Belfast to London Sea Distance Calculator

Calculate the exact nautical distance from Belfast, United Kingdom to London, United Kingdom. Plan your maritime journey with our professional route calculator.

Distance
692.5 nm
nautical miles
Under Sail
5.8 days
at 5 knots
Under Power
2.9 days
at 10 knots
Best Time
May-September
Typical Sailing Season

Distance follows a sea-lane route. Sailing times are estimates at fixed cruising speeds and vary with vessel, weather, and currents.

Interactive Route Map

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Distance: 692.5 nautical miles
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This map shows the direct sea route from Belfast to London. The actual sailing path may vary based on weather conditions and navigation requirements.

Passage details

This is a markedly indirect coastal passage: the navigable route runs 146% longer than the 281 nm direct line, its heading turning from northeast to west.

Sea distance
692.5 nm (1282.4 km)
Direct line
281 nm146% longer
Great-circle bearing
129° (southeast)
Geographic extent
4.8° × 7.4°
Crossing
Domestic · Same region
From
Belfast (United Kingdom) 54.6167, -5.9000
To
London (United Kingdom) 51.5000, -0.0833
Route basis
Sea-lane route
Passage timeEstimated passage time by cruising speed
Cruising speedDuration
5 kn5.8 days
8 kn3.6 days
10 kn2.9 days
12 kn2.4 days

Distance follows a sea-lane route generated from marine traffic lanes; passage times are computed at fixed cruising speeds.

Read the methodology — How we calculate sea distances

Last reviewed 2026-06-17

About Belfast to London Route

A long open-water within one country sea route between Belfast and London, this passage between two major harbours in the Northern Europe region demands attention to tidal streams and seasonal ice in the higher latitudes.

The corridor between neighbouring ports of the same region joins Belfast, United Kingdom to London, United Kingdom.

Navigation Tips

  • •Plan this long open-water within one country leg in the Northern Europe region with attention to tidal streams and seasonal ice in the higher latitudes.
  • •Provisioning for this long open-water passage in Northern Europe should account for regional supply networks.
  • •Allow time for entry formalities on this within one country leg between neighbouring ports of the same region.
  • •Adapt safety equipment to Northern Europe conditions for this long open-water crossing.
  • •For a within one country crossing between neighbouring ports of the same region, ensure clearance papers and visas are in order before departure.

Suggested Stops

On a long 692.5 nm passage from Belfast to London, these ports make convenient places to break the journey, refuel, and rest.

  1. Rosslare (Ireland) · ≈173.1 nm in — View port details
  2. Portland Harbour (United Kingdom) · ≈449.3 nm in — View port details

Frequently Asked Questions

How far is it from Belfast to London by sea?

This is a long open-water sea passage of about 692.5 nautical miles between Belfast and London in Northern Europe.

How long does it take to sail from Belfast to London?

Average voyage time on this long open-water between neighbouring ports of the same region leg of 692.5 nautical miles is 2.9 days – 5.8 days.

What's the best time to sail from Belfast to London?

Aim for May-September for the calmest passage in Northern Europe; off-peak periods bring tidal streams and seasonal ice in the higher latitudes.

Plan Your Perfect Maritime Journey

Use our advanced calculator above to customize your route, add waypoints, calculate fuel costs, and share your journey plan with crew members.

Plan another route with our Sea Distance CalculatorNavigation Guide