Open data

What the euro column is built on

The app has to answer a question NMBS does not publish an API for: what does this journey cost. It works it out from two published files, both served from this site, both baked into the app so a first launch with no signal still prices correctly.

These prices are indicative. They are the public grid for a second class single. The ticket you actually buy can differ: a supplement, a product you already hold, or a journey through Brussels Airport all move the number.

The files

/fares/latest.json — the version pointer. Names the current edition of each dataset, its path, its size and its SHA-256. Fetch this first; it is under half a kilobyte.
/fares/nmbs-fares-2025-10-15.json — the price grid, edition 2025-10-15.
/fares/rail-graph-2026-09-01.json — the rail network as a weighted graph, 2026-09-01.

Versioned files never change under their own name, so they cache forever. Only latest.json moves.

The price grid

Parsed from the NMBS tariff document, edition 2025-10-15. The charged distance is a tariff kilometre, the minimum is 3 km, and everything from 116 km up is charged as 118 km. It is not a rate per kilometre: the grid starts around €1.45 before the first kilometre is counted, which is why a plain euro-per-kilometre model underprices a commuter journey by about a third.

Distance	Anytime	With Train+	Off-peak, Train+	Weekend
1–3	2.50	2.50	2.50	2.50
4	2.50	2.50	2.50	2.50
5	2.50	2.50	2.50	2.50
6	2.50	2.50	2.50	2.50
7	2.60	2.60	2.50	2.50
8	2.70	2.70	2.50	2.50
9	2.90	2.90	2.50	2.50
10	3.10	3.10	2.50	2.50
11	3.20	3.20	2.50	2.50
12	3.40	3.40	2.50	2.50
13	3.60	3.60	2.50	2.50
14	3.70	3.70	2.50	2.60
15	3.90	3.90	2.50	2.70
16	4.10	4.10	2.50	2.80
17	4.20	4.20	2.50	3.00
18	4.40	4.40	2.60	3.10
19	4.60	4.60	2.70	3.20
20	4.70	4.70	2.80	3.30
21	4.90	4.90	2.90	3.40
22	5.10	5.10	3.00	3.50
23	5.20	5.20	3.10	3.70
24	5.40	5.40	3.20	3.80
25	5.50	5.50	3.30	3.90
26	5.70	5.70	3.40	4.00
27	5.90	5.90	3.50	4.10
28	6.00	6.00	3.60	4.20
29	6.20	6.20	3.70	4.30
30	6.40	6.40	3.80	4.50
31–33	6.70	6.70	4.00	4.70
34–36	7.20	7.20	4.30	5.00
37–39	7.70	7.70	4.60	5.40
40–42	8.20	8.20	4.90	5.70
43–45	8.70	8.70	5.20	6.10
46–48	9.20	9.20	5.50	6.40
49–51	9.70	9.70	5.80	6.80
52–54	10.20	10.20	6.10	7.10
55–57	10.70	10.70	6.40	7.50
58–60	11.20	11.20	6.70	7.80
61–65	11.80	11.80	7.10	8.30
66–70	12.60	12.60	7.60	8.90
71–75	13.50	13.50	8.10	9.40
76–80	14.30	14.00	8.60	10.00
81–85	15.10	14.00	9.10	10.60
86–90	15.90	14.00	9.60	11.20
91–95	16.80	14.00	10.10	11.70
96–100	17.60	14.00	10.60	12.30
101–105	18.40	14.00	11.10	12.90
106–110	19.30	14.00	11.60	13.50
111–115	20.10	14.00	12.00	14.10
116+	20.90	14.00	12.50	14.60

The rail network

Belgian line sections from Infrabel, with the kilometre posts at each end, turned into a graph: nodes are operational points and the stations spliced into the middle of a section, and every edge is metres along the track. The app runs a shortest path across it to propose the rail kilometres between two stations, which is a proposal on an editable field and never a silent input. NMBS charges an administrative tariff distance that can differ from the track, by a kilometre on an open corridor and by rather more around the Brussels junctions.

Where it comes from

Prices: NMBS/SNCB Tarieven, editie 2025-10-15.
Network: Infrabel Open Data, line sections and operational points.
Stations: iRail.

Neither file contains anything personal and neither needs a key. The app fetches them over plain HTTPS and sends nothing with the request.