1. Overview
The TheCharterBox Distance Calculator returns the sea distance between two ports along a realistic ocean route — through the canals (Suez, Panama, Kiel), around the major capes, and never across land. From that distance it derives the steaming time at a chosen speed, a weather-margin-adjusted sea-day figure, an optional ETA, and an optional bunker estimate. Built for brokers, operators, and charterers who need a quick, defensible distance before quoting a voyage.
The route and distance are computed by TheCharterBox’s own sea-routing engine; the steaming time, sea days, ETA, and bunkers are worked out instantly in your browser as you change speed or margin. No software to install, and no external routing subscription.
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Realistic Ocean Route
Distance follows the lane a ship would actually steam — through canals, around capes, never cutting across a landmass.
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Route Alternatives
Where a canal is in play, the long-way-round is offered too — Via Suez vs Cape of Good Hope, Via Panama vs Cape Horn.
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Steaming Time & Sea Days
Distance ÷ speed gives steaming time; a weather/sea margin grosses it up to a planning sea-day figure.
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ETA & Bunkers
Add a departure for an ETA, and a daily consumption for an estimated total bunker figure for the passage.
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Interactive Route Map
The route drawn on a world map with port, canal, and cape markers — pan, zoom, and Fit. No tiles, no API key.
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Save, Share & PDF
Save routes to your account, share a link that carries the full calculation, export a branded PDF.
2. Getting Started
Access the Calculator
Visit www.thecharterbox.com/distance-calculator/. No login required to use the calculator, see results, switch between route alternatives, share a link, or print.
Account Benefits
| Feature | Without Account | With Free Account |
|---|
| Use calculator & see results | ✅ | ✅ |
| Switch route alternatives | ✅ | ✅ |
| Share link | ✅ | ✅ |
| Print calculation | ✅ | ✅ |
| Save & load routes | — | ✅ |
| Export PDF | — | ✅ |
| Report an issue | — | ✅ |
Register free at www.thecharterbox.com/register/
The Card Flow
RouteVoyage ParametersResults
Work top to bottom: pick the From and To ports, set the speed and weather margin, optionally add a departure and a daily consumption — the Results card updates as you go.
3. Route
- Start typing in From Port — type a port name, its code, or a country. After two characters a dropdown lists up to ten matches, each showing the country and the port code; click one to set it.
- Do the same for To Port. Use the ⇅ Swap button between them to exchange From and To in one click.
- Optionally add a Via Port — an intermediate port the route must pass through. The route then runs From → Via → To as a single combined leg.
KEY CONCEPT: The port list is the NGA World Port Index — around 3,800 ports worldwide. If a port doesn’t appear by name, try its UN/LOCODE (five letters, e.g. NLRTM for Rotterdam) or its country.
NOTE: With a Via port set, the route is one combined leg and the canal/cape alternatives are not offered — alternatives are computed for direct From→To routes only. Clear the Via field and a direct route’s alternatives return.
4. Voyage Parameters
These turn the distance into a voyage. Only the speed is needed for the derived figures; everything else is optional.
| Field | Description | Typical |
|---|
| Speed (kn) | The vessel’s expected service speed — drives steaming time and everything derived from it | 10–15 kn |
| Weather / Sea Margin (%) | A percentage added to steaming time for weather, current, and hull fouling; folded into the sea-day figure | 5% (default) |
| Departure (optional) | A date and time — with a speed entered, the ETA appears in the Results | For ETA |
| Consumption (MT/day) (optional) | Daily bunker consumption — with a speed entered, an estimated total bunker figure appears | Vessel dependent |
NOTE: Without a speed you still get the distance, route description, and map — but no steaming time, sea days, ETA, or bunkers, because all four are derived from the speed.
5. Results
The Results card leads with the sea distance in large figures, then the route description (From → Via → To, plus the canals or capes the route uses), and a row of derived voyage figures.
KEY CONCEPT: Steaming time is the raw distance ÷ speed, with no margin. Sea days takes that and grosses it up by the weather/sea margin, expressed in days. The ETA and the estimated bunkers both use the margin-inclusive figure — so a higher margin pushes the ETA later and the bunkers up.
What each figure means
| Figure | How it is worked out |
|---|
| Sea distance | Nautical miles along the selected route, from the routing engine |
| Steaming time | Distance ÷ speed, shown as days and hours (e.g. 25d 14:49) — no margin |
| Sea days | Steaming time grossed up by the margin, in days; the “(incl. 5% margin)” note shows the margin applied |
| ETA | Departure plus the margin-inclusive time (shown only when a departure is entered) |
| Est. bunkers | Consumption × sea days (shown only when a consumption is entered) |
EXAMPLE: Suppose the Via Suez route returns 8,300 NM. At a speed of 13.5 kn with a 5% margin: steaming time = 8,300 ÷ 13.5 ≈ 615 h (25d 14:49); sea days = that plus 5% ≈ 26.9 d. Add a daily consumption of 28 MT/day and the estimated bunkers come to about 753 MT. Enter a departure date and the ETA fills in automatically.
A footnote under the figures states the method: estimated routing; distances are indicative and may differ from executed routes.
SERVICE NOTICE: The route comes from a live routing engine. If it can’t be reached for a moment, your inputs are kept and a Retry button appears in place of the result — wait a few seconds and click it. Speed, margin, departure, and consumption changes never hit the network; only changing a port fetches a new route.
6. Route Alternatives
When the direct route uses a canal, the calculator also works out the long-way-round and offers both as selectable chips above the route description:
| Direct route uses… | Alternative offered |
|---|
| Suez Canal | Via Cape of Good Hope (round the south of Africa) |
| Panama Canal | Via Cape Horn (round the south of South America) |
Each chip shows that option’s distance and sea days, so you can compare at a glance. Click a chip and the headline distance, the route description, the voyage figures, and the map all switch to that option.
TIP: The chips are the negotiation lever. The canal route is shorter in days but carries the toll; the cape route adds sea days and bunkers but no canal cost. The calculator gives you the distance and day difference instantly — weigh that against the canal dues for the fixture.
NOTE: A chip is labelled by the route actually taken — “Via Suez”, “Via Cape of Good Hope”, “Via Panama”, or “Via Cape Horn” — not by which canal was switched off. A route with no canal in play shows a single result and no chips.
7. Route Map
Below the figures, the selected route is drawn on an interactive world map — the line curves through the canals and around the capes, with markers for the From, Via, and To ports and labels for the named canals and capes it passes. Switching the route-alternative chip redraws the line.
Map Controls
- Drag to pan; use the mouse wheel, a pinch, or the + / − buttons to zoom.
- Click Fit to frame the whole route again after panning or zooming.
TIP: The map is fully self-contained — the world basemap and the route line are bundled with the calculator. There are no map tiles, no API key, and no third-party requests, so it loads quickly and works on a locked-down network.
8. Save, Load & Share
Saving (Logged-In Only)
- Click “Save” — the title pre-fills as “From → To” (e.g. Rotterdam → Singapore); edit it if you like.
- Click “Load” to list your saved routes, newest first; click one to restore every field and recompute, or the × to delete it.
NOTE: You can keep up to 50 saved routes per account. If you reach the limit, delete one to save another.
Share Link (Everyone)
Click “Share” to copy a link that carries the complete calculation — both ports, any Via port, and all the voyage parameters — inside the link itself. Anyone opening it sees your exact inputs and the calculator recomputes the same route for them; a banner notes it was loaded from a shared link. Nothing is stored on the server, and a tampered, oversized, or out-of-date link is ignored.
9. PDF & Print
NOTE: PDF export requires a free account. Print works for everyone.
PDF — a branded document with the route (From / Via / To with codes), the selected route’s sea distance and routing description, a route-alternatives table when more than one exists, the voyage parameters, and the derived voyage figures. It is built from the calculated result, not scraped from the page, so it always matches what you see. File: distance-[from]-[to]-[date].pdf
Print — click “Print” or Ctrl+P. The map is framed to show the whole route and the controls are hidden. Enable “Background graphics” for colours.
10. Glossary of Terms
Cape of Good HopeThe southern tip of Africa — the long-way-round alternative to the Suez Canal between Europe/the Mediterranean and Asia.
Cape HornThe southern tip of South America — the alternative to the Panama Canal between the Atlantic and the Pacific.
ETAEstimated Time of Arrival — the departure date/time plus the margin-inclusive steaming time.
Great CircleThe shortest path between two points on a sphere; long open-ocean legs of a route follow it.
Kiel CanalThe canal across northern Germany linking the North Sea and the Baltic Sea.
Knot (kn)One nautical mile per hour — the unit of a ship’s speed.
Nautical Mile (NM)The unit of sea distance — one minute of latitude, about 1.852 km.
Panama CanalThe canal across Panama linking the Atlantic and the Pacific.
Sea DaysSteaming time grossed up by the weather/sea margin, expressed in days — the figure used for ETA and bunkers.
Sea Margin / Weather MarginA percentage added to steaming time to allow for weather, current, and hull fouling.
Steaming TimeDistance divided by speed, before any margin is applied.
Suez CanalThe canal across Egypt linking the Mediterranean and the Red Sea.
UN/LOCODEThe United Nations five-letter code identifying a port or location (e.g. NLRTM, SGSIN).
Via PortAn optional intermediate port the route is required to pass through, splitting the voyage into two legs.
11. Frequently Asked Questions
Do I need an account to use the calculator?
No. Use the calculator, see results, switch route alternatives, share links, and print without logging in. To save and load routes, export a PDF, or report an issue — register for a free account.
How are the distances worked out?
Along a realistic ocean route — through the canals, around the major capes, and never across land — computed by TheCharterBox’s own sea-routing engine. They are professional estimates for quoting and planning, not the exact executed route.
Why are there two route options?
When the direct route uses a canal, the calculator also offers the long-way-round: Via Suez against Via Cape of Good Hope, and Via Panama against Via Cape Horn. Click a chip to compare distance and sea days; the headline figure, route description, and map all follow your choice.
What is the difference between “Steaming time” and “Sea days”?
Steaming time is distance ÷ speed, with no allowance. Sea days takes that and adds your weather/sea margin, shown in days. The ETA and the estimated bunkers both use the margin-inclusive figure.
I entered a speed but see no ETA. Why?
The ETA needs a departure date/time as well as a speed — add one in Voyage Parameters and it appears. The estimated bunkers work the same way: they need a consumption figure.
Can I make the route pass through a particular point?
Yes — add a Via port. The route then runs From → Via → To as one combined leg. Note that with a Via port set, the canal/cape alternatives aren’t offered; those are for direct routes only.
It says the routing service is temporarily unavailable.
The route is fetched from a live routing engine. If it can’t be reached for a moment, your inputs are kept and a Retry button appears — wait a few seconds and click it. Adjusting speed, margin, departure, or consumption never needs the network.
Does the map need an internet map service or an API key?
No. The map, the world basemap, and the route line are all bundled with the calculator — no tiles, no API key, and no third-party requests.
Which speed should I enter?
The vessel’s expected service speed for the voyage. The weather/sea margin is there to cover weather and current, so enter the calm-water service speed and let the margin gross it up.
Are the results binding figures?
No — they are professional estimates for quoting and planning. Confirm against your routing or voyage software and actual conditions before fixing.
Does it work on mobile?
Yes. Fully responsive for desktop, tablet, and mobile, including the route map.
How do I report a bug?
Logged-in users can use the “Report Issue” button (Bug / Feature Request / Other), or email
[email protected] with what you entered and what you expected.
