Which size do I need. It is worth getting right before you order rather than after, because the two sizes are not close, and a cover that does not fit is not a cover.
Here is everything we know, including the numbers we used to keep to ourselves.
Start with the notebook, not the cover
An A5 notebook is 148 by 210 mm. An A6 notebook is 105 by 148 mm. Measure the book you already use — closed, at its widest point — and match it. Do not size up hoping the cover will grow into the notebook. It will not.
The measurements
These are the covers themselves, not the notebooks. Height stays the same whether the cover is open or closed.
- A5 standard — 220 mm tall, 350 mm wide open, closing to about 170 mm.
- A5 trifold — 220 mm tall, 450 mm wide open, closing to about 170 mm.
- A6 standard — 158 mm tall, 250 mm wide open, closing to about 120 mm.
- A6 trifold — 158 mm tall, 320 mm wide open, closing to about 120 mm.
Two things worth reading twice. About 5 mm goes into the fold itself, which is why the closed width is a little less than half the open one. And the trifold's closed width moves depending on how many notebooks are inside and how tightly it is wrapped — that number is a guide, not a promise.
The question that actually decides it
Not "how much do I write". Where does the notebook spend its day?
If it lives on a desk and gets opened flat while you work, A5. You will want the writing space and you will not be carrying it far. If it lives in a coat pocket, a bag, or your hand on the way somewhere, A6. It is the difference between a book you write in and a book you carry.
If neither number matches
Plenty of good notebooks are not A5 or A6. Field Notes, Hobonichi Weeks, half a dozen Japanese formats, and whatever you were given as a present.
Everything here is cut after the order comes in, so a non-standard size is the same work with different numbers — not a favour. Send the height, width and thickness in millimetres, measured closed, and how many notebooks you want to carry, on the custom size request page.
And if you are unsure between two sizes, write before ordering rather than after. We would rather answer an email than remake a cover.