The X4 is the direct bus between Southampton and Portsmouth, run by First, and it is the slower but cheaper alternative to the train. The whole run takes about two hours, starting at Southampton Central Station and following the coast through Woolston, Locks Heath, Titchfield, Fareham and Portchester before it reaches The Hard in Portsmouth. For the towns strung out in between, which the fast train skips, it is often the only direct link.
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Most people riding end to end are weighing it against the train, which covers the same two cities in about an hour. The X4 wins on price and on reaching the smaller places along the way, while the train wins on speed, so the right choice depends on where you are actually going.
The essentials on the X4
| Parameter | Detail |
|---|---|
| Route | Southampton Central Station to The Hard Interchange, Portsmouth |
| Operator | First Bus (Portsmouth, Fareham and Gosport) |
| Runs through | Woolston, Locks Heath, Titchfield, Fareham, Portchester |
| Journey time | about 2 hours end to end |
| Frequency | roughly hourly, about every 30 minutes with the X3 and X5 |
| First bus | 07:55 from Southampton, 06:50 from Portsmouth |
| Last bus | 19:20 from Southampton, 18:10 from Portsmouth |
| Single fare | capped at £3 under the national cap |
| Ways to pay | contactless, First Bus App, cash |
| Updated | November 2026 |
Following the coast road
The X4 traces the coast between the two cities rather than taking the motorway, which is why it is slower than the train but passes through so many towns. The map shows the shape of the run.
Because it threads through Fareham and the Locks Heath area, the X4 is as much a link between those towns and the two cities as it is an end-to-end service.
The stops from Southampton to Portsmouth
Heading east, the bus leaves Southampton Central, crosses the Itchen and works along the coast through the Fareham towns before dropping into Portsmouth. These are the main timing points in order.
| No. | Stop | What is nearby |
|---|---|---|
| 1 | Southampton Central Station | trains and the city centre |
| 2 | Southampton WestQuay | the main shopping centre |
| 3 | Woolston | east of the Itchen |
| 4 | Sholing | Botley Road |
| 5 | Bursledon | near the station and the river |
| 6 | Park Gate | village centre |
| 7 | Locks Heath Centre | shopping centre |
| 8 | Titchfield | old village |
| 9 | Fareham Bus Station | Fareham town and railway station |
| 10 | Portchester Precinct | Portchester shops, castle nearby |
| 11 | Portsmouth International Port | cross-Channel and Isle of Wight ferries |
| 12 | Victoria Park | city centre and the Guildhall |
| 13 | The Hard Interchange | harbour, Dockyard, Gunwharf, Harbour station |
Back towards Southampton
Westbound the order simply reverses, leaving The Hard and heading back out past the port, through Portchester and Fareham, and along the coast to Southampton. The nearby landmarks are the same in each direction.
| No. | Stop | What is nearby |
|---|---|---|
| 1 | The Hard Interchange | harbour, ferries and the train |
| 2 | Victoria Park | city centre and the Guildhall |
| 3 | Portsmouth International Port | the ferry port |
| 4 | Portchester Precinct | Portchester shops |
| 5 | Fareham Bus Station | Fareham town and station |
| 6 | Titchfield | old village |
| 7 | Locks Heath Centre | shopping centre |
| 8 | Park Gate | village centre |
| 9 | Bursledon | near the river |
| 10 | Sholing | Botley Road |
| 11 | Woolston | east of the Itchen |
| 12 | Southampton WestQuay | the shopping centre |
| 13 | Southampton Central Station | trains and the city centre |
Times and frequency
The X4 runs through the day rather than early into the night, so it suits daytime trips more than late ones.
| Time of day | How often |
|---|---|
| Daytime, Monday to Saturday | roughly hourly on the X4 |
| Along the corridor with the X3 and X5 | about every 30 minutes |
| Evening and Sunday | reduced, check the app |
The first bus leaves Southampton Central at about 07:55 and the last at 19:20, while from The Hard in Portsmouth the first is about 06:50 and the last 18:10. A few early journeys start from Fareham rather than Southampton. Because the X4, X3 and X5 share much of the route, you can often catch whichever comes first for the middle part of the trip. For the exact minute at your stop, the First Bus App shows live times.
The fare on the X4
The X4 crosses from the Southampton area into Portsmouth, but the national cap keeps a single cheap wherever you board.
- A single, however far you go, is capped at £3 under the national fare cap, which runs to March 2027.
- Tapping a contactless card or phone on as you board and off as you leave lets First apply its daily cap, so several trips in a day cost no more than the cap.
- For the whole Southampton to Portsmouth run, a First network or day ticket in the First Bus App is the simplest buy, and the app shows the price for your exact journey.
- Older and disabled pass holders travel free off-peak with a valid concessionary pass.
For most single trips the £3 cap is all you need to think about, and the day ticket only pays off if you are hopping on and off several times.
How to pay on the X4
There is no ticket office on the bus, so you sort your fare as you get on. The options are:
- Tap a contactless card or phone on as you board and off again when you get off, because First uses Tap On Tap Off and the tap off is what triggers the daily cap.
- Buy in the First Bus App before you travel, which also carries the network and day tickets for the wider area.
- Pay the driver in cash as you board, with the fare ready where you can.
Whichever you pick, the ticket is bought on the bus or in the app, with nothing to collect beforehand.
Before you ride the X4
How long does the X4 take from Southampton to Portsmouth?
About two hours end to end. It is a slow, all-stops coastal route, so for the quickest door-to-door trip between the two city centres the train is faster at around an hour.
Is the X4 cheaper than the train?
Usually, yes. A bus single is capped at £3 under the national cap, while a train fare on the same route is higher, so the X4 trades time for a lower price.
How often does the X4 run?
Roughly hourly on its own, and about every 30 minutes along the shared stretch where it runs with the X3 and X5.
Where does the X4 start and end?
Southampton Central Station at one end and The Hard Interchange in Portsmouth at the other, with some early journeys starting from Fareham.
How much is a single on the X4?
No more than £3, however far you travel, because of the national single fare cap. A day of hopping on and off is covered by First’s daily cap or a day ticket.
Who runs the X4?
First Bus, under its Portsmouth, Fareham and Gosport operation, which also runs the X3 and X5 along the same corridor.
Portsmouth And put this guide together from First Bus timetable and ticket information together with the operator’s published route data. If you would rather take the train, our guide to the Southampton to Portsmouth train covers the faster option, and the X4 sits alongside the city’s other services in our guide to buses in Portsmouth. The route also passes Portsmouth International Port. Last updated: November 2026. Check live times in the First Bus App before you travel.
