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File Resolution & Quality Requirements: DPI, Pixels & Print Quality

Pro Lab file resolution guide — 300 DPI recommended, 150 DPI minimum, exact pixel sizes for every print size from 4x6" to 24x36", how to check resolution, and how to fix low-res photos.

For sharp, professional prints, Pro Lab recommends a minimum of 300 DPI at print size, with 150 DPI as the practical minimum. Resolution is the single biggest factor in print sharpness — this guide explains what DPI is, how to check your files, and how to avoid blurry or pixelated prints.

What is DPI?

DPI stands for dots per inch — a measure of how much detail an image has at its final print size. Higher DPI means more pixels packed into each inch of the print, resulting in sharper, more detailed images.

  • 300 DPI — professional print quality (recommended)
  • 150 DPI — acceptable for casual prints (minimum)
  • Below 150 DPI — may appear soft or pixelated

How resolution and print size relate

The larger you print, the more pixels you need. A photo that looks sharp at 4x6" may look soft at 20x30".

Quick reference: minimum pixel dimensions per print size

Print Size
Minimum (150 DPI)
Recommended (300 DPI)
4x6"
600 × 900 px
1200 × 1800 px
5x7"
750 × 1050 px
1500 × 2100 px
8x10"
1200 × 1500 px
2400 × 3000 px
8x12"
1200 × 1800 px
2400 × 3600 px
12x18"
1800 × 2700 px
3600 × 5400 px
16x24"
2400 × 3600 px
4800 × 7200 px
20x30"
3000 × 4500 px
6000 × 9000 px
24x36"
3600 × 5400 px
7200 × 10800 px

How to check your photo's resolution

On a computer (Windows)

Right-click the file → PropertiesDetails tab → see Dimensions (e.g. 4000 × 3000)

On a Mac

Right-click the file → Get Info → see Dimensions under "More Info"

On a phone (iPhone or Android)

Open the photo → swipe up or tap "i" info icon → see image dimensions

Inside the Pro Lab editor

The editor automatically flags low-resolution photos with yellow or red warnings. Heed these — they're your reliable guide.

What happens if my resolution is too low?

Low-resolution photos at large print sizes appear:

  • Soft and blurry — detail looks smudged
  • Pixelated — you can see individual pixels as blocks
  • Jagged edges — lines and text look stepped instead of smooth

No printing process can fully restore detail that wasn't in the original file. Heed the warnings.

Common causes of low-resolution photos

  1. WhatsApp / social media compression — the #1 cause. Always use originals.
  1. Screenshots — often only the size of the screen (e.g. 1920 × 1080)
  1. Web downloads — web images are typically optimised for screen, not print
  1. Digital zoom — phone or camera zoom that crops, reducing usable pixels
  1. Heavy cropping — cropping a small section of a photo leaves few pixels for printing
  1. Old photos from low-res cameras — early digital cameras shot at 2–3 megapixels (too low for large prints)

How to fix low-resolution photos

Best option: re-upload the original

If you used a compressed copy, go back to your camera or phone gallery and upload the full-resolution original.

Choose a smaller print size

If the photo is genuinely low-resolution, print at a smaller size where it still looks sharp. A 1200 × 800 photo can print beautifully at 4x6" but not at 16x24".

Apply Pro Lab AI enhancement

Our AI enhancement can improve clarity and sharpness on borderline photos — it's not magic, but it visibly helps.

Use a different, sharper photo

If the source photo is irreparably low-resolution, choose a different photo of the same moment if available.

Have it professionally upscaled (last resort)

For irreplaceable family or heritage photos that are too low-resolution, contact support@prolab.in — we can advise on professional upscaling for an additional fee.

File format recommendations

We also support the following formats at the highest quality:

  • JPEG — the standard choice for photos. Use the highest quality setting.
  • PNG — best for graphics, logos, and screenshots; larger file sizes
  • RAW — not directly supported; convert to JPEG with high quality first

Colour space (advanced)

For professional photographers and designers:

  • sRGB — recommended for web and consumer prints (Pro Lab default)
  • Adobe RGB — wider colour gamut; supported for giclée fine art prints
  • CMYK — not used by Pro Lab; convert to RGB before uploading

If you're unsure, leave your photos in sRGB — it's the safest and most consistent choice.

Quick checklist before ordering

  • ✅ Photos uploaded are originals, not compressed copies
  • ✅ No yellow/red quality warnings in the editor
  • ✅ Photo dimensions match the print size (use the table above)
  • ✅ Cropping doesn't cut faces or important details
  • ✅ Colour space is sRGB unless specifically using Adobe RGB for giclée
  • ✅ Preview at full size and zoom in to check sharpness

Still unsure?

If you're not sure whether your file is good enough to print at the size you want, contact support@prolab.in with your order details and we can review the files for you before you place the order.

For more on print quality and the difference between silver halide and giclée, see our Photo Prints and Giclée Fine Art Prints articles.

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