NEF to BMP Converter

NEF vs BMP — Which Should You Convert To?

You are here because something on a Windows machine wants a .bmp and will not take your Nikon RAW. The short answer: BMP will get the picture into that program, but it is not the "uncompressed, perfect copy" its reputation suggests. Every BMP path on this page reduces colour — one of them to 32,768 possible colours, the other two to a palette of 256 or fewer — and none of them writes a 24-bit true-colour bitmap. If what you actually wanted was a lossless full-colour still, NEF to PNG is the correct target and this page is not.

Side-by-side Comparison

The Three Quality Presets, Compared

The Quality preset dropdown is the only meaningful control on this page, and on a BMP target it shows just three entries. They are not three grades of the same encoder — they are three different pipelines with genuinely different outputs:

Two things in that table deserve calling out. First, there is no 24-bit true-colour option — High is 16-bit, not 24-bit, so a smooth sky loses gradient steps even on the best setting. Second, RLE8 is not automatically a win: on a flat graphic it took our 24 MB test frame down to 1.2 MB, but on a dithered photograph it produced a larger file than storing the pixels uncompressed would have, because Floyd–Steinberg dither breaks up the runs that RLE depends on.

When to Pick Each Preset

• High — anything photographic. It is the only preset that keeps a continuous-tone image looking continuous, and the fixed 2-bytes-per-pixel size is at least predictable.
• Medium — flat artwork, screenshots, logos, diagrams. RLE8 shines on large areas of one colour, and 256 colours is plenty for that kind of image.
• Low — only when a downstream tool demands a very small palette. At 86 colours a photograph posterizes visibly.
• Set it explicitly. Do not rely on the dropdown's starting position. The configuration's declared default for image quality is a preset that is not offered on BMP, so what you see selected is simply the first entry that survived filtering. Click the preset you want before converting.

How to Convert NEF to BMP

1. Upload Your NEF File: Drag your .nef onto the page or click "+ Add Files". You can queue several Nikon RAW files and convert them with the same settings.
2. Pick a Quality preset: Open Advanced Options and choose High, Medium or Low under Image Compression — these are three different bitmap formats, not three quality grades, so choose deliberately.
3. Set Image resolution (Optional): Keep original, scale by Resolution Percentage, choose a Preset Resolution, or type an exact Width × Height. This is the only lever that meaningfully shrinks a High-preset bitmap.
4. Convert and Download: Click Convert and save the .bmp. Files upload over an encrypted connection, are processed on our servers, and are deleted automatically after a few hours — no sign-up, no watermark.

Frequently Asked Questions

Is the BMP output 24-bit true colour?

No — and this is the single most common wrong assumption about this conversion. The High preset writes a 16-bit RGB555 bitmap: 5 bits each for red, green and blue, which is 32 levels per channel and 32,768 possible colours in total. Medium and Low are palette formats capped at 256 and 86 colours respectively. There is no true-colour BMP path here at all. If you need 8 bits per channel, NEF to PNG is lossless and full-colour, and NEF to TIFF goes to 16 bits per channel.

How much colour does the High preset actually throw away?

More than the file size suggests. We rendered a test frame containing 837,461 distinct colours through the High preset and the output held 5,976 — RGB555 quantises each channel to 32 levels, so anything with a smooth gradient will show banding under close inspection. The pixels are stored exactly as written, with no further compression loss on top; the loss happens at the moment of quantisation.

Why is my Medium-preset BMP bigger than an uncompressed one would be?

Because RLE8 encodes runs of identical pixels, and dithering destroys runs. Medium applies Floyd–Steinberg dither before quantising to 256 colours, which scatters neighbouring pixels across the palette on purpose to hide banding. On our photographic test frame that produced 29,556,802 bytes, where storing the same 256-colour image with no compression would have taken about 24,001,162. Run the same preset on a flat graphic and RLE8 works exactly as advertised — the same frame came out at 1,235,798 bytes.

How large will a full-resolution BMP be?

On the High preset the arithmetic is exact: two bytes per pixel plus a 54-byte header. A 24-megapixel Nikon frame at 6000 × 4000 measured 48,000,054 bytes, and a 45-megapixel frame at 8256 × 5504 works out at roughly 91 MB. Medium and Low depend entirely on the picture's content. If the size is a problem, lower Image resolution — it is the only control on this page that changes the pixel count.

Which preset is selected when the page loads, and does it matter?

It matters enough to be worth one click. The shared image-quality configuration declares a default preset that is not among the options offered on BMP, so the dropdown falls back to showing the first entry that is available rather than a deliberately chosen default. Pick High, Medium or Low yourself before converting so you know which of the three bitmap formats you are getting.

Will I lose my RAW editing latitude?

Yes, and permanently for that file. Nikon keeps white balance, hue, tone and sharpening as instruction sets inside the NEF rather than applying them to the sensor data, which is what lets you change your mind about them indefinitely. Producing a BMP forces the pipeline to demosaic that data and commit to one interpretation. Keep the .nef as your master and treat the bitmap as a delivery copy.

Can I control DPI, bit depth, or the background colour?

Not on this target. The DPI selector, bit-depth selector, compression-type selector and background-colour picker exist in our image pipeline but none of them renders on a BMP output — the format's bit depth is decided by which preset you choose, and there is no transparency to composite. What does render is the full Image resolution group: percentage, keep original, height presets, width only, height only, or an exact width × height.

Why won't the BMP open in my browser or phone gallery?

Browser and mobile support for BMP is patchy, especially for the RLE8-compressed variants that the Medium and Low presets produce. BMP was designed as a Windows display format, not a delivery format. For anything that has to be viewed rather than ingested by a specific program, convert to NEF to JPG for size or NEF to PNG for a lossless full-colour copy.

Should I convert to BMP at all?

Only if a specific Windows application, imaging pipeline or embedded device requires .bmp and refuses everything else. That is a real requirement and this page serves it honestly — but if you have any choice, PNG gives you lossless 8-bit-per-channel colour in a much smaller file, and JPG gives you a small shareable photo. The NEF converter hub lists every target we support from Nikon RAW, and if you already have bitmaps to shrink, BMP compression works on them directly.