Photo and Print Aspect Ratios: 3:2, 4:3, and 4:5

Photo and Print Aspect Ratios: 3:2, 4:3, and 4:5

Every camera sensor has an aspect ratio, and every print size does too. The mismatch between them is the most common source of unexpected cropping in photography. A full-frame DSLR sensor is 3:2, which matches a 6×4-inch (4R) print exactly. A Micro Four Thirds sensor is 4:3, which matches a 6×4.5-inch print, not the standard 4R. Using a 3:2 camera file to order a 5×7-inch (7:5 ratio) print requires cropping roughly 11% of the long edge.

Understanding which camera sensor ratio matches which print format avoids cropping surprises. This guide covers the three main sensor ratios (3:2, 4:3, and 4:5), the standard print sizes they match, and the crop calculations for converting between formats. Use the CapyToolkit aspect ratio calculator to find the exact number of pixels to trim from any side before submitting your photos to a print lab.

Camera sensor ratios

Full-frame and APS-C sensors in cameras from Canon, Nikon, Sony, and Fujifilm capture natively at 3:2. A 24-megapixel full-frame sensor captures 6000×4000 pixels exactly at 3:2. Micro Four Thirds sensors from Panasonic and OM System capture at 4:3; a 20-megapixel MFT sensor produces approximately 5184×3888 pixels. Smartphone cameras use various ratios, many default to 4:3 capture but offer 16:9, 1:1, and full-sensor modes in settings. Consequently, knowing your sensor ratio is the starting point for any print-sizing workflow, and matching it to the intended print format before shooting prevents unwanted subject crops when the print lab processes your final order.

Standard print sizes and their ratios

Print labs offer sizes that correspond to specific ratios: 4×6 inches (3:2), 5×7 inches (7:5), 8×10 inches (5:4), and 11×14 inches (near 4:3).¹ A 3:2 camera file fits a 4×6 print with no cropping. The same file needs a 14% crop on the long dimension for a 5×7 print. For an 8×10 print, the crop removes 20% of the long dimension from a 3:2 file.

Square and non-standard prints

Square prints (1:1) require the most aggressive crop: from a 6000×4000 file, the largest square is 4000×4000, removing one third of the total image width. Print labs apply automatic center crops if you do not specify a crop zone, so always preview the crop in your editing software before submitting the file to avoid cutting off key subject matter near the frame edges.

A reliable habit is to compose with the final print ratio in mind rather than cropping after the fact. When you must crop, set the crop box yourself in your editor and place the subject within the central area the lab would otherwise choose automatically. The CapyToolkit calculator shows the exact pixel dimensions of any square or non-standard crop, so you can confirm the file still has enough resolution for a sharp 300 DPI print before sending it to the lab.

Choosing the right export ratio for each format

Before submitting to a print lab, export a cropped file at exactly the print ratio. For a 4×6 (3:2) print from a 6000×4000 source, no crop is needed. Export at full size or at the lab's recommended resolution (typically 1800×1200 pixels for 300 DPI on a 4×6 print). For a 5×7 (7:5) print, calculate the crop: at 4000 pixels tall and 7:5 ratio, the width is 4000 × 7/5 = 5600 pixels. Crop the source from 6000 to 5600 wide, removing 400 pixels (200 per side). The lab receives a 5600×4000 file that maps exactly to 7:5 at 300 DPI.

Matching camera sensor ratios to print sizes without cropping

A 3:2 full-frame sensor (Canon EOS R5, Sony A7 IV, Nikon Z8) captures 8192×5464 pixels at 45 megapixels.² This ratio fits a 4×6-inch print at 300 DPI with zero cropping (3600×2400 pixels needed, source has 8192×5464). For a 12×8-inch print, the same sensor produces a 3600×2400 pixel crop that maps exactly to the 2:3 ratio of the 8×12 print.

Micro Four Thirds sensor matching

A 4:3 Micro Four Thirds sensor (Panasonic GH6 at 5776×4336) fits a 6×4.5-inch print natively³ and an 8×6-inch print with minimal cropping. The mismatch appears at 5×7 inches: a 4:3 source at 4000 pixels tall produces a 5600-pixel-wide crop at 7:5, but the sensor is only 5184 pixels wide, so you must upscale or accept a lower DPI. Understanding which print sizes match your sensor ratio prevents surprises at the lab. The CapyToolkit calculator shows the exact crop dimensions for any sensor-to-print combination.

DPI requirements and viewing distance

The standard 300 DPI for photo prints assumes a viewing distance of 10 to 12 inches, which matches how people hold 4×6 and 5×7 prints. For larger prints viewed from farther away, lower DPI is acceptable. A 24×36-inch poster viewed at 3 feet looks sharp at 150 DPI (3600×5400 pixels). A 40×60-inch canvas print viewed at 6 feet looks acceptable at 100 DPI (4000×6000 pixels). This means a 24-megapixel sensor (6000×4000) can produce a 40×60 canvas at 100 DPI without upscaling.

When to upscale versus when to crop

Mpix and Shutterfly both accept files at 150 DPI for large prints and apply mild upscaling in their print pipeline. Before sending a file to the print lab, match your sensor ratio to the target print size so you crop the correct number of pixels from each edge. For the sharpest results, deliver at 300 DPI for prints up to 12×18 inches, 200 DPI for prints up to 20×30 inches, and 150 DPI for anything larger. The CapyToolkit calculator does not compute DPI, but knowing the pixel dimensions it shows for any crop tells you whether your file meets these thresholds.

When to use this

Use this when ordering prints, designing photo books, or planning camera crops for specific print formats. Calculate the correct pixel dimensions before shooting when you know the final print size. This determines the safe zone for your composition.

Examples