Photo Size to Pixels Converter

The Relationship Between Photo Size and Pixels

A 4×6 inch photo requires 1200×1800 pixels for clear printing at 300 DPI. Pixels are the smallest color blocks in a digital image, and DPI (dots per inch) determines the density of these blocks when printed. The formula is simple: Pixels = Size in Inches × DPI. Tell the calculator the physical size of the photo paper and set your desired DPI, and it will calculate how many pixels your image needs. This tool features dozens of common sizes like 1-inch, 2-inch, 5-inch, 6-inch, and A4. It automatically converts millimeters and centimeters to inches. Just select the size, enter the DPI, and the pixel width and height will instantly appear on the right.

How to Use This Tool

1. Select a size: Open the page, and you will see a "Size" dropdown menu. Click it to select options like "6-inch (4×6 inches)" or "2-inch (35×49 mm)".
2. Enter the DPI: Input your target value in the DPI field below, such as 300 for printing or 72 for web display.
3. View the results: After selecting the size and entering the DPI, the "Width" and "Height" cards on the right will immediately display the corresponding pixel dimensions. No need to click any buttons.
4. Compare effects: You can also change the DPI value to see how the pixel results change. For example, changing it from 300 to 150 will cut the pixel values in half.
5. Copy and use: Copy the pixel values into your design software, photo printing order, or code to complete the conversion from physical size to digital pixels.

Complete Example: 4×6 Inch Photo Printing

You plan to print a standard 4×6 inch family photo, and the print shop requires "300 DPI, minimum 1200×1800 pixels." How do you confirm this?

Select "6-inch (4×6 inches)" from the calculator's size dropdown menu. Enter 300 in the DPI input box. The calculator displays: Width 1200 px, Height 1800 px. This result comes exactly from 4 inches × 300 and 6 inches × 300: 4″ × 300 = 1200 px, 6″ × 300 = 1800 px. This means your digital photo must be at least 1200×1800 pixels for the printed 4×6 photo to be sharp and clear. If your original phone photo is only 800×1200 pixels, the printed image will appear pixelated or blurry. In this case, you either have to accept lower clarity or print at a smaller size.

More Examples / Scenario Comparisons

2-inch ID photo: Applying for a passport requires a 2-inch bareheaded photo, and many photo studios ask for a digital version at 413×579 pixels. Where does this come from? Select "2-inch (35×49 mm)" in the tool and set the DPI to 300. 35 mm ÷ 25.4 ≈ 1.378 inches, and 49 mm ÷ 25.4 ≈ 1.929 inches. Multiplying these by 300 gives ≈ 413 px and 579 px, respectively. Crop your photo to these exact pixel dimensions before submitting, and the size will be perfectly accurate.

The same photo on a webpage: For the same 4×6 inch image, if it's just for a personal blog, you don't need 300 DPI. Keep the size at "6-inch (4×6 inches)" and change the DPI to 72. The calculator outputs 288×432 px. This pixel size looks clear on a screen, and the file size is much smaller, allowing for faster loading.

Comparing the two examples: For the same physical size, dropping the DPI from 300 to 72 reduces the total required pixels from 2.16 million to about 120,000—a difference of an order of magnitude. Choosing the right DPI directly determines whether your image file is "just right" or "wasted space."

How to Interpret the Results / What Pixel Values Mean

The width and height pixels provided by the calculator represent the "digital size" your image needs to achieve.

• If you plan to print, and your actual image pixels are ≥ the calculated result, the printed photo will be sharp. If it's below 80%, the naked eye will notice blurriness or pixelation.
• If it's just for screen display, there's no need to obsess over 300 DPI. The pixels corresponding to 72–96 DPI are plenty. Screens cannot display the excess detail anyway; it will only make the file unnecessarily large.
• When the calculated result exceeds 5000×7000 pixels (e.g., an A3 brochure at 300 DPI), it means your image file will be massive. Be mindful of your computer's RAM and software processing capabilities.

A simple rule of thumb: For printing, aim for "no less than"; for screens, aim for "just enough."

Typical Use Cases

ID photo creation: When students or professionals apply for various IDs, they are often asked for a "1-inch white background 295×413 pixels" or "2-inch blue background 413×579 pixels" photo. By selecting the size and setting the DPI in this calculator, you'll know exactly what pixel dimensions to crop your photo to, avoiding the hassle of retaking it.

Online photo printing orders: When uploading photos to a printing website, the system usually prompts "Recommended pixels XXXX×XXXX." If you're unsure whether your original photo is large enough, you can use the calculator to match your chosen print size and DPI. Confirm the dimensions before uploading to reduce rejected orders.

Poster and brochure layout: When designers create a new canvas in Photoshop or Illustrator, they need to calculate the pixel width and height based on the final print size and DPI. For instance, for a single A4 brochure page (210×297 mm) at 300 DPI, the tool instantly provides 2480×3508 px, which can be used directly as the dimensions for the new file.

Common Mistakes / Pitfalls to Avoid

1. Assuming screen clarity equals print clarity: Images downloaded from social media look sharp on a phone but typically only have the small pixel dimensions associated with 72 DPI. If you send them directly to print a 4×6 photo, they will likely turn out blurry. Always verify the pixels with this tool before printing.
2. Judging only by total pixels, ignoring aspect