If you're clearing out a playroom with kids of different ages, there's a good chance you've got both Duplo and regular LEGO mixed together. Here's how to tell them apart, and why it matters when you're selling.
The size difference
Duplo bricks are designed for toddlers — they're roughly twice the size of a standard LEGO brick in every dimension, with bigger, rounder studs that are easier for small hands to grip and impossible to swallow. Regular LEGO bricks are the smaller, more detailed pieces used in most sets aimed at older children and adults.
Why they don't mix
Because of the size and stud-spacing difference, Duplo and regular LEGO pieces don't click together. They're really two separate systems that happen to share a parent brand — which is also why they're bought separately.
Why it matters for selling
We only buy genuine Duplo, priced by weight. If your collection includes both, it's worth a quick sort before sending — put the Duplo in one bag and keep any regular LEGO aside, since it can't be included in a Duplo offer and won't be paid for or returned if mixed in.
Got a pile of regular-size LEGO sets from an older child too? Our sister site BrickBuy buys those separately — sealed, built, or loose.