a desktop computer: there is no software to download and no sign-up.

How the route is built

The calculator asks our route service for a line that stays on water between the two ports and measures its length. One nautical mile is exactly 1,852 meters, so the distance in kilometers is the distance in nautical miles × 1.852.

• Ports. The marker of each port stands at its published position from the NGA World Port Index (Pub. 150) or, for a few ports, from NGA Pub. 151. The line starts at a calculation point on the water near that position, such as a harbor approach or a container terminal; a dashed line on the map joins the two.
• Ocean legs. Between the port approaches, the line follows a worldwide network of shipping lanes (MARNET) and goes through the Panama, Suez or Kiel Canal when the network’s shortest route uses it. The result names the canal.
• Coasts. Land and water come from OpenStreetMap and Overture Maps data. Near the United States, NOAA nautical charts and the U.S. Army Corps of Engineers inland charts are used as well.

Route distance and straight-line distance

The shortest line over the globe between two ports, the great-circle distance, often crosses land. A ship has to go around coasts, islands and capes and through canals, so the distance along its route is longer than the direct distance. That is why the distance is measured along a route on water, not with a ruler on a map.

Transit time, ETA and fuel

Next to the distance, the calculator shows the days at sea for a container ship at a steady speed: hours = distance in nautical miles ÷ speed in knots. The speed starts at 14 knots as an example; enter your vessel’s own service speed, from 1 to 40 knots. Add the time at sea to the departure time for a rough ETA, the time the ship would arrive at the destination port. Time in port, canal and anchorage waiting, pilotage, currents and weather are not included.

For a first bunker estimate, multiply the days at sea by your vessel’s daily fuel consumption at that speed. The calculator does not estimate bunker consumption itself.

How accurate is the distance?

When Distances Between Ports (NGA Pub. 151, 2001) lists the pair of ports by the same canals, the calculator shows the book’s distance next to ours and the difference in percent. We checked the calculator against 5,095 port pairs listed in the book: the median route is about 2% longer than the book’s figure, and 98% of routes are within 20% of it.

The two figures can differ: the book measures between its own reference points along tracks chosen by navigators, while our line follows a lane network from a calculation point near each port.

Limits

• The distance is for voyage planning, not passage planning. It is not certified for navigation, and the calculator gives no waypoints.
• Water on the map is not known depth. The calculator does not check a vessel’s draft, air draft, length or beam against channels, bridges, locks and canals.
• Traffic separation schemes, pilot stations, emission control areas (ECAs), piracy high-risk areas, ice, seasonal routes and weather are not modeled.
• The calculator shows one route. It has no option yet to avoid a canal or to compare alternative routes.
• When we cannot confirm a water approach to a port or find a water route between two ports, the calculator says so and shows no distance.

Questions

Is the calculator free?

Yes. It needs no account, and a shared link opens the same two ports for anyone you send it to.

Can Google Maps or Google Earth measure a voyage?

They measure the distance of a straight line or of a path you draw by hand. They do not find a route on water around land, so they are not a sea route calculator.

Does it account for canals and vessel size?

Canals, yes: for example, Rotterdam to Singapore goes through the Suez Canal instead of sailing around Africa, and the result says so. Vessel size, no: draft, beam, length and air draft are not checked.

Does it track ships or use AIS data?

No. It measures a route between two ports; it does not use AIS positions or real-time ship data.

Planning a boat trip from a marina or any point on the water? Use the trip planning tools on the All Boat Calculators page.

Data sources

Map © OpenStreetMap contributors, © OpenMapTiles, OpenFreeMap. Routes and ports: MARNET shipping lanes (Eurostat SeaRoute), OpenStreetMap, Overture Maps, NOAA and U.S. Army Corps of Engineers chart data, GEBCO and GMRT depths, NGA World Port Index and Pub. 151, UN/LOCODE and the SMDG terminal list. The full list with licenses is on our About page. Not for navigation; no data provider endorses BoatCalculators.