A petty and a paring knife aren't the same tool, though plenty of people buy one expecting it to do the other's job. Simplest way I've found to explain it: the paring knife works in your hand, the petty works on the board. Once that clicks, choosing gets easy.

What a paring knife is for

Short. 75 to 100mm, and the shortness is the whole point. You're holding the food in one hand and the knife in the other, and the blade is working toward your thumb. Peeling an apple in one long strip. Hulling strawberries. Coring a tomato. Digging eyes out of a potato. Segmenting an orange over a bowl.

None of that happens on a cutting board. The knife's a precision tool for in-hand work, and once a blade gets past about 100mm it starts feeling like a liability when the point is aimed at your palm.

Japanese makers do make paring knives. It's not really a traditional Japanese shape though. In a Japanese kitchen most of this work gets done with a petty on the board, or with a little single-bevel ajikiri if fish is involved.

What a petty is for

The name comes from the French petit, via Japanese (ペティナイフ). 120 to 150mm usually, sometimes 180. Shaped like a gyuto that's been shrunk: a little belly, a pointed tip, enough height to clear your knuckles if you choke up on it, though not a lot.

It's a board knife. Shallots, garlic, one carrot, trimming a chicken thigh, cutting a lime into wedges, a handful of mushrooms when getting the big knife out feels like overkill. Cooks in restaurants use them constantly for the small stuff because they're quicker to grab than a 240 and more precise on little things.

Can a 150 petty do paring-knife jobs? Sort of. Hold it near the heel and you can peel with it. It won't take an apple skin off in one strip as comfortably, and coring with a 150 feels awkward. It'll do in a pinch.

Which one you actually need

If you own a gyuto or a santoku and you're asking what the second knife should be, it's a petty. 135 or 150mm. It covers more ground than a paring knife and it's the one that'll get used every single day. A 120 is a reasonable compromise if you do a lot of in-hand work; short enough to peel, long enough for a shallot.

Go with a paring knife instead if your small-knife work is mostly fruit, mostly in hand, mostly done standing at the sink. And in that case, honestly, a cheap one is fine. A $10 Victorinox peels an apple about as well as a $120 Japanese paring knife, because the job doesn't ask much and a thin hard Japanese edge brings nothing to it that a soft easily-sharpened one doesn't.

Both, if you cook a lot. They're not redundant. But if the budget only stretches to one good knife, make it the petty.

Sizing a petty

120mm is the in-hand compromise. Fruit, garlic, small prep. A bit too short to feel like a real board knife.

135mm is what I'd point most people at. Enough length for a shallot or a chicken thigh and still nimble.

150mm is the pro favourite. Starts to overlap with a small gyuto, and if you've already got a 210, a 150 petty is the natural partner.

180mm is really a small gyuto or a short sujihiki wearing a different name. Only makes sense if you want one knife for everything and your board is tiny.

What to look for

Height matters more than you'd think. A very low petty, under about 28mm at the heel, gives you almost no knuckle room, so you end up pinch-gripping with your fingers curled up off the board. Some people like that. I find 30 to 32mm at the heel is the sweet spot on a 150.

Steel: whatever your main knife is, basically. A petty sees a lot of acid (citrus, tomatoes) so stainless makes life easier. VG-10, AUS-8, Ginsan, all fine. A carbon petty is lovely to sharpen and will go dark the first time it meets a lemon, which some of us consider a feature.

Handle: a wa handle keeps a petty light and quick, which suits the work. A Western yo handle makes it feel more like a small chef's knife. The handles page goes through the tradeoffs.

If you want to see what the knife's actually for before you buy one, the how to use a petty page walks through the grips and cuts.

Andrew Kuzmin · Editor-in-Chief, Okami Blades