Yes, you are fully permitted to take suitcases on the London Underground (the Tube) at no extra cost in 2026. Transport for London (TfL) rules allow up to three items of personal luggage per person. However, there are practical challenges to consider. Many older stations lack lifts or escalators, meaning you may have to carry your heavy bags up multiple flights of stairs. For 2026 travelers, it is highly recommended to use the Elizabeth Line or the "Step-Free" maps provided by TfL if you have large suitcases. During peak rush hours (07:30–09:30 and 16:30–18:30), the trains can be extremely crowded, making it difficult and socially awkward to board with bulky luggage. If you have multiple large bags, taking a taxi or the Heathrow Express is often worth the extra cost for the added comfort and lack of stairs.