Aspect Ratio Converter
Converting between aspect ratios is not a resize — it is a choice about what to keep. You cannot change an image's ratio without either cropping part of it away or padding it with bars. This guide explains the three honest methods — crop, fit and fill — and shows what each does to real dimensions.
Convert a ratio without stretching
The one thing to avoid is stretching: forcing 16:9 footage into a 9:16 frame by squashing it distorts every face and circle in the shot. Because the source and target shapes are different, something has to give. You either crop the image down to the new shape, or pad it so the whole thing fits inside the new frame with bars. Everything below is one of those two ideas.
Fit, fill and crop explained
| Method | CSS | Result | You lose |
|---|---|---|---|
| Fit | object-fit: contain | Whole image visible, scaled to fit inside the frame | Screen space — bars appear |
| Fill | object-fit: cover | Frame filled edge to edge, no bars | The cropped-off edges |
| Crop | Manual crop | You pick the visible region by hand | Whatever falls outside |
| Stretch | object-fit: fill | Image distorts to match — avoid | Correct proportions |
Fit and fill are the same two choices web browsers make with object-fit. For copyable CSS that locks a container to a target ratio, use the CSS aspect-ratio calculator.
Worked examples
16:9 to 9:16 (landscape to vertical)
Starting from a 1920 × 1080 clip and converting to a 1080 × 1920 vertical frame:
- Fill / crop: keep a tall 1080 × 1920 slice from the centre. The frame is full, but you lose most of the left and right of the shot.
- Fit: the whole 16:9 frame shrinks to 1080 × 608 inside the 1080 × 1920 canvas, leaving large bars above and below.
This is the big one for repurposing video — the video aspect ratio guide covers reframing, and the 9:16 calculator sizes the target.
1:1 to 4:5 (square to portrait)
From a 1080 × 1080 square to a 1080 × 1350 portrait:
- Fit: the square sits at 1080 × 1080 with 270 px of bars split top and bottom.
- Fill: scale up to 1350 × 1350 and crop the sides back to 1080, losing 135 px on each side.
Size either target with the 1:1 and 4:5 calculators.
4:5 to 9:16 (portrait to full vertical)
From a 1080 × 1350 feed post to a 1080 × 1920 Story or Reel:
- Fit: the 4:5 image sits at 1080 × 1350 with 570 px of bars top and bottom.
- Fill: scale up to 1536 × 1920 and crop the sides to 1080, losing 228 px on each side.
The Instagram calculator has presets for both shapes.
Which method should you use?
- Fill or crop when the frame must be full and reframing around the subject is fine — the right choice for most social video and feed posts.
- Fit when losing any part of the image is worse than showing bars — diagrams, screenshots, artwork and product shots where the edges matter.
- Crop by hand when the subject is off-centre or moves, so an automatic centre crop would cut it off.
- Never stretch. If a tool only offers stretch, add a background or bars instead.
Calculate the target dimensions
Pick your target ratio and enter one side to get the other, then crop or pad to it. Start with the aspect ratio calculator, or jump to the 16:9 and 9:16 calculators for the most common conversions.
Open the calculatorFrequently asked questions
Can I change aspect ratio without stretching?
Yes. Instead of stretching, crop the image to the new ratio or pad it with bars. Stretching is the only method that distorts the picture, so avoid it.
What is the difference between fit and fill?
Fit (contain) scales the whole image to sit inside the frame and may add bars. Fill (cover) scales the image to cover the frame and crops whatever overflows.
How do I convert 16:9 to 9:16?
Crop the wide 16:9 frame down to a tall 9:16 window around your subject, or place it on a 9:16 canvas with a background. Do not stretch it.
Which method is best for social media?
Fill or crop to the platform's ratio so the frame is full, and reframe around your subject. Use fit only when keeping the entire image matters more than filling the screen.