Santoku Knife Sizes Explained: 12cm, 13cm and 18cm Blades

Quick answer

For most home cooks, an 18cm santoku is the most versatile all-rounder, while a 12cm or 13cm santoku is better for small hands, tight prep spaces and quick vegetable tasks. Choose the smaller blade only if you rarely cut large items; otherwise start with the 18cm.

How to choose your santoku size in four steps

1. Measure your most common cutting task: Look at the largest item you prep regularly—a whole cabbage, a bunch of carrots, or a single onion. If it often exceeds 10cm in height or width, lean toward an 18cm blade. A common mistake is choosing a small knife for occasional large jobs, which forces awkward sawing. Write down the single largest ingredient you cut each week; that size sets your minimum blade length.
2. Try the grip before you commit: Hold the knife with your index finger and thumb pinching the blade just ahead of the handle. A 12cm or 13cm santoku should feel balanced and leave your wrist relaxed. If your hand feels cramped or the blade tips forward, size up. Checkpoint: you should be able to make a loose fist around the handle without your fingers overlapping the blade. If you cannot pinch the blade comfortably, the knife is too short for your hand.
3. Match the blade to your board and storage: A 12cm or 13cm santoku needs about 20cm of clear board length; an 18cm santoku needs closer to 30cm. Also check your knife block or drawer: a longer blade may not fit a shallow slot. A frequent mistake is buying an 18cm knife for a tiny kitchen island where it will clatter against nearby items. Measure your board and storage slot before buying; if either is under 25cm, the smaller size is the safer fit.
4. Decide between one do-it-all knife and a pair: If you want a single santoku, choose 18cm for general cooking or 13cm if you mostly prep vegetables and small portions. If you already own a large chef’s knife, add a 12cm or 13cm santoku for quick tasks instead of duplicating size. Checkpoint: two knives of similar length add less value than one large and one small. Buy the size that fills a gap in your current knives, not the size that matches what you already own.

Two Grunwerg santokus to consider

• Santoku Knife 12cm 2400 Series: The 2400 Series Santoku Knife is 12cm long and has a full tang construction with a POM and stainless steel handle. The compact blade suits smaller hands and quick prep, while the full tang adds solidity for controlled slicing.

  

• 13cm Santoku Knife: The 13cm Santoku Knife is described as a small Japanese-style chef’s knife for slicing, dicing and mincing vegetables, fruit and meat. That makes it a practical choice if you want one short blade for everyday vegetable prep rather than a full-size chef’s knife.