HEIC, JPEG and print quality: what actually matters

The question people ask before uploading is whether HEIC will print as well as JPEG, and whether they should convert. The honest answer is that the format is the least important thing about a phone photo in print. What matters is how many pixels the file has, whether it has been through a chat app, and whether it is a photograph at all. This article takes those in order.

HEIC versus JPEG

Both are lossy compressed formats. HEIC, which iPhones have shot by default since 2017, uses a newer codec that stores a photo of the same quality in roughly half the space of a JPEG. That is the whole difference from a printing point of view: the pixels are the same, the camera's processing is the same, and the EXIF block with capture time, GPS and orientation is the same.

Upload HEIC as it is. MakeAlbum accepts JPEG, HEIC and HEIF, PNG, WebP and AVIF up to 50 MB per file. HEIC is converted on the server, and the EXIF block is read from the untouched original before conversion, so nothing is lost. Converting on your own computer first adds a step and, with some tools, drops the metadata that orders the book and splits it into chapters. The preparation guide covers the rest of what not to bother with, and the iPhone photo book page has the upload route from the phone.

PNG, WebP and AVIF are accepted too. None of them is better or worse for print than the others at the same pixel count.

What 300 dpi means on this page

Print resolution is quoted in dots per inch, and 300 dpi is the conventional threshold for photographic quality at reading distance. A MakeAlbum page is 300 mm square, which is 11.8 inches, so a full page at 300 dpi is about 3,540 pixels on each side. A frame that runs across both pages of a spread covers 600 mm and wants about 7,090.

A 12 megapixel phone photo is around 4,032 × 3,024 pixels. On a single page, with the long edge along the 300 mm side, that is roughly 340 dpi: above the threshold with room to spare. Across a full spread it is about 170 dpi, which prints acceptably at the distance you hold an open book and is why the layout engine reserves the full-spread placement for the strongest frames rather than using it on every spread. Phones that shoot 24 or 48 megapixel frames when the light allows have more headroom still.

For a half-page slot or a grid cell, the numbers halve. A 1,600-pixel file is comfortable in a small slot and soft on a full page. That is the number to keep in mind for the next section.

How the print file is made

When you approve an album, the print-ready PDF is rendered from the original files, not from the previews in the editor. Each photo is fetched from storage, auto-rotated according to its orientation tag, and resized so that its long edge is at most 3,600 pixels, which is a full 300 mm page at 300 dpi with a little margin. It is never enlarged: a smaller original stays at its own size, because scaling up adds pixels without adding detail. Photos that only appear in smaller slots are rendered at the size the slot needs, with a floor of 1,800 pixels, which keeps the file sensible without costing anything visible. The result is embedded as a high-quality JPEG.

Two consequences follow. A photo above 3,600 pixels on its long edge gains nothing from being larger; a 48 megapixel frame prints the same as a 12 megapixel one on a single page. And a photo well below that is printed as it is, so the softness that results is the original's, not the pipeline's. A sharp full page needs a file with enough pixels, which for a phone photo means the original rather than a copy.

The thing that actually degrades photos: chat apps

Far more phone photos are ruined for print by WhatsApp than by any file format. When a photo is sent as a photo in WhatsApp, it is recompressed and downscaled, typically to around 1,600 pixels on the long edge, and its EXIF block is stripped, so the capture time, GPS and camera are gone. The file that arrives is named for the day it was received, not the day it was taken. Messenger, Instagram direct messages and most other chat apps do something similar; "small" and "medium" options in email do it deliberately.

A 1,600-pixel copy is fine in a small slot and poor on a full page, and with no capture time it cannot be placed in the right chapter on its own. The fix is at the source. Ask for photos to be sent as a document or file rather than as a photo, which keeps the original quality and EXIF in WhatsApp; or by AirDrop, an iCloud link, a Google Photos share or any transfer that moves the file rather than a preview of it. If the chat copy is all that exists, use it in a small slot, not as a chapter opener. The wedding guest photos article goes through how the ordering copes when most of a set has lost its dates.

Cloud services are different. iCloud Photos and Google Photos in Original quality keep the file as the camera made it. Google's Storage saver setting recompresses on upload and caps resolution at 16 megapixels, which is still ample for a page. iCloud Shared Albums, unlike the main library, reduce photos to 2048 pixels on the long edge. The Google Photos and iCloud article covers the exports.

Screenshots, zoom and other non-photos

A screenshot has the resolution of the screen it was taken on, around 1,200 × 2,600 pixels on a recent phone, no EXIF, and a tall aspect ratio. It is set aside automatically on upload, along with photos of documents, boarding passes and receipts, by filename, by the EXIF software field and by content. They stay in the tray if you want one in the book, and a small slot is where it belongs.

Digital zoom is a crop. A 10× zoom on a phone without a matching lens is a small section of the sensor scaled up, and it has the pixels of that section. A 12 megapixel frame at 5× digital zoom has the detail of a frame under one megapixel. Treat zoomed frames as small-slot material.

Live Photos upload as their still frame. Portrait mode photos and edits made in the Photos app are baked into the file and print as you see them. A heavily cropped photo has fewer pixels than the original; if it is meant to go full-page, upload the uncropped version and let the layout crop it to the square instead.

A quick check before uploading

Open a photo's information in Photos or Google Photos and look at the pixel dimensions. Above 3,000 pixels on the long edge, it will print on a full page. Around 1,600, it will print well in a half-page slot or a grid. Below 1,000, it is a small-slot photo or a photo to leave out. If the dimensions look low for a photo you know was taken on a good phone, you have a copy rather than the original, and it is worth finding the original.

What to do

Upload originals, in whatever format the phone produced. Do not convert HEIC. Get chat-app photos re-sent as files. Let the filter set aside the screenshots. Then let the curation pick the strongest frames for the full pages, and use the editor to move anything soft into a smaller slot. Matte or glossy paper is a separate choice, made in the editor, and the format article explains it; the how it works page has the rest of the sequence from upload to print.