The short answer
Sagrada Família doesn't run its own bag storage, and there's no metro- or rail-operated locker at the site either. The practical answer sits a few minutes' walk away, on or just off Avinguda Gaudí: either an automated self-service locker shop or one of the shop-counter points Radical Storage lists along the promenade.
According to several storage guides, there's no train station at Sagrada Família itself, and the nearest one with an official left-luggage desk is Barcelona Sants, reportedly about ten minutes away by metro line 5. That's described as too much of a detour for a same-day visit, not a genuine nearby option — none of the operators covering this neighbourhood treat it as the sensible first stop.
Why the basilica can't help
There's no general cloakroom inside Sagrada Família for suitcases or day bags. One storage guide reports that small lockers are only available on-site to visitors holding a ticket for the towers, and only for backpacks — arrive with a rolling case and it won't get past the door with you. The same source suggests bags and rucksacks may be checked at entry generally, though this hasn't been independently confirmed. Either way, it's worth planning to arrive without excess luggage rather than hoping to sort it out on the day.
Two kinds of storage
A handful of automated locker facilities operate within a few minutes of the basilica — Luggage Storage Vault, Stow Your Bags and Locker in the City among them. These are self-service: a QR code or PIN, no counter, no shop hours to work around. Luggage Storage Vault in particular is monitored around the clock by the same private security firm that protects Sagrada Família itself, and includes a small key-sized locker for a phone or passport alongside the standard sizes.
The alternative is a shop-network app — Radical Storage, Nannybag, Bounce, Stasher — which books a bag into an ordinary local business rather than a dedicated locker: a supermarket, a shop counter, a tobacconist. The bag is fine, but the opening hours are whatever that shop keeps, not a guaranteed round-the-clock service, whatever the app's homepage implies.
What it actually costs
Automated lockers charge per locker, by the hour with a daily cap. Shop-network apps charge per bag per day instead — which matters once there's more than one case, since two people travelling with two bags each can end up paying more through a per-bag app than through a single locker sized to fit everything.
Hours worth checking twice
Shop-counter points follow retail hours, and those hours vary more around Sagrada Família than a quick glance at an app suggests. One Radical Storage listing on Av. de Gaudí is shown as open around the clock; walk a little further along the same street and its neighbouring listing closes entirely on Saturdays. The point named for the Sagrada Família metro station keeps a split weekday schedule — mornings and early evenings only — and shuts on Sundays, despite a name that implies a transit-authority locker rather than a shop with its own till hours.
Is it worth booking ahead
Booking mainly locks in a specific address and its hours rather than a scarce spot — none of the operators' own data suggests these points fill up. Cancellation is free across the major apps, so there's little to lose by reserving once travel plans firm up. The real value here is confirming, before the walk over, that the point you're heading to is actually open when you arrive, given how much that varies door to door on the same street.
