The youngest we have found anywhere is 3. The oldest minimum is 17. Between those the options change sharply at a few specific ages and not at all in between, which is why the answer to "can my child go karting" depends so much on the exact year.
We only build a page where the answer actually changes. An eleven-year-old has the same options as a ten-year-old, so making separate pages for both would waste your time and ours.
Nearly every circuit sets a minimum height alongside the minimum age, and both have to be met. An average eight-year-old in the UK is around 128cm, so a track requiring 130cm turns away a good proportion of them, and one requiring 140cm turns away nearly all. Each age page lists the height rules for that year, lowest first.
Our guide to karting with children explains the age tiers, what karts they would be in, and what to check before booking.