Retention

The amount of ground coffee trapped inside the grinder — in the burrs, the chute, the spout — after a grind cycle. Measured in grams; reported as the difference between weigh-in and weigh-out.

Why it matters — High retention (0.5 g+) means today's first dose is partly yesterday's coffee. It also means your weigh-in doesn't equal your weigh-out — making consistent dosing harder.

Good to know

• Low-retention grinders (Niche, DF64, Lagom Mini, some Eureka models) are the modern standard. Designed retention of 0.1–0.3 g is normal.
• High retention on older commercial grinders is one reason single-dose grinders became popular for home use.