Xem Studiomeasured geometryLibrary › Vintage forms › Retro media · 1990 ·
3.5 in floppy disk (90 mm diskette)
What are the exact dimensions of a 3.5 inch floppy disk? · Modern device · basis: ECMA-147 (ISO/IEC 9529-1), 90 mm flexible disk cartridge, 1.44 MB high density (ISO Type 303)
Also called: 3.5 floppy disk dimensions, 3.5 inch floppy size mm, floppy disk size, 1.44mb floppy dimensions, diskette dimensions, disquete 3.5 medidas, disquete 3,5 dimensões, Diskette 3,5 Zoll Maße
Exact dimensions. True size, with no printing tolerance added.
- length
- 94.0 mm
- width
- 90.0 mm
- height
- 3.3 mm
Notes
- A 3.5 in floppy disk case is 94.0 × 90.0 × 3.3 mm (ECMA-147 §6.1: L1 = 94.0 ±0.3 mm, L2 = 90.0 +0.4/−0.1 mm, thickness E1 = 3.3 ±0.2 mm in the 8.5 mm bands along the two edges). Three corners are R2.0 ±1.0 mm, the fourth is cut at 45° ±2°, and the case edges are rounded R0.40 ±0.25 mm.
- The hub access hole on side 0 is Ø26.50 mm min., centred 40.00 × 31.00 mm (±0.15) from the reference axes, which pass through the primary locating hole (Ø3.6 ±0.1 mm). The secondary locating hole is 80.0 ±0.2 mm along the X axis, 3.6 × 4.4 mm. Head windows are 9.00 ±0.20 mm wide.
- The file is the case at the published size: a 94.0 × 90.0 × 3.3 mm plate with R2.0 corners, no printing allowance. The 45° corner, shutter, holes and label recess are placed by the standard's figures, not its text, so they are not modelled; build around the envelope and check a real disk.
- ECMA-147 covers the 1.44 MB high-density disk; the 720 KB double-density disk is ECMA-125 (ISO/IEC 8860). Makers' shells may differ in shutter and label detail inside these limits — a measured Xem scan of the shutter and write-protect slide is planned.
3.5 in floppy disk size chart
| dimension | value |
|---|---|
| case length (L1) | 94.0 mm ±0.3 |
| case width (L2) | 90.0 mm +0.4 / −0.1 |
| thickness (E1) | 3.3 mm ±0.2 |
| corner radius, three corners (R1) | 2.0 mm ±1.0 |
| fourth corner | 45° ±2° |
| case edge radius (R2) | 0.40 mm ±0.25 |
| hub access hole (D1) | Ø26.50 mm min. |
| hub hole centre from reference axes | 40.00 × 31.00 mm ±0.15 |
| primary locating hole (D2) | Ø3.6 mm ±0.1 |
| secondary locating hole | 3.6 × 4.4 mm, 80.0 mm ±0.2 along X |
| head window width (L18) | 9.00 mm ±0.20 |
| label area | L11 3.5 mm min., L12 76.5 mm max. |
Where the files are
Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.
| Ecma International | ECMA-147: 90 mm flexible disk cartridges, ISO Type 303 (PDF) | web | Publisher's page; dimensions are facts |
Free files
★ Free files 1 parts. Generated by Xem Studio from the standard; threads are plain cylinders at major diameter. CC BY 4.0. index.json
| 3-5-inch-floppy-disk-90-mm-case | Case 94.0 × 90.0 × 3.3 mm, R2.0 corners (ECMA-147 nominal; shutter and holes not modelled) | STEP · STL |
https://xemstudio.com/mcp to Claude, ChatGPT, Cursor or any MCP client (free, no account, one minute) and it can look up exact sizes, mating fits and free STEP/STL from every chat.Plain text: sheet.txt · JSON: /api/geometry?object=3-5-inch-floppy-disk-90-mm
Fits with
Questions
How big is a 3.5 inch floppy disk?
94.0 × 90.0 × 3.3 mm (ECMA-147): three R2.0 corners and one 45° corner.
Is a 3.5 inch floppy really 3.5 inches?
No: the disk inside is 90 mm; the case is 94.0 × 90.0 mm (3.70 × 3.54 in).