Use Preview Convert Images? How-To Guide

Yes, you can convert image formats directly in the Preview app on a Mac. You open the image, choose File > Export, pick a format like JPEG, PNG, HEIC, or TIFF, and save. This built-in tool handles single images and batches of files without any extra software.

What Preview Can and Cannot Convert

Preview is Apple’s default image and PDF viewer on macOS. Its conversion feature is reliable for common raster formats: JPEG, PNG, TIFF, GIF, HEIC, BMP, and PDF (for images). It can also convert a PDF’s pages into image files. However, Preview does not export to SVG, WebP, or RAW camera formats. For those, you need a dedicated converter or a graphics editor. Also, Preview cannot convert a video file or an audio file; it only handles still images and PDFs.

How to Convert a Single Image

Converting one image takes about ten seconds. Follow these steps:

1. Double-click the image file to open it in Preview. If it opens in another app, right-click the file, choose Open With, and select Preview.
2. Go to the menu bar and click File > Export.
3. In the export window, click the Format drop-down menu and choose your target format (JPEG, PNG, HEIC, TIFF, etc.).
4. Adjust the quality slider if the format supports it (JPEG and HEIC do).
5. Pick a location and click Save. The original file stays untouched; Preview creates a new file.

If you want to replace the original with the new format, hold the Option key while clicking File, and the menu item changes to Export As. That saves the new file and deletes the original after confirmation.

How to Convert Multiple Images at Once

Batch conversion saves time when you have a folder of photos. Here is the method:

1. Select all the images in Finder. You can click one, then hold Shift and click the last one to select a range, or hold Command and click individual files.
2. Right-click any selected file and choose Open With > Preview. All images open in a single window with a sidebar showing thumbnails.
3. In Preview, select all thumbnails by pressing Command + A (or Edit > Select All).
4. Go to File > Export Selected Images.
5. Choose the format, set a quality if available, and click Choose to select an output folder. Preview will create new files with the same base names but the new extension.

This method works for mixed formats too. You can select three JPEGs and two PNGs and export all five as HEIC in one step.

What Each Format Is Best For

Choosing the right format matters more than the conversion itself. Here is a quick guide:

• JPEG – Best for photos shared online or via email. It compresses well but loses quality each time you save. Use for web images where file size matters.
• PNG – Best for screenshots, logos, and graphics with text. It supports transparency and lossless compression, but files are larger than JPEG.
• HEIC – Best for saving space while keeping high quality. It is the default format for iPhone photos, but some Windows apps and websites cannot open it.
• TIFF – Best for print work and archiving because it is lossless and widely supported by publishing software. Files are very large.
• GIF – Best for simple animations or images with flat colors. It only supports 256 colors, so photos look poor.
• PDF – Best when you need a document that prints consistently or that you want to share as a single page. Preview can export an image as a PDF.

Common Problems and How to Fix Them

Users often run into a few issues when converting. Here are the typical ones:

• Export option is grayed out. This happens when you have not selected any image. Click the thumbnail in the sidebar first, then try File > Export.
• HEIC not appearing in the format list. This can happen on older macOS versions. Update your system, or convert to JPEG first and then use a third-party tool for HEIC.
• Transparent background turns black or white. JPEG does not support transparency. If you need to keep transparency, use PNG or TIFF.
• Batch export only converts one image. Make sure you selected all thumbnails with Command + A before choosing Export Selected Images. If you only click one, Preview exports just that one.
• File size is still huge after converting to JPEG. Lower the quality slider in the export window. A quality of 70-80% is usually a good balance for web use.

Preview vs. Online Converters vs. Dedicated Apps

Preview is not the only way to convert images. Here is how it compares to the alternatives:

• Preview – Free, offline, fast, and private. It does not upload your files anywhere. The main downside is limited format support (no WebP or SVG).
• Online converters (like CloudConvert or Convertio) – Support many more formats and work in any browser. But you must upload your image to a third-party server, which raises privacy concerns. Free tiers often have file size limits and wait times.
• Dedicated apps (like GIMP, Photoshop, or ImageOptim) – Offer advanced controls like color profiles, compression presets, and batch scripting. They are overkill for a simple format change but necessary for professional workflows.

For most everyday conversions, Preview is the best choice because it is already on your Mac and does not require an internet connection.

Does Converting Reduce Image Quality?

It depends on the source and target format. Converting from a lossless format (PNG, TIFF) to a lossy format (JPEG, HEIC) will reduce quality because the new file discards data. Converting from JPEG to PNG does not improve quality; the original JPEG artifacts are already baked in. Converting from a lossy format to another lossy format (JPEG to HEIC) causes a second generation of quality loss. If you need to preserve the highest possible quality, keep the original file and only convert copies. Preview does not upscale or downscale the image unless you change the dimensions in the export window, so the pixel count stays the same.

Frequently Asked Questions

Can Preview convert a PDF to a JPEG? Yes. Open the PDF in Preview, select the page you want (or all pages), then use File > Export and choose JPEG. Each page becomes a separate JPEG file. If you select all pages, Preview will create one JPEG per page.

Does Preview support WebP conversion? No. macOS can display WebP images in recent versions, but Preview cannot export to WebP. You will need a third-party converter or a browser extension for that format.

Will converting change the file dimensions? No, unless you manually change the width or height in the export dialog. Preview keeps the same pixel dimensions by default. You can also scale the image down during export, but you cannot upscale without losing sharpness.

Is there a way to convert without opening Preview? Yes. In Finder, you can use a Quick Action if you set one up, or use the command line with sips. For example, typing sips -s format png image.jpg --out image.png in Terminal converts a JPEG to PNG. That is faster for batch jobs but requires some comfort with the terminal.

Why is my converted PNG file so large? PNG uses lossless compression, which preserves every pixel. Photos with lots of detail and color gradients do not compress well in PNG, so file sizes can be several times larger than a JPEG. If size is a concern, use JPEG or HEIC instead.

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