No stretched images
Lock the original proportions or choose a common ratio before you resize.
Native Mac app for image sizing
Get the image size right before you export.
Drop in an image or enter the dimensions yourself. Aspect Ratio Calculator keeps the proportions straight, previews the result, and lets you copy or export the final size as PNG, JPG/JPEG, TIFF, or HEIC.
Images stay on your Mac. Aspect Ratio Calculator processes images locally and does not upload them to us.
- macOS 15+
- Free to download
- Optional Lifetime Pro
- PNG · JPG/JPEG · TIFF · HEIC
- Mac share sheet supported
- Copy for CSS, HTML, Tailwind & Markdown
Real app screenshots
A Mac workspace for getting image sizes right.
These current screenshots show the calculator, preview, metadata chips, resize/canvas controls, settings, and Canvas Placement window working together.
Image sizing should not require guesswork.
One wrong number can ruin the image.
One wrong dimension can stretch a photo, break a layout, crop the wrong part of the image, or send the wrong file to a client. Aspect Ratio Calculator keeps the math visible, shows the preview clearly, and exports the size you intended.
No mystery math
See the width, height, ratio, pixel count, megapixels, and scale in one place.
No retyping values
Copy the final size, CSS, HTML, Tailwind, Markdown, or your own saved format when you're done.
Original Size -> New Size -> Preview -> Copy / Export
A simple way to go from original size to final image.
You can see the original size, new size, preview, and export options without hunting through panels.
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01
Original Size
Type in dimensions, or drop in an image to read its real size.
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02
New Size
Enter the width or height, and let the app fill in the other side.
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03
Preview
Preview the image, canvas, crop, fit, ratio, scale, and final size before exporting.
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04
Copy / Export
Copy the values you need, export the image, or send it through the Mac share sheet.
Everything you need to size, preview, copy, and export an image.
Image-sizing tools that stay out of your way.
Aspect ratio calculator
Calculate the missing width or height, plus ratio, pixels, scale, and megapixels.
Built-in presets
Start with common ratios for square, photo, widescreen, vertical, print, and cinema layouts.
Image inspection
Drop in an image to see its real pixel size and basic details.
Resize Image
Resize the actual image to the new width and height.
Resize Canvas
Place an image inside a new frame without stretching it.
Canvas placement
Anchor the image, shrink it to fit, or fine-tune where it sits in the canvas.
Developer Copy
Copy ready-to-use CSS, HTML, Tailwind, Markdown, size notes, or custom Pro templates.
Menu bar or window
Use it as a regular Mac window or keep it handy in the menu bar.
PNG, JPG/JPEG, TIFF, and HEIC export
Export PNG, JPG/JPEG, TIFF, or HEIC. HEIF is available when your Mac supports it.
Save-panel export controls
Choose the format when you save, and adjust quality for compressed formats like JPG or HEIC.
Native macOS sharing
Send the resized image through the Mac share sheet without exporting it first.
Resize Image vs Resize Canvas
Resize the image, or resize the frame.
Resize Image
Change the image itself to the new size.
Use this when the final file needs to be exactly the width and height you entered.
- Exact final dimensions
- Preserves proportions when locked
- Export as PNG, JPG/JPEG, TIFF, or HEIC
Resize Canvas
Place the image inside a new canvas or frame without stretching it.
Use this when the outside frame is fixed and the image needs to fit, crop, or sit in a specific spot.
- Shrink-to-fit option
- Nine anchor positions
- Fine-grained canvas placement
Resize & Export
Export or share the exact result
When the preview looks right, export it as PNG, JPG/JPEG, TIFF, or HEIC. You can choose the format and quality in the save panel, or send the result through the Mac share sheet.
PNG
JPG/JPEG
TIFF
HEIC
HEIF*
* HEIF availability depends on macOS encoder support.
PNG and TIFF support transparent canvas backgrounds. JPEG exports with a white background.
Developer Copy
Copy the values your project actually needs.
When the size is right, copy it in the format you actually use: CSS, HTML, Tailwind, Markdown, size notes, documentation rows, or your own Pro template.
- Copy visible size details with one click.
- Copy the final output size from the bottom bar.
- Save your own copy templates with Pro.
aspect-ratio: 16 / 9;<img src="hero.jpg" width="1920" height="1080" alt="">aspect-[16/9]Made for the moments when the exact size matters.
For the everyday image jobs that still need to be right.
Websites and landing pages
Prepare hero images, Open Graph graphics, cards, thumbnails, and responsive images.
App and product screenshots
Resize screenshots for product pages, documentation, support articles, and app listings.
Social posts and ads
Place images into fixed frames while preserving the part of the photo that matters.
Real estate and business listings
Resize listing photos, client graphics, blog images, and presentation images without stretching them.
Developer documentation
Copy image sizes, HTML attributes, Markdown snippets, and CSS helpers without retyping them.
Print-aware prep
Check unit-aware details when the image needs to make sense beyond pixels.
Free and Pro
Start free. Upgrade when you want saved ratios, custom templates, and more control.
Free Core Utility
Free includes the core calculator, image inspection, built-in copy formats, output size copying, and a clear preview of what Pro adds.
- Calculate missing width or height
- Inspect image dimensions
- View ratio, pixels, scale, and megapixels
- Preview export controls
- Use built-in copy formats
- Copy built-in output formats
- Copy Output Size
- Preview Pro controls before upgrading
Pro Lifetime
Pro adds saved ratios, custom copy templates, advanced unit options, iCloud sync, and more control over resize, canvas, and export tools.
- Saved custom ratios
- Custom copy templates
- Advanced unit conversions
- Configurable metadata chips
- iCloud settings sync
- Advanced resize, canvas, and export workflows
Individual Pro Lifetime unlocks Pro for one Apple Account. Launch price: $9.99. Regular price: $14.99.
Family Pro Lifetime supports Mac App Store Family Sharing. Launch price: $14.99. Regular price: $19.99.
Family Add-On lets eligible Individual Pro and legacy paid users add Family Sharing for $4.99.
Support Development purchases such as Coffee, Latte, and Double Shot are optional ways to support development. They do not unlock features.
Existing paid-app customers get Pro automatically when the App Store can verify the old paid purchase.
Native Mac utility
A focused Mac utility, not a bloated editor.
Aspect Ratio Calculator is built to feel like a Mac app: drag and drop, a focused window, optional menu bar mode, and controls that make sense without a tutorial.
- Supports macOS 15.0 and later
- Uses Liquid Glass styling on macOS 26 when available
- Falls back to native controls on macOS 15 through macOS 25
- Works as a regular window or menu bar utility
FAQ
A few things worth knowing before you download.
Here's what the app does, what Pro adds, and what it intentionally does not try to be.
Is Aspect Ratio Calculator a full image editor?
No. It is a focused tool for sizing images, preserving proportions, previewing the result, copying useful values, and exporting the final image. It is meant to sit alongside apps like Photoshop, Figma, Canva, Pixelmator, and Preview - not replace them.
Can I use it for free?
Yes. The free version includes the core ratio calculator, image inspection, basic pixel details, built-in copy formats, Copy Output, and Copy Output Size.
What does Pro unlock?
Pro adds saved custom ratios, custom copy templates, advanced unit conversions, configurable metadata chips, iCloud settings sync, and more control over resize, canvas, and export tools.
Does it support Family Sharing?
Family Sharing is available with Family Pro Lifetime and the Family Add-On. Individual Pro does not include Family Sharing.
I bought the old paid app. Do I need to buy Pro again?
No. If you bought the old paid version, Pro unlocks automatically when the App Store can verify your purchase.
Which export formats are supported?
PNG, JPG/JPEG, TIFF, and HEIC. HEIF is available when the macOS encoder supports it.
Can I export HEIC or HEIF files?
Aspect Ratio Calculator supports HEIC export, and HEIF is available when the macOS encoder supports it. The same export workflow also supports PNG, TIFF, and JPG/JPEG files.
Can I share the resized output directly?
Yes. The bottom-bar Share action renders the current output and opens the native macOS share sheet, so you can send the result through the sharing options available on your Mac.
Can I control image quality when exporting?
The save panel includes export options for format selection and lossy image quality where the chosen format supports compression.
Does it do batch export or AI editing?
No. It is intentionally focused on one image at a time: dimensions, ratios, preview, copy formats, and clean export.
Where do I get support?
Use the contact form on this site and include the image size, export format, purchase question, or sizing problem you need help with. Please do not send sensitive files through the form. You can also review the Privacy Policy and Terms of Service before sending personal details.
Get the image size right before you export.
Calculate the ratio, preview the result, copy the values, and export the image at the size you meant to use.
Support and feedback
Tell us what you are trying to size.
Send a note if you need help, have feedback, or keep running into an image-sizing problem that wastes time.
Please do not send sensitive files through this form. Review the Privacy Policy before sending personal details.