BoatCalculators is an independent project by a small team that builds free trip-planning tools for boaters. Our goal is simple: help you estimate how far, how long and how much fuel a trip on the water will take, in a few clicks and without signing up.
What you can do here
- Sea Distance Calculator – distance by water between two places, in nautical miles, statute miles and kilometers.
- Boat Travel Time Calculator – underway time for the distance and cruising speed you choose.
- Boat Fuel Calculator – fuel needed and trip cost from your boat’s burn rate.
- Boat Routes – popular boat trips in Florida and to the Bahamas.
- Hull Speed, Propeller Slip, 2-Stroke Oil Mix and Boat Loan calculators, plus knots to mph and nautical miles to miles converters.
How the calculators work
When you pick two places, the calculator either computes a route over water on our routing network, including major canals and straits where needed, or shows a pre-computed route stored for a listed port pair. The distance of a computed route is the sum of its legs, each measured with the Haversine (great-circle) formula. Travel time is distance divided by your cruising speed, and fuel is travel time multiplied by your fuel burn rate. If you already know the distance, you can enter it directly.
Place search covers more than 5,000 ports and marinas: our own catalog plus marina locations from OpenStreetMap.
Planning, not navigation
Our results are estimates for trip planning. They are not navigation charts. A computed line can pass closer to land, shoals or restricted areas than a safe course; it uses depth data only in some waters and does not account for tides, currents, weather, traffic or local rules. Always use official nautical charts, current marine forecasts and local knowledge when you navigate.
Data and credits
The map, the positions of places in search and the routes on this site use data from these sources:
- OpenStreetMap – the map, place positions and route calculation. © OpenStreetMap contributors, available under the Open Database License.
- OpenMapTiles – the map style: © OpenMapTiles. Map tiles are served by OpenFreeMap.
- NOAA electronic navigational charts (NOAA Office of Coast Survey) – depths, channels, bridges and some harbor positions in Florida waters.
- GEBCO – depths in some waters outside NOAA chart coverage, such as around the Bahamas and in the Caspian Sea. GEBCO Compilation Group (2025) GEBCO 2025 Grid (doi:10.5285/37c52e96-24ea-67ce-e063-7086abc05f29).
- The U.S. National Waterway Network (U.S. Army Corps of Engineers and Bureau of Transportation Statistics) and Natural Earth – waterway lines and land outlines used for routes.
- Overture Maps Foundation – water and land outlines for port-to-port routes: © OpenStreetMap contributors, Overture Maps Foundation, available under the Open Database License.
- MARNET (EUPL-1.2) – the shipping lanes of port-to-port routes, adapted (modified in 2026) from Eurostat’s SeaRoute; MARNET is itself based on the Global Shipping Lane Network (2000) of Oak Ridge National Laboratory.
- U.S. National Geospatial-Intelligence Agency (NGA) – port positions and names from the World Port Index (Pub. 150), and book distances for comparison from Distances Between Ports (Pub. 151, 11th edition, 2001).
- UN/LOCODE, United Nations Economic Commission for Europe (UNECE) – port codes.
- The SMDG Terminal Code List – terminal positions for some port approaches.
- U.S. Army Corps of Engineers Inland Electronic Navigational Charts – channels and locks on U.S. inland waterways.
- GMRT – depths in some waters: Global Multi-Resolution Topography synthesis (Ryan et al., 2009, doi:10.1029/2008GC002332), CC BY 4.0.
None of these providers endorses BoatCalculators, and routes built from their data are not official charts.
Hull speed, propeller slip, oil mix and loan pages use standard published formulas, which we explain on each page.
Found a mistake?
If a distance looks wrong or a route crosses land, please tell us the two places and the speed you used. We review every report. Write to [email protected] or see our contact page.