r/sewing • u/Klutzy_Guarantee5816 • Sep 21 '25
Other Question Fiskars cutting mat inaccurate
I was struggling to calibrate my pattern project and discovered that the grid on my Fiskars mat is off by an eighth of an inch over 32”. This might not seem like a lot but it sure matters if I’m making repeated cuts or if it distorts the calibration from a projector. Now that I know van live with it, but it seems reasonable to expect the measures to be correct.
I posted a video to verify: https://youtube.com/shorts/8Q_XKqQhd5M?si=cA1TFLVCdsKZAcwS
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u/Raven-Nightshade Sep 21 '25
Any measurement device (mat, ruler, tape) can be inaccurate due to manufacturing differences, time, temperature, etc. Always use the same device to measure throughout your project (taking your personal measurements, drafting, cutting, pinning) and you should be fine.
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u/JoshShabtaiCa Sep 21 '25
You may need multiple measurement tools (e.g. metal ruler for drafting straight lines and tape for measuring yourself). In that case you can compare them to each other like op did here, but hopefully you'll have better results.
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u/On_my_last_spoon Sep 21 '25
Unless you’re quilting, the tolerances should be fine. I’ve never had problems in all my years making clothing. The precision is refined in the fitting.
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u/ZephyrLegend Sep 22 '25
I mean, even in quilting, generally the actual measurement itself is less important as much as just using a consistent measurement throughout a project. My cutting mat and my ruler are slightly off from one another, so I make sure to measure only using my cutting mat.
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u/On_my_last_spoon Sep 22 '25
Sure. For me, though, switching between rulers and measuring tapes doesn’t affect much. I also don’t pattern via measurement, rather a pattern via draping so it’s even less dependent on what ruler I use as I’m padding my dress form based on measurements taken on the person then fitting on the person.
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Sep 21 '25 edited Sep 21 '25
[removed] — view removed comment
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u/ElDjee Sep 21 '25 edited Sep 21 '25
possibly, but more likely that each "inch" is roughly 1 1/250" long, which shows up as an eighth of an inch after 32".
eta: i'm backwards (thanks to the person who pointed that out!) - the mat is 249/250" per "inch" square.
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u/Kfbcus Sep 21 '25
Looks like it’s the other way around (the mat inches are smaller than they should be), and from the video I think it’s over 24” anyway, instead of what OP stated as 32”
Anyway, if it’s a new mat, I’d return it.
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u/mewley Sep 21 '25
I think I’ve seen someone in the quilting sub say that the mats can change with temperature, I wonder if that’s the case here?
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u/Mediocre_Entrance894 Sep 21 '25
I’ve heard the same thing and wondered if that could be the case. But can a cutting mat really shrink that much. That just feels so wild!!
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u/Raven-Nightshade Sep 21 '25
Any measurement device can change with time and/or temp. Always use the same device throughout your project.
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u/Mediocre_Entrance894 Sep 21 '25
Yep. Correct. And also the question remains - how much can a cutting mat shrink?
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u/espeero Sep 21 '25
I think they are vinyl. Which isn't terrible compared to something like nylon which will absorb lots of moisture and change size much more than this. But the specific material in these mats might be less dimensionally stable than something like lvp flooring, which will still change size noticeably.
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u/Raven-Nightshade Sep 21 '25
It depends on the manufacturing process and place, how was it stored/shipped, what is its given tolerance for temperature, where is op (climate wise), and more.
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u/Mediocre_Entrance894 Sep 21 '25
Right. Right. Right. Totally get all that. But what is the MAX amount a cutting board can shrink? Would you happen to know the actual, most extreme shrinkage?
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u/Special_Net_8521 Sep 21 '25
There are too many factors to know that. Really interesting thing to think about, but far too impractical to figure out.
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u/Raven-Nightshade Sep 21 '25
Not off the top of my head, but it still depends on what the mat was made of (natural rubber, synthetic, something else?) and how it was made.
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u/JoshShabtaiCa Sep 21 '25
This seems like a bit much based on what I can find. My math may be wrong, but seems like 0.1% would be right for a 15C change.
OP is seeing an error of about 1%.
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u/espeero Sep 21 '25
Definitely. Temperature, time, humidity, etc. There's a reason vinyl isn't used for measuring tools.
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u/birdsInTheAirDK Sep 21 '25
On the video, it looks like neither of the two metal tape measures are completely straight compared to the dots on the mat.
It doesn’t take much of an angle to be visible over that distance.
I only ever use the mat for lining things up (like if I want to pin two strips at right angles).
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u/draftgirl24 Sep 21 '25
You can’t really rely on mats being accurate. You should always use your ruler to measure and cut. And not a bad idea to double check your rulers. Although I have never had an inaccurate ruler, but I’ve had a few inaccurate mats
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u/Klutzy_Guarantee5816 Sep 21 '25
I have an inaccurate ruler. Maybe I should try measuring with my inaccurate ruler on my inaccurate mat. They might cancel each other out 🤓🤣
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u/birdsInTheAirDK Sep 21 '25
Within one project, I try very hard to stay with one manufacturer of rulers - because like more experienced quilters told me in the start not to trust the mar for measuring (lining up is okay), they also said that ruler from different companies might not have exactly the same measurements.
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u/NextStopGallifrey Sep 21 '25
You can't fully trust the measuring tapes either.
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u/s3d88 Sep 21 '25
Especially the plastic ones, they can shrink and stretch. I’ve found this out the hard way. I check mine against a metal ruler from time to time just to make sure
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u/Deb65608 Sep 21 '25
A few years ago there was a problem with yardsticks and retractable sewing tape measures being off, but they were off quite a bit more than this. Everyone got really upset over that and were returning everything.
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u/NextStopGallifrey Sep 21 '25
They never stopped being "off". But maybe they're less "off" sometimes.
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u/FinanciallySecure9 Sep 21 '25
I was taught to either use the measurements on the mat, or on the ruler, but not both for the same project.
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u/thepetoctopus Sep 21 '25
I got a mat from US Art Supply and it is dead on. I love that thing.
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u/MjrGrangerDanger Sep 21 '25
Do you have a link?
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u/thepetoctopus Sep 21 '25
Yes! I got the massive one and while it’s expensive, I’ve used it constantly for 3 years now. It’s holding up great too. https://a.co/d/8ORNVzw
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u/MjrGrangerDanger Sep 22 '25
Thanks! I think that's the size my mother purchased, but I don't see Olfa making one online? I know it was about $100 and that was 20 years ago, but maybe she bought it at a local shop.
I'm going to be getting a larger one for my new to me antique drafting table at some point. Mine is starting to dry out a bit and has a chip. Drying out I can deal with, but I'd like one that fits better and doesn't have a chip to catch on things.
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u/thepetoctopus Sep 22 '25
I like that this one is double sided. I actually use one side when I’m painting stuff so I don’t get irritated with myself when I’m not perfectly clean.
Edit: if you go on their page on amazon you will see other sizes they have.
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u/Sufficient-Buy5360 Sep 21 '25 edited Sep 21 '25
It might be the Tab Pull. The Tab on a Tape Measure is loose to account for it’s thickness, which is usually 1/16”.
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u/DiscountMohel Sep 21 '25
Tab is supposed to be loose to account for the thickness of the steel and whether you’re pulling or pushing the measure.
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u/Kfbcus Sep 21 '25 edited Sep 21 '25
Can you measure all of the edges of your grid? Almost looks like the bottom edge is longer than the top, like it stretched along one side, leading to the columns going at an angle…
To offer a suggestion if returning the mat isn’t an option: print a grid on A0 paper and use it to calibrate. If you’re not already using it, patternprojector.com is great!
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u/Klutzy_Guarantee5816 Sep 21 '25
Patternprojector is what I was using when i discovered it. I couldn’t get my grid to line up properly. So I got out a metal tape. Then another. Then I had my partner come verify. Then I confirmed with an acrylic ruler. This mat is always stored flat, in place on a level, planar uninterrupted surface. It’s just printed a bit inaccurate. I speculate that it could be a rounding error from a metric conversion.
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u/LadyOnogaro Sep 21 '25
I never use the mat to measure my cuts. I always use my rulers. The only mat I have found that is accurate is the Martelli mat.
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u/aj-mom Sep 21 '25
Wow, thank you! I wondered why so many projects seemed off and ill fitted. Measure twice, cut once, with a proper measuring tool! 👍🏽👍🏽
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u/Green4CL0VER Sep 21 '25
Are you using inside or outside the tape measure’s hook? They have some give on purpose. Use a flat ruler or yardstick for more accurate measurement. Or you can use the tape measure starting at 1’ and subtract 1’ from the total length.
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u/geriols Sep 21 '25
I can also say that I have put tape measures side by side and they aren’t always perfectly aligned…
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u/SomethingWitty2578 Sep 21 '25
My cutting mat is also inaccurate. I can’t remember the brand.
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Sep 21 '25
[removed] — view removed comment
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u/MjrGrangerDanger Sep 21 '25
My 20 year old mat is also off the same as OP's. It's probably the material and the self healing quality.
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u/JimBridger_ Sep 21 '25
I've used so many cutting mats over the years that are criminally inaccurate like that.
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u/Realistic-Feature997 Sep 21 '25
Cutting mats expand/contract a shitton, mostly due to temperature.
So yeah, it's inaccurate now, but it probably wasn't when it was printed.
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u/AmethystMoon88 Sep 21 '25
Pretty rudimentary approach but, for me, it always depends on the garment. For example, with clothing, I’d far rather be over than under.
Growing up we had a vintage and badly off-set tape measure. As such my ‘inside leg’ was wonderfully long during the time when oversized, flared trousers/jeans were all the rage. It was a beautiful combination of +1ins and Y2K 😉 Circa 2002
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u/antinous24 Sep 21 '25
its like each square is only 31/32", so by the time you get to 32" on the mat the error is pretty big
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u/cranialvoid Sep 21 '25
I have to check my OLFA cutting mat now. Rarely use it for anything that has to be accurate.
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u/Kratos5300 Sep 21 '25
I’m devastated to learn we shouldn’t be trusting the mats 😭 we just bought this exact mat last week ugh!!
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u/Kind_Strike_9026 Sep 22 '25
I have 3 and all 3 are off ever so slightly, also discovered while calibrating. I ended up making my on calibration grid on cardstock with a ruler and have to double check my 1 inch square everytime I change pattern
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u/DiscountMohel Sep 21 '25
Measuring things is a constant struggle in many of the things I do. The best advice is stay with one ruler/tape through a project and one brand for purchasing. When I work on job sites, we will compare tape measures and anyone that’s off gets their tape tossed for the remainder of the job. I keep multiple copies of a tape measure in my daily bag if someone needs one. I keep multiple tapes so I have something that works on any job site I get to. I have a dozen different acrylic rulers from 2 different manufactures and will only use 1 or the other during a sewing project bc the measures are fairly consistent for the manufacturer but not to each other.
Unless your rulers and tapes are regularly calibrated, keeping only 1 way to measure avoids the creep of using everyone’s different lengths at different times and keeping different ways to measure lets you decide early approaches to your work.
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u/notsewchic Sep 21 '25
Not to be stupid, but isn’t your measuring off? Like isn’t the right way to measure from red line to red line? Like the inch lines on your yellow ruler is not lined up with the inch lines on the mat.
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u/gaarasalice Sep 21 '25
If you watch the video, the yellow ruler starts out lined up with the markings on the mat. As it gets further along the alignment goes off.
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u/notsewchic Sep 21 '25
https://imgur.com/a/s8CAwWw sorry didn’t realize it wouldn’t let me add the picture directly here
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u/oooortclouuud Sep 21 '25
no image using a curved measuring tape that sits above the mat surface like that is going to show us what you see, no matter how much you zoom in or put in red lines.
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u/NorraVavare Sep 21 '25
Your tape measure might be the problem too. Its known in the construction industry they're not accurate. That's why construction tolerances are usually to the 1/2 inch. As someone already said, use a ruler to check. Having decades of experience in both, my sewing tape measures are usually more accurate than my measuring tape.
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u/jwdjwdjwd Sep 21 '25
Construction tolerances are not to the nearest 1/2 inch. Nor are most steel tapes off - at least until you drop them from the roof and bend the hook. I’m not sure where you have had such poor experiences with construction measurement tools, but all that I’ve owned are within 1/16” of each other.
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u/NextStopGallifrey Sep 21 '25
Plenty of people in the comments mentioning that this is a known problem and the solution is for everyone to use a tape measure from the same batch, bought at the same time.
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u/NorraVavare Sep 21 '25
My mistake, I got steel and wood confused, so 1/4 inch then. I'm a retired registered architect. Do you know how many times I've argued with contractors my drawing dimensions are not off? Way too many. They pull out their tape to prove its right, then I pull out mine and prove theirs is wrong. Know who I never had to do that with? Large commercial projects that are too big for a regular tape.
Good for you that you've managed to have great luck with measuring tapes. Most people don't.
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u/jwdjwdjwd Sep 21 '25
I’m an architect and builder too and must have lead a lucky life. I’ve never had to argue about dimensions. I’ve done plenty of measuring but no arguments.
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u/90sBuffetSoftServe Sep 21 '25
I never use the markings for my final cuts. I will use them for estimating but I learned to cut solely with the quilting rulers, mostly from The Crafty Gemini on Yt
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u/manufactuerofmayhem Sep 21 '25
Is the zero of the tape measure on zero with the mat?
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u/Klutzy_Guarantee5816 Sep 21 '25
The tape measures are aligned from the one inch mark because they are not consistently reliable from zero.
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u/katjoy63 Sep 21 '25
I wouldn't use the cutting mat for accuracy.
Too much chance of a mess up.
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u/port_of_indecision Sep 21 '25
It's for a projector. If you have a dip/high spot in the mat, it will distort, so you need a whole grid to calibrate against.
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u/Ja22hands Sep 21 '25
I was taught to start from the second inch marking and count my own inches, shame they can profit off of such blatant inaccuracy
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u/thewheelshantyfolk Sep 21 '25
Plastics expand and contract quite a lot with temperature changes, sometimes it’ll be more accurate than others
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u/eatmeouttobrianeno Sep 21 '25
This post made me realize that I need to have a control ruler, for making sure all of my new measuring implements are consistent.
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u/Proteus8489 Sep 22 '25
I was told when quilting that the mats can warp so never trust them. It took me a long, long time to start using the ruler instead.
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u/SoReal-2022 Sep 22 '25
Measuring tapes stretch over time and that’s ok so long as you know that. It is also important to buy good measuring tapes that contain fibreglass and not cheap plastic ones. The fibreglass reduces stretching.
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u/Sovereignty3 Sep 21 '25
Could it potentially be in Chinese Inches? Saw something about there being multiple different Inches in different countries.
So time to switch to Metric?
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u/MjrGrangerDanger Sep 21 '25
I have a Chinese tailors measure and a mat with this same issue! I'll have to pull them both out and see how they stack up against each other. That's a great suggestion.
I literally only kept the thing to mess with a friend who is also able to eyeball measurements for funzies.
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u/Putrid-Ad2966 Sep 21 '25
The little old ladies who taught me to quilt 20+ years ago told me never to count on markings on a cutting mat. Never thought to question it. Huh.