What is Image DPI?
DPI stands for Dots Per Inch and measures how many individual dots or pixels fit within one inch of a printed image. A higher DPI value means more dots packed into each inch, which produces a finer, sharper printed result. At 72 DPI, one inch of print contains 72 pixels. At 300 DPI, one inch contains 300 pixels — producing a much more detailed print.
DPI is primarily a printing concept. Digital screens display images using pixels, not dots, and screen resolution is measured in PPI (Pixels Per Inch). However, the terms DPI and PPI are commonly used interchangeably for digital images. For most practical purposes, what matters for digital files is the total pixel count, not the metadata DPI value embedded in the file.
When you scan a document at 300 DPI, the scanner captures 300 pixels for every inch of the physical document. Scanning an A4 document at 300 DPI produces a 2480×3508 pixel image. The DPI setting on a scanner directly determines the pixel count of the resulting image file, which is why scanner DPI matters practically.
DPI for Exam Portals — What Really Matters
Here is the most important thing to understand about DPI for Indian exam portals: most portals check pixel dimensions and file size in KB, not the DPI metadata embedded in the file. When an exam notification says "photo should be 200 DPI", it typically means the photo should have the same pixel dimensions as a 200 DPI photo of standard exam dimensions.
For SSC exams, the official notification says 200 DPI. What this translates to in practice: a 3.5×4.5 cm photo at 200 DPI requires 276×354 pixels. The portal does not read the DPI tag inside the JPG file. It checks whether the uploaded file is approximately 276×354 pixels and under the maximum file size. You can verify this by uploading a 276×354 pixel photo and the portal will accept it regardless of its embedded DPI tag.
The DPI to Pixels Calculator at the top of this page converts physical dimensions and DPI into the required pixel dimensions. Enter the size of your photo in centimetres, select the required DPI, and the calculator instantly shows the target pixel dimensions for resizing.
DPI Reference for Common Exam Sizes
The following reference table shows common exam photo sizes converted to pixel dimensions at different DPI values. Use this to understand what "200 DPI" or "300 DPI" means in pixels for your specific exam.
A standard 3.5×4.5 cm passport photo at 200 DPI requires 276×354 pixels. The same photo at 300 DPI requires 413×531 pixels. For a square 3.5×3.5 cm signature at 200 DPI: 276×276 pixels. A 2×2 inch photo (common for US-style forms) at 200 DPI: 400×400 pixels. A 2×2 inch photo at 300 DPI: 600×600 pixels.
For scanned documents, A4 paper (21×29.7 cm) at 200 DPI produces 1654×2340 pixels and at 300 DPI produces 2480×3508 pixels. These are large files — always compress after scanning to meet the portal's KB limit. Use our Compress tool for documents scanned at high resolution.
When DPI Actually Matters
While DPI metadata is mostly irrelevant for digital portal uploads, there are situations where DPI genuinely matters. Professional photo printing studios use DPI to determine print size. If you send a photo with 200 DPI to a print studio, they know to print it at the correct physical dimensions. Low DPI for large prints looks pixelated when printed on physical paper.
Photo identification printing for physical ID cards, driving licences, and passports requires minimum 300 DPI to produce sharp, clear photos. For document printing on physical paper, 300 DPI is standard for most desktop printers. For high-quality printing such as magazines or large format posters, 600 DPI or higher may be required.
Frequently Asked Questions
SSC typically says 200 DPI. This means resize to 276×354 pixels (3.5×4.5cm at 200 DPI). Use our calculator above to get exact pixels for your dimensions.
Only metadata DPI can change without pixel change. Most portals don't check metadata DPI. Pixel dimensions are what matter for portal uploads.
DPI = Dots Per Inch. Measures how many dots (pixels) fit in one inch of printed image. Higher DPI = sharper print.
300 DPI gives sharper prints. 200 DPI is standard for most exam portals and gives good quality for screen and standard printing.
Portals check pixels and KB, not DPI metadata. 96 DPI metadata won't cause rejection if pixel dimensions and file size are correct.
Formula: Width(cm) ÷ 2.54 × DPI = Width(pixels). Example: 3.5cm ÷ 2.54 × 200 = 276 pixels. Use our calculator above for instant results.
IBPS typically requires 200×230 pixels. The portal accepts this regardless of metadata DPI. Use our resize tool to set 200×230 pixels exactly.
Same pixel dimensions = effectively same file for portals. DPI metadata only affects print output size. The digital image data is identical.
300 DPI for quality print. 3.5×4.5cm at 300 DPI = 413×531 pixels. Use our calculator with 3.5×4.5 and 300 DPI to get exact dimensions.
Scan at 200-300 DPI. Higher DPI gives larger file. Compress after scanning using our Image Compress tool to meet portal KB limits.
Scan at 300 DPI for best balance of quality and file size. 600 DPI creates very large files that need heavy compression to meet portal limits.
UPSC portal checks pixels, not DPI. Calculate the required pixel dimensions using our calculator, then resize using our Image Resize tool.
PPI (Pixels Per Inch) = digital screen density. DPI (Dots Per Inch) = printing density. Often used interchangeably for digital images.
A4 at 300 DPI = 2480×3508 pixels. At 200 DPI = 1654×2340 pixels. Very large files — compress after scanning.
Canvas API sets standard metadata. For most exam portals this is irrelevant — focus on pixel dimensions and file size, not metadata DPI.