Single dosing means weighing each dose of beans rather than keeping a hopper full. Some grinders are built for it and some fight it.
Low retention
The defining requirement. If the grinder holds back 2 g and gives you 2 g of yesterday’s coffee, single dosing has achieved nothing.
Under 0.5 g is what a single-dose grinder should manage.
A short, steep path
Grounds should fall from the burrs to the exit in a straight line, with no horizontal runs, ledges or corners to hold them.
Long angled chutes are the enemy.
A removable or small hopper
Hoppers exist to feed beans by weight. Single dosing needs the beans loaded and gone, and a large empty hopper above the burrs simply causes static and popcorning.
Many single-dose grinders ship with a tiny bean funnel instead.
A bellows or blowback
A puff of air through the burr chamber after the dose pushes retained grounds out. Some grinders include one; some accept an aftermarket one.
What helps regardless
RDT — a drop of water on the beans. Kills static, dramatically cuts retention and clumping.
A dosing cup, metal, to catch the output and go straight to the portafilter.
Popcorning
With few beans and no weight above them, the last beans bounce on the burrs rather than feeding in.
Fixed by a weighted bean tube — a small metal cylinder that sits on the beans — or a grinder designed with a narrow throat.
Last reviewed 8 August 2026