Photo File Size Calculator
Convert megapixels to megabytes. Pick your camera resolution and file format to see what one photo actually weighs in HEIC, JPEG, WEBP, PNG, RAW, ProRAW or TIFF, and what a full camera roll of them adds up to in GB.
Photo File Size Calculator
Resolution
12.2 MP is the standard iPhone capture (4032 x 3024 pixels).
Format and quality
HEIC is the iPhone default and runs about half the size of JPEG at the same quality.
Phone cameras save at high quality by default.
Your library
Open Settings, then Photos, to see your exact count.
The uncompressed figure is the number most "megapixels to MB" converters return. It is the sensor data before the encoder touches it, not the file your phone writes to disk.
Knowing the number is the easy half
Swipe44 puts the real on-disk size on every card while you swipe, right to keep and left to delete. Duplicates get grouped on the phone itself. Everything you marked goes in one batch behind a single confirmation, and you find out exactly how many megabytes came back.
The same photo in every format
| Format | Per photo | Total for 1,000 photos | vs. selected |
|---|
At your megapixel and quality settings. Lossless formats ignore the quality setting.
How photo file size is actually calculated
Every raster image starts from the same arithmetic: width times height times bits per pixel, divided by 8. A 12.2 MP iPhone frame is 4032 by 3024 pixels, which is 12.2 million pixels. At 8-bit RGB (24 bits, or 3 bytes, per pixel) that is 36.6 MB of data.
That number is the uncompressed size, and it is where most megapixels-to-MB converters stop. It is also off by more than an order of magnitude as an answer to the question people are actually asking. Your phone never writes 36.6 MB to disk. It runs the frame through an HEIC encoder and puts down about 2.5 MB, a compression ratio of roughly 14:1. Save it as JPEG instead and you get about 5 MB, or roughly 7:1.
So this calculator leads with the compressed size, the one that matches what you see in the Files app, and keeps the uncompressed figure underneath, labelled for what it is: raw sensor data. If a converter tells you a 12 MP photo is 36 MB, it is describing a file format nobody uses.
JPEG vs HEIC vs PNG vs RAW: how big is each format?
Format moves the number far more than resolution does. A 12 MP ProRAW file is bigger than a 48 MP HEIC. Below is the same 12 MP frame written seven ways, with the per-megapixel rule of thumb behind each one.
| Format | MB per megapixel | 12 MP | 48 MP |
|---|---|---|---|
| HEIC / HEIF (iPhone default) | 0.21 | 2.5 MB | 10 MB |
| WEBP (lossy, q80 to q85) | 0.31 | 3.8 MB | 15 MB |
| JPEG (high quality, q90 to q95) | 0.42 | 5 MB | 20 MB |
| PNG (lossless, photographic content) | 1.0 | 12 MB | 48 MB |
| RAW / DNG (14-bit, lossless-compressed) | 1.1 | 13 MB | 53 MB |
| Apple ProRAW (12-bit linear DNG) | 2.1 | 25 MB | 100 MB |
| TIFF (uncompressed 8-bit RGB) | 3.0 | 36 MB | 144 MB |
Two anchors are worth remembering: HEIC is about half of JPEG, and WEBP sits about 25% under JPEG. HEIC manages it with HEVC intra-frame coding, a generation ahead of JPEG's 1992 compression, which is why every iPhone since iOS 11 ships with High Efficiency on by default. TIFF at the bottom of the table is barely a compression format at all. At 3 bytes per pixel it is exactly the uncompressed sensor data, which is why its number matches the raw figure in the calculator.
Every row is a typical case, not a promise. Compression works on detail, so a 12 MP HEIC of a flat sky might come in at 900 KB while the same shot of a forest canopy runs 4 MB. Expect about 20% of give either way.
What this means for your camera roll
Multiply out and the picture changes. 5,000 photos at 12 MP HEIC is about 12.5 GB, which is nothing on a modern phone. The same 5,000 shot at 48 MP is about 50 GB, and if you left the camera on Most Compatible so they came out as JPEG, double it again.
For most people, though, resolution is not the problem. Volume is. The gigabytes are sitting in duplicates, in the burst sequence where you kept all eleven frames, in screenshots of things you dealt with months ago, in the four near identical photos of the same coffee. None of that is a megapixel question. It is a housekeeping question, and no camera setting will fix it for you.
That is what Swipe44 is for. You work through the camera roll by swiping, right to keep and left to delete, from Recents, from Random, or one month at a time. Every card carries the real on-disk size, so you can see what each decision is worth. Duplicates get grouped by on-device perceptual hashing, ready to review together. Everything you mark collects in a pending pile, then goes in one batch behind a single system confirmation, with a tally of the space you got back. Nothing is uploaded and no account is needed. iCloud originals are never downloaded.
Once you know how many gigabytes your library really is, the iCloud Storage Cost Calculator turns that figure into a monthly bill and tells you what a cleanup would save.
Megapixels, bit depth and compression explained
Megapixel. One million pixels. A 4032 by 3024 sensor produces 12,192,768 pixels, which is marketed as 12 MP. Megapixels describe the grid, not the file.
Bit depth. How many bits describe one pixel's colour. 8-bit grayscale is 8 bits per pixel, standard 8-bit RGB is 24 (3 bytes), 16-bit RGB is 48. This calculator assumes 24 for the uncompressed baseline, the normal consumer-photo case.
Compression ratio. Uncompressed size divided by the size on disk, written N:1. A 12 MP HEIC at 2.5 MB against 36 MB of sensor data comes out around 14:1. Higher means smaller.
Lossy vs lossless. Lossy formats (HEIC, JPEG, WEBP) discard detail your eye is unlikely to miss, and they give you a quality dial. Lossless formats (PNG, TIFF, RAW, ProRAW) keep every bit, so there is no dial to turn and the files are much bigger.
Decimal vs binary units. This page counts 1 MB as 1,000,000 bytes and 1 GB as 1,000,000,000 bytes, the way Apple and Google report storage. Your phone's own storage screen counts in binary, which is why a "128 GB" iPhone reads as about 119 GB.
Frequently Asked Questions
Common questions about photo file size calculator
How do I convert megapixels to MB?
There is no fixed conversion. Megapixels count pixels; megabytes measure what is left after the encoder has been at it. The raw arithmetic is pixels times bits per pixel, divided by 8, so a 12 MP photo at 8-bit RGB (24 bits per pixel) works out at 36 MB of sensor data. No camera writes that to disk. Once the phone encodes it, a 12 MP shot lands at roughly 2.5 MB in HEIC or 5 MB in JPEG. If you want a shortcut, use megabytes per megapixel: about 0.21 for HEIC, 0.42 for JPEG, 0.31 for WEBP, 1.0 for PNG, 1.1 for RAW and 2.1 for ProRAW.
How many MB is a 12MP photo?
About 2.5 MB as HEIC, the iPhone default. The same shot runs about 5 MB as a high quality JPEG, about 3.8 MB as WEBP, about 12 MB as PNG, about 13 MB as camera RAW and about 25 MB as Apple ProRAW. Behind all of those sits about 36 MB of uncompressed sensor data (37 MB at the iPhone sensor's true 12.2 MP), and that is the number calculators hand you when they ignore compression entirely.
How many MB is a 48MP iPhone photo?
A 48 MP HEIC Max file is about 10 MB, roughly four times a standard 12 MP HEIC. As JPEG it runs about 20 MB. Shoot the same frame in 48 MP ProRAW and you are looking at about 100 MB per photo, which is why a single afternoon of ProRAW can cost several gigabytes.
Why is my photo smaller than the calculator says?
Compression works on detail, and detail varies with the picture. A flat blue sky or a plain wall squashes down much harder than foliage or a crowd, so two 12 MP HEICs off the same phone can differ by a factor of three. What you get here is the typical case for an ordinary photo, not a promise about any single file. Read it as an estimate with roughly 20% of give either way.
Is HEIC really half the size of JPEG?
Roughly, yes. HEIC uses HEVC intra-frame coding, a generation ahead of JPEG's 1992 vintage compression, and it holds about the same picture quality in about half the bytes. In this calculator a 12 MP HEIC is 2.5 MB against 5 MB for JPEG. Which is why every iPhone since iOS 11 ships with High Efficiency turned on by default.
How much storage do 1,000 photos take?
About 2.5 GB if they are 12 MP HEIC, about 5 GB as 12 MP JPEG, and about 10 GB if you shot them all at 48 MP HEIC. In 48 MP ProRAW, 1,000 photos would be around 100 GB, which is most of a 128 GB phone.
Does a higher megapixel count always mean a bigger file?
Almost linearly, as long as the format and quality stay the same. Double the megapixels and you roughly double the bytes: 12 MP HEIC is about 2.5 MB, 24 MP about 5 MB, 48 MP about 10 MB. Format swings the number much harder than resolution does, though. A 12 MP ProRAW file is bigger than a 48 MP HEIC.
How do I reduce photo file size without buying more storage?
Start with the format. Shoot HEIC instead of JPEG (Settings, then Camera, then Formats, then High Efficiency) and the whole library halves. Next, leave the Pro camera at 12 or 24 MP rather than 48 MP Max unless you are genuinely going to print or crop hard. Last, and this is the one that actually moves the needle, delete what you are storing for no reason: duplicates, burst frames, screenshots, the near identical shots of the same thing. That usually returns more gigabytes than the other two combined.