Hey there! Budgeting for a day in Barcelona really depends on your travel style. Here's a breakdown based on what I've learned from my own trip:
Budget Traveler (50-75 euros/day)
Mid-Range Traveler (75-150 euros/day)
Luxury Traveler (150+ euros/day)
Barcelona Card. This city pass gives you free admission to many attractions, discounts on others, and unlimited public transportation. If you plan on doing a lot of sightseeing, it can be a good deal. But do the math first to see if it makes sense for you.
Free Activities. There are plenty of free things to do in Barcelona, like wandering La Rambla, exploring the Gothic Quarter, or relaxing on Barceloneta Beach.
Beware of Tourist Traps. Barcelona has its fair share of tourist traps, especially around La Rambla. Do some research beforehand to avoid overpriced meals or tacky souvenirs.