4:3 Aspect Ratio Calculator
This calculator works out the matching width or height for the 4:3 aspect ratio, the proportion used by older televisions, computer monitors, projectors and many print layouts, where every four units of width correspond to three units of height. Choose whether you want to solve from a known width or a known height, enter that figure in any unit such as pixels, centimetres, inches or millimetres, and optionally select a unit label purely for display. You can also pick from common 4:3 presets, including 640x480 VGA, 1024x768 XGA and 2048x1536 QXGA, to auto-fill the fields. The calculator instantly returns the matching width and height, the diagonal measurement worked out using the Pythagorean theorem, and the total pixel area, alongside a calculation breakdown showing the exact formula applied and a ratio verification check confirming the result truly sits at 4:3. A table of common 4:3 resolutions and their typical uses, plus a scaled visual preview of the rectangle, help you see how your figures compare to standard formats. Use it when sizing screens, video frames, photographs, slideshow projectors or print layouts that still follow the 4:3 standard, or when converting legacy PAL television footage. Because the maths is exact ratio arithmetic rather than an estimate, results are accurate for any consistent unit of measurement, so just make sure the width and height you compare use the same unit.
1. Known Dimension
2. Common 4:3 Presets
Select a standard resolution to populate the calculator.
Common 4:3 Resolutions
| Name | Width | Height | Diagonal | Total Pixels |
|---|
Calculation Breakdown
Ratio Verification
What Is the 4:3 Aspect Ratio?
An aspect ratio describes the proportional relationship between the width and height of a rectangular image, screen, or frame. A 4:3 aspect ratio means the width is four units and the height is three units. This produces a nearly square shape that was once the dominant standard for television and computer displays.
The ratio is also expressed as the decimal 1.333 (repeating), or written as 4/3. It is sometimes called "full frame" or "standard" to distinguish it from widescreen formats such as 16:9 or 16:10.
The Formula
The two formulas for working with the 4:3 ratio are straightforward:
- Height from width: height = width × 3 ÷ 4 (or width × 0.75)
- Width from height: width = height × 4 ÷ 3 (or height × 1.3333)
- Diagonal: diagonal = √(width² + height²) using the Pythagorean theorem
For example, if you know the width is 1,024 pixels, the height is 1,024 x 0.75 = 768 pixels. The diagonal is √(1,024² + 768²) = √(1,048,576 + 589,824) = √1,638,400 = 1,280 pixels.
Worked Example
Using the default inputs (width = 1,024 px):
- Height = 1,024 × 3/4 = 768 px
- Diagonal = √(1,024² + 768²) = √1,638,400 = 1,280.0 px
- Total pixel area = 1,024 × 768 = 786,432 px² (786K)
These match the calculator output for 1024 x 768, the XGA standard.
Common 4:3 Resolutions and Uses
| Resolution | Name | Common Use |
|---|---|---|
| 640 x 480 | VGA | Early PC monitors, DVD menus, retro gaming |
| 800 x 600 | SVGA | Standard PC monitors (1990s to early 2000s) |
| 1024 x 768 | XGA | Laptop screens, projectors, older tablets |
| 1280 x 960 | SXGA (variant) | Higher-res 4:3 desktops and projectors |
| 1400 x 1050 | SXGA+ | High-res 4:3 laptops and monitors |
| 1600 x 1200 | UXGA | High-end CRT monitors, professional photography |
| 2048 x 1536 | QXGA | iPad Retina (original), high-res scanning |
When Is 4:3 Used Today?
While 16:9 has replaced 4:3 for most consumer televisions and monitors, 4:3 remains common in several areas:
- Photography: Micro Four Thirds (MFT) cameras use a 4:3 sensor, which is a native 4:3 ratio. Many compact cameras also default to 4:3.
- Projectors: Older business projectors and some classroom projectors output in 4:3, so slideshow presentations often use 4:3 layouts.
- Print: Standard print sizes such as 4 inches x 3 inches (or scaled equivalents) follow this ratio, making it useful in desktop publishing.
- Gaming: Some competitive gamers prefer 4:3 stretched or native resolutions on modern hardware for gameplay reasons.
- Legacy video: PAL analogue television (as used in New Zealand until the switch-off in 2013) was broadcast in 4:3. Archiving or converting this content often requires working in 4:3 dimensions.
4:3 vs 16:9
The 16:9 ratio (decimal 1.778) is wider and shorter relative to its width than 4:3 (decimal 1.333). When displaying 4:3 content on a 16:9 screen, black bars appear on the left and right sides (called "pillarboxing"). Conversely, when a 16:9 image is displayed on a 4:3 screen, black bars appear at the top and bottom ("letterboxing"). To avoid bars, some devices stretch the image, which distorts the proportions.
Related Calculators
- Essential Calculators: browse all converter and utility tools.
- Aspect Ratio Calculator: calculate any width/height ratio.
- 16:10 Aspect Ratio Calculator: WUXGA and similar widescreen formats.
- Screen Ratio Calculator: find the ratio from any screen dimensions.
- Image Ratio Calculator: resize images while keeping proportions.
- AAA Triangle Calculator: angles, Sides and Area from Three Angles.
- AAS Triangle Calculator: angle-Angle-Side Solver.
Method: Standard aspect ratio arithmetic: height = width x 3/4; width = height x 4/3; diagonal = √(width² + height²) via the Pythagorean theorem. No rounding is applied until display.
This calculator applies the exact 4:3 ratio formula. Results are correct for any unit of measurement (pixels, centimetres, inches, etc.) as long as you use the same unit for both dimensions. Diagonal results assume a flat rectangular geometry.