Photo Dimensions Calculator

What Is This Calculator For?

Photo size requirements come in different units depending on where you're submitting — passport applications in inches or cm, social media in pixels, print shops in a mix of both. This calculator converts between all of them instantly, using a DPI value to bridge pixel dimensions and physical size, plus a set of built-in presets for the sizes people look up most often. It's a pure math tool — no image is uploaded or processed here, just the conversion itself.

How to Use This Calculator

1. 1Enter a width and heightIn whichever unit you already know — pixels, inches, cm, or mm.
2. 2Set the DPIOnly matters when converting to/from a physical unit — 300 DPI is standard for print.
3. 3Read the equivalent sizesAll four units update instantly as you type.
4. 4Or start from a presetPassport photo, Instagram post, A4 paper, and more — one click fills the calculator.

Why DPI Actually Matters

1. 1The same pixel grid, printed two different sizesA 1200×1200px image at 300 DPI prints as a 4×4 inch photo. The exact same file at 150 DPI prints as an 8×8 inch photo — twice as large, but noticeably softer, since each printed inch now has half as many dots of detail.
2. 2Screens don't really "have" a DPI in the same senseA screen just displays pixels 1:1 (roughly) regardless of DPI metadata in the file — this is why DPI is largely irrelevant for anything that will only ever be viewed on a screen, and only matters once physical printing enters the picture.
3. 3Print shops and official forms specify DPI for a reasonA photo lab or a passport office cares about DPI because it guarantees the print or scan will meet a minimum sharpness standard at the required physical size — which is why document photo requirements typically state both a physical size and a DPI together.

Good to Know

• DPI (dots per inch) is what links pixels to physical size — a 300×300px image is 1×1 inch at 300 DPI, but 3×3 inches at 100 DPI.
• 300 DPI is the standard for high-quality printing; 72–96 DPI is typical for screens, though pixel dimensions matter more than DPI for anything web-only.
• Passport and ID photo requirements vary by country — always double-check the exact requirement for your specific application before submitting.
• This is a calculator only — pair it with the Image Resizer to actually resize a photo to the dimensions you calculate here, or the Passport / ID Photo Maker for document-specific presets with built-in cropping.

Frequently Asked Questions