What is the difference between letterboxing and pillarboxing?

Letterboxing occurs when a wider video (like 21:9 or 2.39:1) is placed on a taller screen (like 16:9), adding black bars on the top and bottom. Pillarboxing occurs when a narrower video (like 4:3) is placed on a wider screen (like 16:9), adding black bars on the left and right sides.

What causes windowboxing (postage-stamping)?

Windowboxing happens when a video has black bars on all four sides. This occurs when 4:3 content that was previously letterboxed inside a 16:9 container is subsequently played back on a 4:3 screen or pillarboxed again by a video platform.

How many pixels are the black bars on 2.39:1 cinema footage in a 4K 16:9 frame?

In a standard 4K UHD 16:9 frame (3840x2160), a 2.39:1 cinema master occupies 3840x1607 pixels, leaving 553 total pixels of vertical letterboxing: approximately 276 pixels on top and 277 pixels on the bottom.

Should I crop my video or add black bars?

It depends on composition intent. Letterboxing preserves 100% of the director's original camera framing without losing headroom or edge action. Cropping (fill) eliminates black bars but permanently cuts off up to 33% of your visual scene.

How do I add black bars in FFmpeg without re-encoding?

To add padding in FFmpeg, use the scale and pad filter: ffmpeg -i input.mp4 -vf "scale=1920:1080:force_original_aspect_ratio=decrease,pad=1920:1080:(ow-iw)/2:(oh-ih)/2" output.mp4.

Creators & Video100% Client-Side Local Execution•Updated 2026

Aspect Ratio Letterbox, Pillarbox & Video Padding Dimension Calculator

Name: Aspect Ratio Letterbox, Pillarbox & Crop Dimension Calculator
Author: AnshuTechy

Calculate exact pixel black bars (letterbox/pillarbox), scale factors, target canvas padding, and center-crop coordinates when fitting footage across 16:9, 21:9, 4:3, and 9:16 displays.Documentation & FAQs ↓

Aspect Ratio Letterbox, Pillarbox & Crop Dimension Calculator — Interactive Console

Runs locally in your browser • Instant output

Display ArtifactPillarbox (Left & Right)Zero geometric stretch

Black Bar Thickness320pxLeft & Right padding

Source Aspect Ratio1.78 : 11920 × 1080

Target Container21:9Ratio: 2.37:1

Source Preset

Target Display Aspect

Scaling Methodology

Display Viewport Visual Simulator

Active Video Image (1920×1080)Black bars preserve original framing

Step-by-Step Instructions

4 Steps to Completion

1Phase 1

Enter your source video resolution (e.g., 1920x1080, 3840x2160, 1440x1080, or 2560x1440).

2Phase 2

Select or input your destination container or display screen dimensions (e.g., 2560x1080 21:9 or 1080x1920 9:16).

3Phase 3

Choose your scaling mode: 'Fit (Letterbox/Pillarbox Padding)' or 'Fill (Center-Crop Overhang)'.

4Phase 4

Copy the exact pad dimensions, scaling percentage, and ready-to-use FFmpeg pad syntax.

Practical Use Cases & Real-World Scenarios

Cinema 2.39:1 to 16:9 Television Mastering

Determine exact 138px letterbox matte bars required to master 2.39:1 scope widescreen movies into 1080p and 4K UHD standards.

Retro 4:3 Gaming & Archival Video Upscaling

Calculate 240px pillarbox side borders when displaying 4:3 game captures inside modern 16:9 YouTube streams.

Ultrawide 21:9 Video Player Embedding

Fit 16:9 gaming clips onto 3440x1440 or 5120x1440 ultrawide monitors without distortion or accidental image stretching.

Related Editorial Guide on AnshuTechy7 Roles of Video Converter Tools in Video Editing Workflows

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100% free, private in-browser utility with zero server uploads.

Aspect Ratio Letterbox, Pillarbox & Video Padding Dimension Calculator

Display Viewport Visual Simulator

Step-by-Step Instructions

Practical Use Cases & Real-World Scenarios

Letterbox vs Pillarbox Detection

Pixel-Perfect Padding Measurements

Center-Crop vs Fit-to-Screen Modes

FFmpeg & CSS Code Snippets

Frequently Asked Questions

7 Roles of Video Converter Tools in Video Editing Workflows

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