{{ summaryTitle }}

{{ summaryValue }}

{{ summaryLine }}

Frame · {{ cropModeLabel }} Crop · {{ cropDimensionsLabel }} Privacy · Local only
Drop or browse for MP4, MOV, WebM, or MKV, or load the short generated demo clip.
{{ sourceDropTitle }}
{{ sourceDropLine }}
One video · 50 MB · 2 minutes · up to 1080p

{{ sourceStatus }}

Start freeform or load a common delivery ratio, then refine the exact rectangle.
The rectangle is a stationary crop for the whole clip; this tool does not track a moving subject.
{{ cropDimensionsLabel }}
px
px
px
px

X and Y locate the upper-left corner. Width and height define the pixels kept in every frame.

{{ firstIssueMessage }}

Each nudge moves {{ normalizedNudge }} even source pixels.

{{ workflowMessage }}

Letters, numbers, spaces, hyphens, and underscores only; opening Advanced does not change the crop.
Use an even value from 2 to 200 source pixels.
px

Cropped video

Play the complete verified MP4 before using it in place of the source.
No cropped file yet Choose a source, review the rectangle, and run the local crop. The planning artifacts remain available in the other tabs.

The chart renderer is unavailable. The same retained-area values remain in the crop receipt.

SignalValueMeaningCopy
{{ row.label }}{{ row.display }}{{ row.detail }}

Delivery guidance

{{ item.title }}

{{ item.detail }}

Field of View Calculator Plan camera framing from active sensor size and focal length at a chosen distance with angle-of-view math, target-fit checks, and comparative lens sweeps.
Timecode Duration Calculator Calculate frame-accurate timecode spans with drop-frame validation and endpoint rules, then add 24-hour wrap or pull handles when needed.
Video Bitrate Storage Calculator Plan video storage from bitrate and recording duration, including multiple cameras and copies plus headroom and whole-drive capacity checks.
Video Call Sheet Generator Build a one-day video call sheet with staggered crew calls, schedule conflict checks and calendar-ready events for the production day.

Cropping changes which part of every video frame remains visible. It can turn a landscape recording into a vertical social clip, remove empty edges, or keep attention on one region without shortening the timeline. The crop rectangle has four parts: its left and top offsets locate the rectangle, while its width and height set the output frame.

A delivery ratio such as 16:9, 9:16, 1:1, or 4:5 describes the rectangle's shape, not its pixel count or picture quality. A 9:16 crop could be 540 × 960 or 1080 × 1920 pixels. Both have the same shape, but the larger frame retains more samples and normally needs more data to encode.

Stationary crop
The same rectangle applies from the first frame to the last.
Aspect ratio
Width divided by height, used to match a display or publishing slot.
Retained area
The crop's pixel area as a percentage of the decoded source-frame area.

A fixed rectangle works best when the important subject stays inside one region. It does not follow a person, ball, cursor, or camera pan. Scrubbing only the opening frame is therefore risky: a subject that is centered at the start can leave the crop later.

Cropping a video also requires a new encode. That makes the result a delivery copy rather than a lossless edit master. Keep the original, review the complete output, and treat frame coverage as a composition clue rather than a measure of visual quality.

How to Use This Tool:

Choose the destination shape first, then position one rectangle that remains safe for the whole clip.

  1. Choose one Source video in MP4, MOV, WebM, or MKV form. The browser must be able to read its video track, and the file must stay within the displayed size, duration, and resolution limits.
  2. Select a Frame shape. Use a custom rectangle for exact dimensions or load a delivery ratio as a starting point.
  3. Set X and Y for the left and top edges, then set W and H for the retained width and height. Dragging and nudge controls change the same rectangle.
  4. Start the local crop. If a boundary or even-pixel warning appears, move or resize the rectangle until every edge stays inside the source frame.
  5. Play and scrub the complete Cropped video. Check the reported dimensions, duration, audio policy, and retained area before downloading the MP4.

Interpreting Results:

The retained-area percentage says how much of the source-frame area remains. It does not reveal whether the crop cuts off a moving subject or whether the re-encoded picture looks good. A result below 35% receives a tight-crop warning because small framing errors become more consequential when most of the original view has been removed.

  • Confirm that the reported output width and height match the intended delivery slot.
  • Scrub scenes with the most movement and inspect all four edges, not only the preview frame.
  • Listen for audio when the source contains sound and the output is expected to preserve it.
  • Keep the original if the video may be cropped, graded, or encoded again.

A verified compatibility result can be video-only at 12 frames per second. Use that path only for a silent clip where reduced motion cadence is acceptable; otherwise rerun in a secure current browser that supports the normal video and audio encode path.

Technical Details:

Crop geometry is evaluated in decoded display pixels. The origin is the source frame's top-left corner, so increasing the horizontal offset moves the rectangle right and increasing the vertical offset moves it down. Width and height describe the output dimensions directly.

Formula Core:

Aspect ratio compares the crop's width with its height, while retained area compares the crop rectangle with the complete source frame.

rc=WcHc P=100×Wc×HcWs×Hs

Here, Wc and Hc are crop width and height, and Ws and Hs are source display width and height, all in pixels. For a 100 × 178 crop from a 320 × 180 frame, the retained area is about 30.9%.

Transformation Core:

The browser reads the primary video track and any primary audio track, verifies the display dimensions, applies the same rectangle to every frame, and writes H.264 video into an MP4. When source audio is present on the normal path, it is transcoded to AAC. The finished file is reopened and accepted only when it contains playable video, has the reviewed dimensions, follows the source audio policy, and keeps duration within 0.15 seconds or 5% of the source duration, whichever tolerance is larger.

RuleAccepted boundaryReason
Source file256 bytes to 50 MiBBounds browser memory and processing work.
Duration0.1 to 120 secondsRejects unusable or overly long local jobs.
Display frameEach dimension at most 1920 px and total area at most 2,073,600 pxKeeps decoded frame work within the supported range.
Rectangle valuesWhole, even pixel values; width and height at least 2 pxMaintains H.264 chroma alignment.
BoundsX + W ≤ source width and Y + H ≤ source heightPrevents sampling outside the decoded frame.
Ratio presetAbsolute difference from the selected ratio ≤ 0.01Allows even-pixel rounding without accepting the wrong shape.

Privacy and Limitations:

The source bytes, decoded frames, and generated MP4 remain in memory in the current browser tab and are not uploaded. They disappear when the source is replaced or the page closes.

  • The rectangle never tracks motion and does not add pixels outside the source.
  • The job does not trim time, resize after cropping, combine clips, add effects, or process a batch.
  • H.264 and AAC encoding is lossy, and codec support varies by browser.
  • Displayed rotation and intrinsic dimensions can differ in unusual source files, so the decoded preview and verified output dimensions remain the practical reference.

References: