Grinder Sizes Explained: Which One Fits Your Life
Grinders are sold by a single number — 50 mm, 55 mm, 63 mm — and that number is doing a lot of unexplained work. It is not the capacity, it is not the height, and it is a poor guide to whether the thing will actually live in your pocket.
Here is what the measurement means, what each size feels like in the hand, and the second number that matters more than the one on the label.
The number is the diameter
It is the width of the disc, measured across the top. Nothing else. It tells you how wide the grinding chamber is, and from that you can infer roughly how much fits in one go — but it says nothing about how tall the grinder is, and height is what decides whether it disappears into a pocket.
This catches people out constantly. A 50 mm four-piece with three chambers stacked up can be taller than a 63 mm two-piece. The narrow one looks smaller on a listing and is the more awkward object in a jacket.
Diameter is what a grinder is sold on. Height is what you actually carry.
What each size feels like
Around 40 mm — novelty and keyring size
Genuinely small. Holds enough for one, needs refilling constantly, and the narrow grip means you are turning it with fingertips rather than a whole hand. Fine as a spare or a curiosity; frustrating as your only grinder.
50 mm — the carry size
The most common size sold, and the one most people should own if it is going out of the house. Wide enough to grip with a full hand, small enough to forget about in a pocket. The grinder in The Courier is a full 50 mm, which is why that kit works as a travel set rather than a shrunken one.
55 to 56 mm — the quiet upgrade
Barely bigger on paper, noticeably better in the hand. The extra few millimetres give a meaningfully wider chamber and more grip to turn against. The Biscuit sits here at 56 mm, which is part of why it does not feel like a novelty despite looking like one.
63 to 65 mm — the desk size
This is a two-handed object that lives somewhere. The chamber is wide enough to do a full amount in one pass, and the extra width makes it easier to turn, not harder — more on that below. The Crank is 63 mm and The Stack is 65 mm. Neither is a pocket item and neither pretends to be.
Bigger is easier to turn, not harder
This one is counterintuitive enough that it changes people's minds.
A grinder is turned by gripping the outside edge. The wider that edge, the more leverage your hand has against the resistance inside. A 63 mm grinder gives you noticeably more mechanical advantage than a 40 mm one, so it takes less force from you even though it is doing more work.
If twisting is uncomfortable — arthritis, a weak grip, an old wrist injury — the instinct is to buy something small and light. That is backwards. Go wider, or skip the twist entirely with a crank handle.
Side by side
| Size | Fits a pocket | One-handed | Amount per grind | Best for |
|---|---|---|---|---|
| ~40 mm | Easily | Fingertips only | Small | Spare, keyring |
| 50 mm | Yes | Comfortably | Single session | Carrying |
| 55–56 mm | Just about | Comfortably | Generous | Everyday |
| 63–65 mm | No | Easiest of all | Full amount | Desk, home |
The second number nobody quotes
Height is rarely in the listing and it is what determines pocketability. As a rough guide:
- Two-piece — shortest. A lid and a chamber, nothing else.
- Three-piece — one chamber taller.
- Four-piece — tallest, because of the screen and the bottom chamber.
So the honest question is not "what size" but "what size and how many chambers". A 50 mm four-piece and a 63 mm two-piece can occupy very similar space in a bag while behaving completely differently. If you are unsure which chamber count you want, the two-piece versus four-piece comparison covers that side of it.
Shaped grinders play by different rules
A sphere, a burger or a pool ball cannot be judged on diameter alone. The Eight Ball is round in every direction, so a listed measurement describes a ball rather than a disc — it takes up more room in a pocket than a flat grinder of the same number, and it grips completely differently.
Judge a shaped grinder by picking it up, not by comparing its number to a disc.
So which size
- It leaves the house → 50 mm, and prefer fewer chambers for height.
- It stays on a desk → 63 mm or wider. There is no downside except pocketability, which you do not need.
- You want one grinder for everything → 55 mm. It is the honest compromise and the one people regret least.
- Grip or wrist strength is the issue → wider, not smaller. Or a crank.
Questions people ask
Does a bigger grinder grind finer?
No. Fineness comes from the teeth and from how long you turn. A bigger grinder holds more and takes less effort per turn; the result is the same texture.
How much does a 50 mm hold compared to a 63 mm?
Roughly a 60% larger chamber area at 63 mm, since area scales with the square of the diameter rather than in a straight line. That is why the jump from 50 mm to 63 mm feels bigger in use than the numbers suggest.
Is a 40 mm grinder worth buying?
As a second one, yes — for a bag or a car. As your only grinder, most people find themselves refilling it three times and wishing they had gone bigger.
Does size affect how easy it is to clean?
A little, and in your favour. Wider chambers are easier to get a brush into. Chamber count matters far more than diameter here.
What size are the grinders inside the kits?
Both The Courier and The Blueprint include a full 50 mm grinder rather than a smaller one dropped in to make the box cheaper. That is worth checking on any kit before you buy it.