Aspect Ratio Calculator
Native Mac image sizing
Drop in an image, enter one dimension, and preview the exact output size, ratio, canvas, crop, and export format before you save.
Images stay on your Mac. Nothing is uploaded to us.
Product screenshots
Three real views of the Mac app: calculate the final size, preview the frame, then fine-tune what stays visible.
01
Drop in an image or enter dimensions. The app shows the original size, new size, ratio, decimal value, pixels, megapixels, and scale in one place.
02
See whether the image fits, crops, or needs canvas padding before you export.
03
Use Canvas Placement to anchor, crop, shrink, or position the image inside a fixed output frame. Blueprint Mode gives Pro users a darker grid view for this kind of detail work.
Image sizing should not require guesswork.
One wrong number can stretch a photo, break a layout, or crop the wrong part. Aspect Ratio Calculator keeps the math visible, shows the preview clearly, and exports the size you intended.
Lock the original proportions or choose a common ratio before you resize.
See the width, height, ratio, pixel count, megapixels, and scale in one place.
Copy the final size, CSS, HTML, Tailwind, Markdown, or your own saved format when you're done.
Original Size -> New Size -> Preview -> Copy / Export
You can see the original size, new size, preview, and export options without hunting through panels.
Drop in an image, or type in dimensions to read the real starting size.
Enter the target width or height, and let the app fill in the other side.
Preview the result before saving: image, canvas, crop, fit, ratio, scale, and final size.
Copy the size or export the image as PNG, JPG/JPEG, TIFF, or HEIC.
Resize Image vs Resize Canvas
Two different jobs, two different results. The app keeps the difference visible before you save.
Resize Image
Use this when the final file needs to be exactly the entered width and height, you want the image itself resized, and proportional scaling is what you need.
Resize Canvas
Use this when the outside frame is fixed, you need padding or crop control, and you want to place the image without stretching it.
Feature map
Calculate
Preview
Copy
Export
Mac workflow
Developer Copy
Copy the size in the format you actually need — no calculator tabs, no retyping, no almost-right values.
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.
Prepare hero images, Open Graph graphics, cards, thumbnails, and responsive images.
Resize screenshots for product pages, documentation, support articles, and app listings.
Place images into fixed frames while preserving the part of the photo that matters.
Resize listing photos, client graphics, blog images, and presentation images without stretching them.
Copy image sizes, HTML attributes, Markdown snippets, and CSS helpers without retyping them.
Check unit-aware details when the image needs to make sense beyond pixels.
Free and Pro
Free
Individual Pro Lifetime
Launch price: $9.99. Regular price: $14.99.
Family Pro Lifetime
Launch price: $14.99. Regular price: $19.99.
Support Development
Support purchases are a thank-you, not a feature gate.
Already bought? Existing paid-app customers get Pro automatically when the App Store can verify the old paid purchase. Family Add-On lets eligible Individual Pro and legacy paid users add Family Sharing for $4.99.
Native Mac utility
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.
For quick jobs, Quick Ratio lives in the menu bar so you can check dimensions, lock a ratio, copy CSS, HTML, Tailwind, or Markdown, and get back to what you were doing.
FAQ
Here's what the app does, what Pro adds, and what it intentionally does not try to be.
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.
Yes. The free version includes the core ratio calculator, image inspection, basic pixel details, built-in copy formats, Copy Output, and Copy Output Size.
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.
Family Sharing is available with Family Pro Lifetime and the Family Add-On. Individual Pro does not include Family Sharing.
No. If you bought the old paid version, Pro unlocks automatically when the App Store can verify your purchase.
PNG, JPG/JPEG, TIFF, and HEIC. HEIF is available when the macOS encoder supports it.
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.
No. It is intentionally focused on one image at a time: dimensions, ratios, preview, copy formats, and export.
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.
Ready to stop guessing image sizes?
Support and feedback
Include the original dimensions, the size you needed, and what happened. Please do not send sensitive files.
Review the Privacy Policy before sending personal details.