Trains do not have a passenger speedometer. You sit on a quiet coach watching countryside slide by, and there is no way to know whether you are doing 90 mph or 180 mph. A GPS speed test on your phone closes that gap in seconds. Open a webpage, place the phone near the window, and the true speed appears.
How a phone GPS works on a train
Your phone uses the same satellite-based GPS as any other GPS receiver. Speed is calculated from the Doppler shift in the satellite signals — not from comparing successive positions. The Doppler method gives accurate speed even when the position fix is rough, which is why trains can show clean speed readings even when the position dot drifts in low-signal areas.
For accuracy on a train, the key factor is window view. A clear window to open sky lets the phone see four or more satellites easily. A small window with high vegetation overhead drops the satellite count and increases noise. Double-decker upper-floor windows give the best reception; lower-floor windows the worst. Side seats outperform aisle seats.
The phone does not need to be touching the window — within a few centimeters is fine. Put the phone face-up on the fold-down tray or hold it loosely on your lap with the screen visible. The GPS antenna is inside the phone, near the top edge, so orientation does not matter much.
What you will see by train type
Different train categories run at very different speeds. Roughly:
- Metro / subway: 25 to 40 mph (40 to 65 kph) typical, dropping to walking pace in tight curves and through stations. Underground sections mean GPS dropout — only elevated lines and surface trains will register.
- Commuter rail: 60 to 90 mph (100 to 145 kph) on the main runs, dropping for stations and switches. Most US commuter rail averages 35 to 50 mph counting stops; the peak between stations is much higher.
- Intercity: 80 to 125 mph (130 to 200 kph) on conventional rail. Amtrak Acela hits 150 mph (240 kph) on its fastest sections in the Northeast Corridor. European intercity (UK East Coast Main Line, German ICE on conventional track) typically peaks at 125 mph.
- High-speed rail (HSR): 155 to 217 mph (250 to 350 kph). Japan Shinkansen, Germany ICE3, France TGV, Spain AVE, China CR400 Fuxing, South Korea KTX, Italy Frecciarossa. The fastest scheduled service is the CR400 at 217 mph between Beijing and Shanghai.
- Maglev: Shanghai Maglev operates at 268 mph (430 kph) on a 30 km airport link, the fastest scheduled passenger service of any kind. Japan SCMaglev (under construction) targets 314 mph (505 kph).
Tunnels and other dropouts
Tunnels block GPS completely. There is no workaround — satellite signals cannot penetrate even a thin layer of rock or concrete. Long tunnels mean minutes of no reading. The Channel Tunnel, Gotthard Base Tunnel (57 km), Seikan Tunnel (54 km), and the high-speed Tunnel de Saverne are common dropout zones for European and Japanese travelers.
The speed reading freezes on the last value before the tunnel entry and stays frozen until the train emerges. Some speedometer apps interpolate the gap from the last known speed; others show a stale value. Both behaviors are honest — the GPS has no signal to update from.
Deep railway cuttings, viaducts in tight gorges, and densely built urban canyons cause similar problems. The reading might show a wildly low value if only one or two satellites are visible. Wait for the train to emerge into open country and the reading stabilizes within a few seconds.
The fastest scheduled trains in the world
As of 2026, the production train speed leaderboard is:
- Shanghai Maglev: 268 mph / 430 kph (airport link, 30 km only)
- China CR400 Fuxing: 217 mph / 350 kph (Beijing-Shanghai, conventional steel-wheel)
- France TGV M: 200 mph / 320 kph (LGV Atlantique, Sud-Est, Méditerranée)
- Germany ICE 4 (and ICE 3 redux): 186 mph / 300 kph (Frankfurt-Cologne high-speed line)
- Spain AVE Talgo 350: 186 mph / 300 kph (Madrid-Barcelona, Madrid-Seville)
- Italy Frecciarossa 1000: 186 mph / 300 kph (Milan-Rome-Naples)
- Japan N700S Shinkansen: 177 mph / 285 kph (Tokaido and Sanyo lines)
- South Korea KTX-Sancheon: 187 mph / 300 kph (Seoul-Busan)
- UK Eurostar (e320): 186 mph / 300 kph (London-Paris, London-Brussels)
- USA Amtrak Acela: 150 mph / 240 kph (Boston-NYC-DC Northeast Corridor)
For all-time speed records (not scheduled service), a special- configuration French TGV reached 357 mph (574 kph) in 2007 on test runs. The L0 series maglev under construction in Japan has reached 374 mph (603 kph) in trials.
What the speedometer shows you
Open the live GPS speedometer on your phone while seated near a window on a moving train. You will see:
- The current speed in your selected unit (mph or kph)
- A live dial and digital readout that update every second
- An accuracy indicator — usually 1 to 3 mph on a train
Place the phone where you can see the screen, glance occasionally as you cross open country, and you have a real-time train speed test that needs no app and no permission beyond the one-time GPS access prompt.
Other tools you might want on the train
- MPH to KPH converter — if you are reading European train timetables or specs from a US perspective.
- KPH to MPH converter — for the reverse.
- Speed, distance, time calculator — for working out ETA from a measured average speed.
- Car speed test — the related tool for verifying a car speedometer.
- How a browser measures speed with GPS — the technical explainer.