Separate pixel dimensions from paper shape
A 3000 × 2400 image has a 5:4 ratio. A 10 × 8 inch print also has a 5:4 ratio, so the complete image fits at 300 PPI. A 12 × 8 inch print has a 3:2 ratio. It is wider relative to its height, and the image cannot both fill it and preserve the complete composition without distortion.
Use fill when edge-to-edge coverage matters
For that 12 × 8 print, the 3000 pixel width gives 250 PPI. At the same density the eight-inch height uses 2000 pixels. A centered crop therefore retains 3000 × 2000 out of 3000 × 2400 pixels: 16.67% of the original pixels are removed. A centered crop removes equal amounts from opposite edges; move the crop in your editor if that would cut through a face or important text.
Use fit when the whole picture must remain
Keeping all 3000 × 2400 pixels inside a 12 × 8 inch area produces a 10 × 8 inch image at 300 PPI. With centered placement there is an inch of empty space on each side. This protects the composition but does not give edge-to-edge coverage. Check whether the print shop lets you choose fit, fill or borders rather than silently cropping.
Calculate the pixels required by your target
At 300 PPI a 12 × 8 inch print requires at least 3600 × 2400 pixels after cropping. Your 3000 × 2400 original cannot meet that fill target merely by changing its DPI tag. Upscaling can create an output with more pixels, but it estimates extra detail. Try a smaller print, accept a lower density when appropriate, or use a higher-resolution original. The planner rounds required dimensions upward to avoid falling below the chosen target.
Review orientation, bleed and the final preview
The planner can rotate the source dimensions when that retains more pixels. It estimates a centered crop only; it does not edit your image or know a shop’s bleed requirements. Export the intended file, verify its dimensions and inspect the shop’s preview. Focus, motion blur, paper and viewing distance still matter even when the pixel-density calculation passes.
Calculate print size from actual pixels
Print width in inches = pixel width ÷ target PPI; height uses the same calculation. Multiply inches by 2.54 for centimeters. A 3000 × 2400 pixel file gives 10 × 8 inches at 300 PPI, 12.5 × 10 inches at 240 PPI, or 20 × 16 inches at 150 PPI. Changing only the stored DPI/PPI tag does not add pixels. These sizes assume no cropping or resampling; focus, compression and viewing distance also affect the result.