There is no single age limit. Each kit carries its own recommended age, and the range starts at four.
Ages 5 and up: Beep Boop. No tools, and nothing complicated to assemble. These introduce cause and effect and simple logic through play: https://circuitmess.com/beep-boop
Ages 7 and up: Bit 2.0 and its expansions. Coding and games on a console with a straightforward build: https://circuitmess.com/stem-toys-for-kids
Ages 9 to 11 and up: the electronics kits. These use real components, and some involve soldering. We recommend an adult works alongside a child on the soldering steps: https://circuitmess.com/stem-for-teens
If you would rather avoid a soldering iron, Wheelson 2.0 needs no soldering, and the NASA Artemis Watch 2.0 arrives fully assembled with nothing to build at all.
The recommended age for a particular kit is listed in the FAQ section of its product page. If you tell us the child's age and what they are interested in, we will suggest something. Tell us here, or email [email protected].