Files carrying a .nef suffix usually are what they say they are, but the suffix is not proof. Nikon’s lossy-compressed raw is not bit-recoverable; the camera’s compression is applied at capture.
| Usual MIME type | image/x-nikon-nef |
| Extension | .nef |
| Full name | Nikon Electronic Format |
| Signature | 49 49 2A 00 at offset 0 |
What the file holds
TIFF/EP-based: a standard IFD chain plus Nikon maker notes; lossy compression is optional and can be set in-camera.
The first bytes
Identify it before you open it — 49 49 2A 00 at offset 0. That single look answers most of the questions we get about .nef.
Opening it without the program that made it
Installed options: Nikon NX Studio, Adobe Camera Raw / Lightroom, Capture One, ViewNX 2, Darktable, RawTherapee. None of them have to be the program that made the file: Universal Viewer reads it and writes nothing back.
When you have to convert
The targets people actually ask for are .jpg, .png, .dng, .tif. Each one has its own page with the settings that matter: nef → jpg, nef → png, nef → dng, nef → tif
Notes from the file library
Files of this kind are catalogued with the family named in the table above. The family groups them by what a file carries, not by the application that wrote it, which is why two extensions from the same application can sit in different families.
Two things decide whether a file can be opened on a machine that never had the application that made it: the header, which says what the container is, and the structure behind it, which says whether the contents can be read at all. The conversion guides listed on the page cover the targets that come up most often.
Format pages are rebuilt with each release of the toolset, and the review line at the bottom of the page is when an editor last checked the entry against a file. If a page disagrees with a file you have, send the first sixteen bytes and the build number to the support address and the entry is corrected in the next build.
Reviewed 2026-10-05 by M. Halvorsen.