How this calculator works
Print size depends on two things: how many pixels an image has, and how tightly those pixels are packed onto paper (dots per inch, or DPI). The same 3000×2000 pixel photo can print as a crisp 10×6.67 inch photo at 300 DPI, or a much larger but softer 30×20 inch poster at 100 DPI — same pixels, different quality trade-off.
This calculator works in either direction: tell it your image's pixel dimensions and a target DPI to find the resulting print size, or tell it the print size you want and it works out the DPI you'd actually be printing at (and therefore how sharp the result will look).
The formulas
Print size from DPI: width (in) = pixel width ÷ DPI, height (in) = pixel height ÷ DPIRequired DPI from a target size: DPI = pixel width ÷ target width (in)Inches to centimeters: cm = in × 2.54 (exact)The 300/150/100 DPI quality bands used for the verdict are common printing industry rules of thumb, not a single official standard — different print labs, papers, and viewing distances shift the exact cutoffs slightly.
Worked example: a 3000×2000 pixel photo
- At 300 DPI (photo quality): 3000 ÷ 300 = 10 inches wide, 2000 ÷ 300 = 6.67 inches tall — a standard 10×6.67 in print.
- Convert to centimeters: 10 × 2.54 = 25.4 cm wide, 6.67 × 2.54 ≈ 16.93 cm tall.
- If instead you want a 20-inch-wide print: required DPI = 3000 ÷ 20 = 150 DPI, right at the edge of 'acceptable' quality.
- Push it to a 30-inch-wide poster: required DPI = 3000 ÷ 30 = 100 DPI, right at the top of this calculator's 'marginal' band (100-149 DPI) — fine at a distance, soft up close.
Frequently asked questions
What DPI should I use for printing photos?
300 DPI is the standard target for sharp, up-close photo prints (like 4×6 prints or framed photos). Large-format prints viewed from farther away, like posters or banners, can look fine at 100-150 DPI since the viewing distance hides the lower pixel density.
Is DPI the same as PPI?
They're often used interchangeably for digital images. Technically, PPI (pixels per inch) describes the image file's resolution, and DPI (dots per inch) describes how many ink dots a printer lays down — but for sizing a print from a digital photo, the two numbers do the same job.
Why does my print look blurry even at 300 DPI?
DPI only measures pixel density, not sharpness or focus. A print at the correct DPI will still look soft if the original photo was out of focus, heavily compressed, or upscaled from a smaller image before printing.
Can I print larger than my DPI calculation suggests?
Yes — the DPI bands are guidelines, not hard limits. Prints meant to be viewed from a distance (posters, banners, billboards) routinely use far lower DPI than photo prints because the eye can't resolve as much detail from farther away.
What print size would a 4000×3000 pixel photo give at 300 DPI?
It would print at about 13.33 × 10 inches, which is roughly 33.86 × 25.4 cm. Print width and height in inches equal the pixel dimensions divided by DPI, so 4000 ÷ 300 ≈ 13.33 inches wide and 3000 ÷ 300 = 10 inches tall; multiplying each by 2.54 converts them to centimeters. Since 300 DPI is the photo-quality threshold, that size would print sharp and detailed.