RAW Image Format Explained: Files, Sizes, and How to Handle Them

If you've ever pulled photos off a new camera and wondered why the files are five or ten times bigger than the JPEGs from your phone, you've already met the raw image format. RAW is the unprocessed sensor data your camera captures the moment you press the shutter. No baked-in contrast, no sharpening, no compression artifacts. Just the data, ready for you to develop later, like a digital negative.

That sounds great until you realize a single afternoon shoot can fill 30GB of storage. So in this guide we'll break down what the raw image format actually is, why files are so massive, the common formats by camera brand, when to use RAW vs JPEG, and how to convert and compress them for delivery. Written for hobbyists and content creators, not pixel-peeping pros.

What Is the RAW Image Format?

The raw image format is a class of files that store the unprocessed data captured directly by your camera's image sensor. Where a JPEG is a finished image, a RAW file is more like the recipe and ingredients combined. The camera writes down everything the sensor saw and leaves the cooking to you in software like Lightroom or Capture One.

People call RAW a "digital negative" because the analogy holds up. A film negative isn't the photo you hang on the wall, it's the source you print from. Same idea: RAW is the master, not the deliverable.

A typical RAW file contains:

• Full sensor readout at 12, 14, or 16 bits per channel (vs 8 bits for JPEG)
• Linear, gamma-uncorrected data that hasn't been white-balanced
• Embedded metadata like ISO, shutter speed, aperture, lens info, and GPS
• A small JPEG preview for camera and Finder thumbnails

There's no single "RAW" format the way there's a single JPEG. Each camera maker rolls their own, which is why your computer might happily open one file and stare blankly at another.

How RAW Differs From JPEG and HEIC

The cleanest way to think about it: JPEG and HEIC are delivery formats. RAW is a working format.

When your camera saves a JPEG, it does a lot of behind-the-scenes processing in a fraction of a second: white balance, contrast curve, sharpening, noise reduction, color profile, then lossy compression. The result looks great straight out of the camera but is essentially a finished print. Not much room to push around in editing.

HEIC (the format iPhones use by default) does the same job with a more modern codec, so you get JPEG-like quality at roughly half the size. Still a finished image, just packaged more efficiently. If you've got a folder of .heic files to share around, our guide on how to batch convert HEIC to JPG walks through the easiest way.

A RAW file skips almost all of that. The processing decisions are deferred to you. More work and bigger files in exchange for vastly more flexibility.

Property	RAW	JPEG	HEIC
Bit depth per channel	12-16 bit	8 bit	8 or 10 bit
Compression	Lossless or none	Lossy	Lossy (HEVC)
White balance baked in	No	Yes	Yes
Editing latitude	Very high	Low	Low-Medium
File size (24MP shot)	25-50 MB	5-10 MB	2-5 MB
Universal viewing	No	Yes	Mostly

For a broader look at when each format is the right call, see our writeup on the best image format for websites.

Why RAW Files Are So Big

A few things stack up to make raw image format files much larger than their JPEG equivalents.

More bits per channel. A JPEG stores 8 bits per color, giving you 256 levels of each. A RAW file stores 12, 14, or 16 bits per channel, for 4,096 to 65,536 levels. That's where all the recovery latitude comes from, but it makes every pixel two to four times heavier.

Little or no lossy compression. JPEG throws away data the human eye is unlikely to notice. RAW formats either skip compression entirely or use lossless compression. Our explainer on 8 lossless compression file types explained is a good companion read.

Full sensor data plus previews. RAWs include the entire sensor readout, an embedded full-resolution JPEG preview, and extensive EXIF and lens correction metadata.

Add it all up and a 24MP camera might output an 8MB JPEG and a 32MB RAW from the same shot. A 45MP body? You're looking at 80-100MB per RAW.

Common RAW Formats by Manufacturer

Every camera company invented their own raw image format, mostly so they could control how the files get processed. Here's the lineup you're likely to encounter.

Canon: .CR2 and .CR3

Canon's older DSLRs (5D Mark III era and earlier) write .CR2. Newer mirrorless bodies like the R5, R6, and R8 use .CR3, which adds compressed RAW (C-RAW) for smaller files.

Nikon: .NEF

"Nikon Electronic Format." Offers uncompressed, lossless compressed, and lossy compressed variants under the same .NEF extension. Most photographers stick with lossless compressed for a free 30-40% size reduction.

Sony: .ARW

"Alpha RAW," used by every A7, A1, and FX series body. Sony also offers compressed and uncompressed options plus a newer "lossless compressed" mode.

Fujifilm: .RAF

Used across their X-series and GFX cameras. RAFs from Fuji's X-Trans sensors have a non-Bayer color filter array, which is why some editors handle them better than others.

Olympus / OM System: .ORF

Used by Olympus and OM System Micro Four Thirds cameras. Smaller sensors mean smaller files, typically 15-25MB.

Adobe: .DNG (Digital Negative)

DNG is Adobe's open, universal raw image format. Some cameras (Leica, Pentax, drones, iPhones in ProRAW mode) write DNG natively. You can also convert any other RAW to DNG using Adobe's free DNG Converter. Every modern editor can open a DNG, which makes it great for archiving. For converting DNGs out for delivery, see our convert DNG to JPG walkthrough.

Apple: .HEIC (with ProRAW)

HEIC is normally a finished, processed image, but iPhone Pro models can shoot Apple ProRAW, which wraps DNG-style raw data inside an HEIC container. You get most of a real RAW's editing latitude at around 25MB instead of 5MB.

Pros of Shooting RAW

Why put up with the extra storage and workflow step?

• Recovery latitude. Blew out the sky or crushed the shadows? RAW lets you pull back two or three stops in either direction. JPEG already threw that data away.
• Better white balance fixes. Change WB in post like you'd never set it at all. JPEG will fight color casts forever.
• Smoother gradients. Extra bit depth means you can push contrast hard without banding in the sky.
• Better noise reduction. AI denoisers like Lightroom's Denoise or Topaz Photo AI work dramatically better on RAW data.
• Future-proofing. RAW processing software keeps improving, so the same file looks better in next year's editor. JPEGs are frozen.

Cons of Shooting RAW

It's not all upside.

• Huge files. Storage cost, slower buffer when shooting bursts, more upload and backup time.
• Slower workflow. Every shot needs at least a quick edit and an export before you can share it.
• Software required. RAW always needs processing software. You can't just double-click a .CR3 on grandma's PC.
• Manufacturer lock-in. New cameras sometimes ship before Lightroom adds support for their raw image format.

When to Use RAW vs JPEG

A simple rule of thumb:

Shoot RAW when

• You plan to edit the photos
• The lighting is tricky (high contrast, mixed light, low light)
• It's a once-in-a-lifetime shot you'll never reshoot
• You're being paid for the work
• You're learning and want to experiment

Shoot JPEG when

• You need the photos straight out of camera
• You're shooting high-volume sports or events with tight turnaround
• Storage or buffer speed is a hard constraint
• The output is for casual sharing only

A lot of cameras let you shoot RAW + JPEG simultaneously, which is the best of both worlds if you have the storage. You get an instant-share JPEG and a master RAW for later.

Editing RAW Files

Every RAW workflow starts with a "develop" step where you tell the software how to interpret that linear sensor data. The main options:

• Adobe Lightroom Classic / CC – Industry standard, great cataloging, subscription-based.
• Capture One – Preferred by many studio shooters for its color science. Has a perpetual license option.
• Apple Photos – Built into macOS, handles ProRAW and most camera RAWs. Surprisingly capable for casual edits.
• darktable – Free, open-source, runs everywhere. Steeper learning curve.
• Affinity Photo – One-time purchase, no subscription, includes a RAW develop persona.
• DxO PhotoLab – Excellent noise reduction (DeepPRIME) and lens corrections.

For most hobbyists, Apple Photos carries you a long way. When you want layers, masks, and detailed color work, Lightroom or Capture One is the next step.

Converting RAW to JPEG or HEIC for Delivery

You almost never deliver the RAW itself. Whether you're sending photos to a client or posting to Instagram, you'll export a JPEG (most common) or HEIC (smaller, less universal).

The export workflow in any RAW editor:

1. Finish your edits.
2. Choose JPEG or HEIC as the export format.
3. Pick a quality setting (80-90% gives near-invisible artifacts).
4. Optionally resize for the destination (e.g., 2048px long edge for web).
5. Export.

Lightroom's Export dialog, Capture One's Process Recipes, and Apple Photos' File > Export all do the same job in batches. For squeezing those exported JPEGs even smaller, our how to compress JPEG guide has the details.

Compressing RAW Files for Archive

Once a shoot is done you usually want to archive the RAWs for future re-edits, but they take up enormous space. A few options:

Convert to lossless compressed DNG. Adobe's free DNG Converter shaves 20-30% off file size with zero quality loss. Downside: you lose some manufacturer-specific metadata.

Use in-camera lossless compression. Many newer cameras offer a "lossless compressed" RAW mode identical in quality to uncompressed but 30-40% smaller. Turn it on if your camera supports it.

ZIP or 7z the folder. Already-compressed RAWs won't shrink much (5-15%), but uncompressed RAWs from older bodies can drop 30-50% in a 7z archive. Fine for cold storage.

For the exported JPEGs that come out of your RAW workflow, a dedicated image compressor pays off. Compresto batch-processes high-resolution JPEGs and shrinks them 50-70% with no visible quality loss, which matters when you're delivering galleries to clients or uploading to a portfolio. Our image compressor software roundup compares the main contenders.

For general size-reduction techniques see how to make image file size smaller, and for PNG-specific resizing, how to resize PNG.

File Size Comparison: RAW vs JPEG vs HEIC

Here's roughly what you can expect from the same 24MP shot saved in different formats:

Format	Typical File Size	Bit Depth	Editable?
Uncompressed RAW (.CR3, .NEF, .ARW)	45-55 MB	14-bit	Yes, fully
Lossless compressed RAW	28-38 MB	14-bit	Yes, fully
Lossy compressed RAW (C-RAW)	18-25 MB	14-bit	Mostly
DNG (lossless)	25-35 MB	14-bit	Yes, fully
Apple ProRAW (HEIC + DNG data)	20-30 MB	12-bit	Yes
JPEG (high quality)	6-10 MB	8-bit	Limited
HEIC (high quality)	2-4 MB	8-10 bit	Limited
JPEG (web-optimized, 2048px)	400-800 KB	8-bit	No

For a 45MP body, multiply most of those numbers by about 1.8x.

Frequently Asked Questions

What's the difference between RAW and JPEG?

JPEG is a finished image with all the camera's processing baked in. RAW is the unprocessed sensor data with those decisions deferred to editing. RAWs are 4-10x larger but give you vastly more flexibility to fix exposure, color, and noise after the fact.

Are RAW files worth it?

If you edit your photos at all, yes. The recovery latitude alone justifies the bigger files. If you only ever shoot for casual sharing and never open an editor, JPEG is fine and lighter on storage.

How do you compress a RAW file?

Use lossless compressed RAW in your camera settings, or convert to lossless DNG with Adobe's free DNG Converter. For archive, ZIP or 7z folders of RAWs work for modest savings. For delivery, don't compress the RAW itself: export to JPEG or HEIC and compress that with a tool like Compresto.

Can you open RAW files on Mac?

Yes. macOS has built-in support for most major raw image format types. Preview, Apple Photos, and Finder thumbnails all work natively for Canon, Nikon, Sony, Fujifilm, Olympus, and others. For brand-new camera models you might need a macOS update.

Is DNG better than RAW?

DNG is a RAW format, just an open one. Advantage: universal compatibility and built-in lossless compression. Disadvantage: converting from a manufacturer's native RAW to DNG can drop some camera-specific metadata. For archival, DNG is hard to beat.

How big are RAW files?

Roughly 1MB per megapixel for lossless compressed RAW, 1.5-2MB per megapixel for uncompressed. A 24MP camera produces 24-50MB files; a 45MP camera, 45-90MB; a 100MP medium format body, up to 200MB.

Wrapping Up

The raw image format isn't magic, it's just deferred decisions. You trade bigger files and a slower workflow for the freedom to develop photos the way you want, days or years after you shot them. For anything you care about, that trade is almost always worth it.

One thing to remember: RAWs are working files, not delivery files. Always export to JPEG or HEIC before sending to clients or posting online, and compress those exports so your portfolios load fast.

If you're sitting on a folder of exported JPEGs from your RAW workflow and want to shrink them for the web without trashing the quality, download Compresto at https://compresto.app. Drag in a folder, pick a quality target, and get back files that are 50-70% smaller.