For a 4:3 frame, multiply the width by 0.75 to get the height, or the height by 4/3 to get the width. A 1024-pixel-wide image is 768 pixels tall. From a diagonal, the width is 80% of it and the height 60%, so a 20-inch 4:3 monitor measures 16 × 12 inches.
The 4:3 ratio is the native shape of most Micro Four Thirds and compact camera sensors, many phone photos, older TVs and projectors, and print sizes such as 6 × 4.5. When you crop a photo, plan a slideshow or size a canvas, you often know one side and need the other. Pick which measurement you know — width, height or diagonal — and type it in. The tool returns both sides, the diagonal and the area in the same unit you entered, with the working shown. It does not know pixels from inches, so keep units consistent, and it assumes square pixels; anamorphic video with non-square pixels needs its pixel aspect ratio applied separately.
Select Width, Height or Diagonal in the selector at the top.
Type the measurement in any unit — pixels, inches, millimetres.
The headline shows width × height; below it are the diagonal and the area, plus the working.
Result 4:3 width × height: 1024 × 768
Width: 1,024
Height: 768
Diagonal: 1,280
Area (square units): 786,432
1024 × 3 ÷ 4 gives 768, the classic XGA projector and monitor resolution.
Result 4:3 width × height: 640 × 480
Width: 640
Height: 480
Diagonal: 800
Area (square units): 307,200
480 × 4 ÷ 3 gives 640, the VGA frame; its diagonal is 800 px.
Result 4:3 width × height: 16 × 12
Width: 16
Height: 12
Diagonal: 20
Area (square units): 192
A 20-inch diagonal splits 4:5 and 3:5, so the visible panel is 16 by 12 inches.
H = W × 3 ÷ 4; W = H × 4 ÷ 3; W = D × 4 ÷ 5, H = D × 3 ÷ 5
WHDA 4:3 frame is four equal parts wide and three tall. The width and height form the legs of a right triangle whose diagonal, by Pythagoras, is √(4² + 3²) = 5 parts. So one part is the diagonal ÷ 5, and the sides are 4 and 3 of those parts. Results are kept to two decimals; for pixel sizes, a width that is a multiple of 4 gives a whole-number height.
Common ones are 640 × 480 (VGA), 800 × 600 (SVGA), 1024 × 768 (XGA), 1600 × 1200 (UXGA) and 2048 × 1536 (QXGA). Each width is a multiple of 4, so the height comes out whole.
The sensor itself is 17.3 × 13 mm, almost exactly 4:3. Shooting in that ratio uses the whole sensor; choosing 3:2 or 16:9 in the camera crops off the top and bottom, so you record fewer pixels.
Take 80% of the diagonal for the width and 60% for the height. A 15-inch 4:3 display is 12 × 9 inches, and a 100-inch 4:3 projection screen is 80 × 60 inches.
Keep the height and set the width to height × 4/3. A 6000 × 4000 image becomes 5333 × 4000 after cropping about 667 pixels off the sides, roughly 11% of the width.
Not quite. 8 × 6 inches and 12 × 9 inches are exact 4:3 prints, but 8 × 10 is 5:4 and A4 is about 1.41:1, so a 4:3 photo on those papers needs cropping or a border.
Yes. Four divided by three is 1.333…, which film and broadcast people write as 1.33:1 or call the Academy-era television ratio. It is narrower than 16:9 (1.78:1).
Using this tool in an assignment, article or report? Copy a citation, or a link for your website.
Tools Directory Editorial Team. (2026, October 9). 4:3 Calculator. Tools Directory. Retrieved October 27, 2026, from https://tools.milunir.com/photography/photography-planning/4-3-calculator/
Tools Directory Editorial Team. “4:3 Calculator.” Tools Directory, 9 Oct. 2026, https://tools.milunir.com/photography/photography-planning/4-3-calculator/. Accessed 27 Oct. 2026.
Tools Directory Editorial Team. “4:3 Calculator.” Tools Directory. Last modified October 9, 2026. Accessed October 27, 2026. https://tools.milunir.com/photography/photography-planning/4-3-calculator/.
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