Do United Kingdom passport holders need a visa to visit SI?

No visa needed. UK ordinary passport holders can visit Slovenia (a Schengen state) for tourism for up to 90 days in any 180-day period without a visa. British citizens holding an ordinary passport do not need a visa for short tourist visits to Slovenia. Slovenia is part of the Schengen area, so UK travellers may stay visa-free for up to 90 days within any rolling 180-day period; days spent in any other Schengen country count toward the same 90-day allowance. Your passport must have been issued less than 10 years before the date of entry and remain valid for at least 3 months after your planned departure from the Schengen area. As of 31 May 2026, no pre-travel authorisation is required, but the EU Entry/Exit System (EES) is being rolled out, which collects biometric data (fingerprints and a photo) at the border at no cost. ETIAS — a mandatory online travel authorisation costing EUR 20 — is officially scheduled to begin in the last quarter of 2026, after which most UK travellers will need it before departure; it is NOT yet in force. Overstaying the 90/180 limit can lead to fines, deportation, or an entry ban of up to three years.