Building sets worth keeping.

Many brick systems share a similar stud size, but fit and grip vary by brand, and LEGO doesn’t promise compatibility with other makers. Magnetic tiles and Plus-Plus pieces are separate systems and don’t connect to bricks.

It’s a rough guide. Technic sets with gears and pins often take longer than a play set with a similar count, so read the maker’s age label too and choose a set close to the last one the builder finished.

Use the Age filter. DUPLO and large magnetic tiles are made for small hands, while standard LEGO bricks are small parts and carry the maker’s choking warning for children under 3.