Anamorphic desqueeze calculator

How to calculate anamorphic desqueeze

An anamorphic lens compresses the horizontal field of view into the recorded frame. Desqueezing restores the intended proportions. Enter the dimensions of the actual recording, not a monitor preview, and the horizontal squeeze factor specified for your lens and recording setup.

1. Select a recorded resolution or enter its width and height.
2. Choose a lens factor such as 1.33x, 1.5x, 1.6x, 1.8x or 2x. Use Custom for a different value.
3. Expand the width to retain vertical sampling, or reduce the height for a smaller output raster.
4. Use the even-pixel export dimensions in your editor or review the generated FFmpeg command.

Results update as you type. No file is needed and calculations run locally in the browser. Check whether your camera, proxy workflow or editor has already applied a desqueeze before using these dimensions.

Anamorphic aspect ratio formula

For recorded width W, height H and horizontal squeeze S:

• Desqueezed aspect ratio = (W ÷ H) × S
• Expand width: output = (W × S) × H
• Reduce height: output = W × (H ÷ S)

Both methods give the same ideal frame shape. For example, 3840 × 2160 with a 1.6x lens becomes 6144 × 2160 when expanding width, or 3840 × 1350 when reducing height. Both have a 2.8444:1 ratio. Expansion creates additional horizontal samples, not new captured detail. Reducing height discards vertical samples and can be more convenient for a smaller delivery file.

The model assumes the entered raster needs one horizontal correction by S and that the output uses square pixels. Non-square source pixel metadata, camera-specific readout modes and prior transforms must be accounted for in your editing workflow.

Common squeeze factors on a 16:9 recording

Recording shape matters as much as lens squeeze. A 4:3 recording with 2x squeeze gives 2.6667:1, while a 3:2 recording with 1.6x gives 2.4:1. Do not assume every anamorphic setup produces 2.39:1.

Desqueeze, then choose your delivery frame

Correcting stretched proportions and framing a final delivery are different operations. If your desqueezed image is wider than the delivery ratio, fill the frame by cropping the sides or preserve the full image with letterboxing. Neither choice is automatically part of desqueeze.

For a 6144 × 2160 image delivered at exactly 2.39:1, a full-height mathematical crop is 5162.4 × 2160 before pixel rounding. Use the crop loss calculator to compare the removed area. To keep all the scene, use the letterbox and pillarbox calculator after desqueezing.

Why even dimensions?

The command uses H.264 with 4:2:0 pixel format, so this tool rounds both output dimensions to positive even integers. Odd source dimensions may therefore change by one pixel even on the nominally preserved axis. The result shows the resulting ratio change; very small inputs can have a significant rounding error. Ideal dimensions are also shown when you need the unrounded calculation.

Using the FFmpeg command safely

The generated command scales the raster with Lanczos resampling, sets the output sample aspect ratio to 1:1, and encodes H.264 video at CRF 18. It copies the audio stream unchanged. You need FFmpeg installed locally; this website does not run the command.

Check that the input dimensions match your entry and that no prior desqueeze is active. A metadata-only pixel-aspect-ratio change is not the same as this raster-resampling export. For rotated clips, confirm the dimensions after your editor or FFmpeg applies rotation. Use a new output filename and review a short test clip before a full export.

CRF 18 is a starting point, not a lossless setting. Large outputs may exceed a player or platform's supported resolution; reduce the output to a suitable delivery size if needed. If copied audio is incompatible with MP4, replace -c:a copy with -c:a aac -b:a 192k. The command is a basic single-video export, not an archival workflow preserving every track or metadata field.

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