Every ratio, and what it costs you
Type two numbers and get the ratio, the decimal, the megapixels and the name it is sold under. Then drop an image in and see precisely how much of it a 9:16 frame eats.
- Recognises 1.85:1 and 2.39:1, not just 16:9
- Tells you what a crop throws away
- No upload, no account
The calculator works on typed numbers alone — you never need a file. Add one only if you want to see the frame on a real image.
Keeps the ratio readable. At 40, 1998×1080 comes back as 1.85:1 instead of 999:540.
aspect-ratio: 16 / 9;class="aspect-[16/9]"ffmpeg -i in.mp4 -vf "scale=1920:1080" out.mp4ffmpeg -i in.mp4 -vf "scale=1920:1080:force_original_aspect_ratio=decrease,pad=1920:1080:(ow-iw)/2:(oh-ih)/2" out.mp4magick in.jpg -resize 1920x1080^ -gravity center -extent 1920x1080 out.jpg<svg viewBox="0 0 16 9" preserveAspectRatio="xMidYMid meet"></svg>How it works
Pick the ratio
Type two dimensions, or choose one of the presets — screens, cinema, social feeds and paper sizes.
Add a picture, if you want one
Optional, and it never runs on its own: the file waits until you press the button that reads it.
Move the frame yourself
Drag to reposition, wheel to zoom, hold to compare with the original, Alt to flip between crop and letterbox.
Take the result with you
Copy the CSS, Tailwind or FFmpeg line, download the framed image, or send it straight to another tool.
Cinema ratios, not just 16:9
A plain greatest-common-divisor turns 1998×1080 into 999:540, which helps nobody. A bounded rational approximation gives you 1.85:1 and tells you how far off it is.
Says what a crop destroys
Fitting a 4000×3000 photo into 9:16 throws away 58% of it. That number is on screen before you commit, along with the letterbox bars for the other option.
Encoder-safe dimensions
H.264 rejects odd sides and hardware encoders prefer multiples of 4 or 8. Snap both sides to 2, 4, 8 or 16 and see how far the ratio drifted.
Nothing happens on drop
A dropped file just waits. Reading it, decoding it and drawing it only start when you press the button, and the manual path never needs a file at all.
You move the frame
Drag, zoom at the cursor, hold to compare against the original, Alt to preview the other fit mode, Ctrl+Z all the way back. Undo stores six numbers a step, not bitmaps.
Straight into the next tool
Send the framed image to CropSnap, CompressSnap, FormatFlow, WatermarkSnap or SocialBolt without downloading and uploading it again.
Frequently asked questions
Is anything uploaded?+
No. The calculations are plain arithmetic and the framing happens on a canvas inside your tab. Your image is decoded by the browser and exported by the browser. Turn the network off after the page loads and everything still works. The page does carry ads, which is the only thing here that talks to a server, and it never sees your file.
Why does 1998×1080 come out as 1.85:1 rather than 999:540?+
Because 999:540 is the exact answer and a useless one. Dividing by the greatest common divisor only helps when the result is small; beyond that we look for the best fraction with a denominator under the limit you set, which is how cinema ratios like 1.85:1 and 2.39:1 are actually written. When that fraction is not exact, the error is shown next to it.
What does the 'largest denominator' slider do?+
It caps how complicated the ratio is allowed to get. Low values force a simple, memorable pair and accept a small error; high values chase exactness and eventually give you back the raw fraction. Forty is a good middle ground: 16:9, 4:3, 2.39:1 and 1.414:1 all survive it.
Why would I snap dimensions to a multiple of 2, 4 or 8?+
H.264 cannot encode a frame with an odd width or height, and most hardware encoders and scalers are happiest on multiples of 4 or 8 because of how chroma is subsampled. Rounding shifts the ratio very slightly, so the drift is shown as a percentage and you can decide whether it matters.
What is the difference between cover and contain?+
Cover fills the frame and cuts off whatever hangs outside it. Contain fits the whole picture in and adds bars — letterbox above and below, pillarbox at the sides. The tool prints exactly what each costs: the percentage lost to the crop, or the thickness of the bars in pixels. Hold Alt to see the other one without changing anything.
Can I actually crop an image here, or only calculate?+
Both. Load an image, position the frame by dragging, zoom with the wheel, then download the result as PNG, JPEG or WebP at whatever output width you choose. If you would rather keep the whole picture, switch to contain and pick what fills the bars — black, white, transparent, or a blurred copy of the image itself.
Does dropping a file start anything?+
No, and that is deliberate. The file sits in a waiting state showing only its name and size. Nothing is decoded until you press the button that reads its dimensions, and you can remove it before that ever happens.
My HEIC photo from an iPhone will not open.+
HEIC decoding depends on the browser and the operating system, and most desktop browsers still refuse it. The same goes for some AVIF files. Convert it to JPEG or PNG first — FormatFlow in this suite does that locally too — and it will load here. You will get a clear message naming the format rather than a silent failure.
Where does the result go afterwards?+
Straight into another tool, if you want. The buttons under the editor hand the framed image over to CropSnap, CompressSnap, FormatFlow, WatermarkSnap or SocialBolt through your browser's own storage, so it never touches your Downloads folder on the way.