Written and maintained by CASRAI Editorial Board
Last updated
This page is general product information, not medical advice or instruction in any procedure. It is for anyone who needs to match a numbered scalpel blade to the handle family it belongs to, for example when reading a supplier catalogue or an instrument list. Surgical blades are identified by number, and the number tells you the blade shape and, within a manufacturer’s range, which handle it fits. It does not tell you a length in millimetres.
Always check your product’s labelling and the manufacturer’s instructions for use before relying on any chart, including this one: the maker’s labelling and instructions for use are the authority for the exact product in your hands.
Scalpel blade sizes chart: numbers, shapes and handle fit
The table follows the manufacturer’s own grouping (Swann-Morton’s No. 3 and No. 4 fitment ranges). Shape descriptions are given only where the maker or supplier documents describe them; “Not specified” means the number is listed in the range but no shape description is published there.
| Blade number | Shape / typical description | Handle fitment |
|---|---|---|
| 10 | Broad, curved edge (WPI) | No. 3 range (Swann-Morton); handles #3 and #7 (WPI) |
| 11 | Sharp, pointed tip (WPI) | No. 3 range; handles #3 and #7 |
| 12 | Crescent-shaped hook (WPI) | No. 3 range; handle #7 |
| 15 | Small, curved edge (WPI) | No. 3 range; handles #3 and #7 |
| 06, 09, 13, 14, 16 | Not specified | No. 3 range |
| 10A, 10R, 11P, 12D, 15A, 15C, 15T | Variants of the base shapes, listed in the same range (shape detail not specified) | No. 3 range |
| E/11, Sabre D/15, Sabre E/11 | Not specified | No. 3 range |
| 40 | Double-edged blade (Swann-Morton) | No. 3 range |
| SG3 | Minor skin graft blade, as named by Swann-Morton | No. 3 range |
| 18, 19, 20, 21, 22, 22A, 23, 24, 25, 25A, 26, 27, 36 | Larger blade shapes, grouped by Swann-Morton in its No. 4 range | No. 4 range (handles 4, 4L, 6B); WPI pairs handle #4 with #20 to #25 |
How to read the numbers
The number identifies a blade shape, and the fitment group tells you which handles accept it. Swann-Morton describes blade shapes 6 to 16, plus the double-edged 40 and the SG3, as compatible with its No. 3 fitment handles, and shapes 18 to 36 as compatible with its No. 4 fitment handles. A letter after a number (10A, 15C, 11P) marks a variant listed alongside the base shape; read the maker’s catalogue entry for what differs.
In practice the numbers split into two bands: low numbers (about 6 to 16) are the smaller blades in the No. 3 family, and numbers from 18 upward are the larger blades in the No. 4 family. For a close look at the two most-compared shapes, see #10 blade vs #15 blade.
Matching a blade to a handle
Handles are numbered on the same fitment logic. According to the Swann-Morton range pages:
| Fitment | Handles listed | Blades listed |
|---|---|---|
| No. 3 | 3, 3L, 5B, 7, 9, B3 | 06 to 16 and variants, 40, SG3 |
| No. 4 | 4, 4L, 6B | 18 to 27, 36 |
One supplier guide (WPI) lists a similar pairing: handle #3 for #10, #11 and #15 blades; handle #7 for #10 to #15 blades; and handle #4 for #20 to #25 blades. A No. 18 blade is described by Swann-Morton as fitting handles 4, 4L, 4 Graduated and 6B. Retractable designs are covered separately in retractable scalpel, which cites the PenBlade instructions for use listing blade sizes 10, 11P and 15.
Equivalence notes: why there is no gauge or mm column
Needle gauge and French sizes measure diameter, and they do not apply to scalpel blades. The maker documents cited here give blade numbers and handle fitment but no millimetre dimensions, so this chart does not translate numbers into lengths. If you need a dimension, take it from the maker’s product page or instructions for use for that exact product. S, M and L sizing does not apply to blades either; the number is the size designation.
Regulatory status of blades and handles
In the United States, 21 CFR 878.4800 covers manual surgical instruments for general use: nonpowered, hand-held or hand-manipulated devices, reusable or disposable, with the scalpel blade, scalpel handle and one-piece scalpel named in the regulation. The FDA classifies them as Class I (general controls) and exempts them from premarket notification, subject to the limitations in 21 CFR 878.9. That tells you how the category is regulated; it does not itself define blade numbers or shapes.
Common mix-ups
- Skipping the product documentation. Check the maker’s own labelling or instructions for use for the exact blade and handle before treating a pairing as confirmed.
- Mixing fitment families. A No. 3 fitment blade and a No. 4 fitment blade are listed with different handles in the Swann-Morton ranges.
- Treating letters as sizes. Suffixes such as A, C, P, R and T denote variants, not a bigger or smaller version.
- Confusing a blade with the instrument. A scalpel is a blade plus handle (or a one-piece device); see what a scalpel is. A bistoury is a separate instrument name, and plastic surgery instruments lists others.
FAQ
Do #10 and #15 blades fit the same handle?
Yes, according to the maker and supplier documents cited here: Swann-Morton lists both in its No. 3 fitment range, and WPI pairs handles #3 and #7 with both. Check the specific handle’s labelling.
Is there a size in millimetres for each blade number?
This chart does not give one, because the manufacturer pages cited list numbers and handle fitment only. Take dimensions from the product’s own instructions for use.
What do the handle numbers mean?
They name the fitment family. In the Swann-Morton ranges, handles 3, 3L, 5B, 7, 9 and B3 belong to the No. 3 family, and 4, 4L and 6B to the No. 4 family.
Are blades sterile?
Swann-Morton’s No. 18 product page describes sterile blades in individual foil packs of 100. Sterility depends on the product, so read the packaging.
Sources
- Swann-Morton, No. 3 range (manufacturer): https://www.swann-morton.com/product_range/19.php, checked 2026-10-30.
- Swann-Morton, No. 4 range (manufacturer): https://www.swann-morton.com/product_range/2.php, checked 2026-10-30.
- Swann-Morton, No. 18 product page (manufacturer): https://www.swann-morton.com/product/34.php, checked 2026-10-30.
- WPI, Disposable Scalpel Blade Guide (supplier guide): https://www.wpiinc.com/blogs/all/disposable-scalpel-blade-guide, checked 2026-10-30.
- eCFR, 21 CFR 878.4800 (regulator): https://www.ecfr.gov/current/title-21/chapter-I/subchapter-H/part-878/subpart-E/section-878.4800, checked 2026-10-30.
