Print this and check your mat
Ten true inches are 254 mm. Print this page at 100%, lay the strip along your grid, and you will know in ten seconds whether the mat you own has a real inch on it — ours included, when it arrives.
Before you print
Turn off “fit to page”, “shrink to fit” and “scale to fit”. Set the scale to 100% and the paper to A4. Almost every printer defaults to shrinking the page by a few percent, and a few percent is exactly the size of the error we are hunting.
Then check the ruler before you trust it. The first bar on the printout is 100 mm long. Measure that one first. If it does not read 100 mm, your printer scaled the page and nothing below it means anything — print again.
A tool that will not let you verify it is exactly the thing this page exists to warn you about.
The inch test
Printed at 100% on A4. Check the 100 mm bar first.
2 · Ten squares. End to end they are 254 mm
1 · First, check this bar reads 100 mm
If it reads anything else, your printer scaled the page. Print again with scaling off — do not try to correct for it in your head.
Lay this strip along your grid, starting at the middle of one printed line.
If ten of your squares end where the strip ends, your mat has a true inch.
If the strip runs past ten of your squares, your squares are smaller than an inch. Four millimetres of overrun means 25 mm squares.
One inch has been exactly 25.4 mm since 1959. Ten of them are 254 mm. A mat with 25 mm squares reads 250 — tidy, common, and not an inch.
Cloth and rubber settle a little once rolled and unrolled, so a millimetre either way is manufacturing. Four is not.
Why a mat can fail this
A 70 × 40 cm mat holds 27.56 inches along its long side. Not 27, not 28. So a maker has to choose: keep the inch and accept partial squares at the edge, or shrink the square until the number comes out round. 700 divided by 28 is exactly 25.0 mm, which is how a mat ends up advertised as “28 × 16 squares, 1 inch grid” while being neither.
The long version, with the arithmetic, is in what a 1-inch grid actually is.
And ours?
We do not know yet, and we are not going to guess. Our print file puts one inch every 195.072 pixels across 5376. The first sample arrived on 10 September 2026, but a physical measurement of ten squares has not been published yet. The target is 254 mm; the file alone cannot verify the dimensions after printing.
Until then this strip is the honest thing we can hand you: it works on the mat you already own, from anyone, including the ones we would rather you did not compare us to. The shop is here if you want one after that.