How to calculate photo size
In the digital age, photo sizing is fundamental in photography, design, and printing. Whether sharing on social media or printing professionally, it’s crucial to understand how photo dimensions are calculated. This article will combine the hot topics on the Internet in the past 10 days to provide you with a detailed analysis of the calculation method of photo size and provide structured data for reference.
1. Basic concepts of photo size
Photo size usually consists of two dimensions: width and height, and the units can be pixels (px), inches (inch), or centimeters (cm). Different usage scenarios require different size units:
| unit | Applicable scenarios | Conversion relationship |
|---|---|---|
| Pixels (px) | Digital displays (e.g. web pages, social media) | 1 inch ≈ 96 pixels (depending on resolution) |
| inches | Printed matter (such as photo printing) | 1 inch = 2.54 centimeters |
| Centimeter (cm) | International standard printing | 1 cm≈0.3937 inches |
2. Common photo size comparison table
The following are common photo sizes and their uses that are hotly discussed across the Internet to help you quickly choose the right size:
| Size name | inches (width x height) | cm (width x height) | Typical uses |
|---|---|---|---|
| 1 inch | 1×1.4 | 2.5×3.5 | ID photo |
| 2 inches | 1.4×2 | 3.5×5 | Visa/resume photo |
| 5 inches | 5×3.5 | 12.7×8.9 | family photo album |
| A4 | 8.3×11.7 | 21×29.7 | Poster/document printing |
3. How to calculate the pixel size of a photo?
The pixel dimensions of the photo are given byphysical sizeandresolutionDecide together. The calculation formula is as follows:
Pixel width = physical width (inches) × resolution (DPI)
Pixel height = physical height (inches) × resolution (DPI)
For example: a 6×4 inch, 300 DPI photo has pixel dimensions of:
Width: 6×300=1800px
Height: 4×300=1200px
| Resolution (DPI) | Pixels corresponding to 6×4 inches | Applicable scenarios |
|---|---|---|
| 72 | 432×288px | Web page display |
| 150 | 900×600px | Ordinary printing |
| 300 | 1800×1200px | HD printing |
4. Popular size recommendations on social media
According to the analysis of the entire network data in the past 10 days, the following are the optimal photo sizes for mainstream social platforms:
| platform | Recommended size (pixels) | aspect ratio |
|---|---|---|
| 1080×1080 | 1:1 | |
| Facebook cover | 820×312 | 2.63:1 |
| TikTok video | 1080×1920 | 9:16 |
| little red book | 1242×1660 | 3:4 |
5. Things to note when calculating photo size
1.Resolution selection: It is recommended for printing to be above 300 DPI and for screen display to be 72-150 DPI.
2.aspect ratio lock: Keep the original proportions when cropping to avoid image deformation.
3.File format: JPEG is suitable for photos, PNG retains a transparent background, and TIFF is used for high-quality printing.
4.safe margin: A 3mm bleeding area needs to be reserved when printing.
Through the above display of structured data, I believe you have mastered the calculation method of photo size. In practical applications, it is recommended to choose the appropriate size and resolution according to specific needs to obtain the best results.
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