Understand
How it works
The four sorting criteria, one by one: where the figures come from, what they are worth, and their limits.
Price
Every price shows its type. There are three, and they are never mixed.
| Type | Display | Source |
|---|---|---|
| Exact price | “€24.99” · Exact price · operator | Fare published by the network with its timetables |
| Official range | “€28–127” · Official SNCF range | Minimum and maximum prices published by SNCF as open data (TGV INOUI, OUIGO, Intercités). Not available yet: these fares are not imported yet. |
| Estimate | “≈ €27” · Estimate | Our model, below, when no source gives a price |
The price of a journey is the sum of the prices of its legs. It keeps the least certain type: a single estimated leg is enough for the total to be shown with “≈”.
A range is not today's price. To find it, every journey offers a link to the operator's website.
The estimation model
It is used as a last resort. Its values are reviewed every year.
| Type of transport | Median price | Range |
|---|---|---|
| High-speed (no SNCF fare found) | €0.12/km, minimum €12 | €0.05–0.26/km |
| Intercités (no fare found) | €0.10/km, minimum €8 | €0.05–0.16/km |
| TER | €0.12/km, minimum €2 | €0.07–0.18/km |
| RER, suburban train | €2.50 per ticket | €2–5 |
| Metro, tram, city bus | €2 per ticket | €1.50–2.50 |
| Intercity bus (15 km and over) | €2.50 per ticket | €1.50–6 |
| Long-distance coach (excluding BlaBlaCar) | €0.05/km, minimum €3 | €0.02–0.10/km |
| Ferry | €5 per ticket | €2–30 |
| On-demand transport | €3 per ticket | €2–6 |
In town, only one ticket is counted per network: metro, tram, RER, funicular and buses under 15 km share the same ticket.
Split tickets have their own page: how they work and the risks.
CO₂
For each leg, the distance travelled is multiplied by an emission factor that depends on the mode of transport. The journey's CO₂ is the sum of its legs.
| Mode | g CO₂e per passenger per km |
|---|---|
| High-speed train | 2.9 |
| Metro | 4 |
| Tram | 4 |
| Funicular, cable car | 5 |
| RER, suburban train | 6 |
| Intercités | 9 |
| TER | 25 |
| Coach | 30 |
| On-demand transport | 80 |
| Bus | 100 |
| Ferry | 120 |
| Plane | 225 |
These are orders of magnitude published by ADEME, the French environment agency (impactCO2), reviewed every year.
The comparison with the car assumes a petrol or diesel car with one person on board: 142 g CO₂e per km, over the straight-line distance multiplied by 1.25 to approximate the road distance. The difference (“−98% vs car”) is only shown if the journey emits less than the car.
Outside France (in Great Britain), one-go does not calculate CO₂: the French factors do not apply there.
Walking
This is the total time spent on foot: from the starting point to the first stop, during connections, and from the last stop to the destination. You set the maximum walking time accepted at departure and arrival in the search options (20 minutes by default).
Duration
It runs from the time you need to leave to the time you reach your destination: it therefore includes walking and waiting for connections, not just the time spent in vehicles.
Sorting
Journeys are ranked by the chosen criterion: price, duration, walking or CO₂.
In case of a tie, the shortest journey comes first (when sorting by duration: the one that arrives earliest); if the tie remains, the one that leaves earliest. A journey with a cancelled train always goes to the end of the list.
Real time
When a network publishes its delays and cancellations as open data, one-go shows them: a delay appears as soon as it reaches one minute (“+3 min”), and a cancellation is flagged on the journey.
Not all networks publish this information. Without it, the times shown are the scheduled times. In any case, check the traffic status with the operator before you leave.
The list of data used and their licences is on the Sources and licences page.