Image DPI Checker

What is DPI?

DPI stands for "dots per inch." Originally, it describes how many individual ink dots a printer can place within one linear inch of paper. A 600 DPI laser printer physically deposits 600 dots per inch along both axes — that's the mechanical resolution of the printer, not the image being printed.

In everyday use, "DPI" has been repurposed as a loose synonym for image resolution. You'll see photographers, printers, and web developers say things like "I need a 300 DPI image", when what they really mean is "the image should contain enough pixels to print at 300 pixels per inch at the intended physical size." That's a subtle but important distinction — and it's why this tool separates embedded DPI metadata from calculated print dimensions.

What is PPI?

PPI stands for "pixels per inch." It's the technically correct term for digital image resolution: how many pixels are mapped to each inch of physical space when the image is printed or displayed. A digital image doesn't have an inherent PPI — it has pixel dimensions. PPI only becomes meaningful when you decide on a physical output size.

For example, a 3000 × 2000 pixel image:

• At 300 PPI → 10 × 6.67 inches.
• At 150 PPI → 20 × 13.33 inches.
• At 72 PPI → 41.67 × 27.78 inches.

Same pixels, different physical dimensions. The pixel data never changed.

What is image resolution?

"Image resolution" is an overloaded term. It can mean:

• Pixel dimensions — the number of pixels in width and height (e.g. 6000 × 4000). This is a real, measurable property of the file.
• Pixel density — how those pixels map to physical space when printed (PPI).
• Metadata resolution — the DPI/PPI value embedded in EXIF/JFIF/pHYs chunks, indicating the intended density of the original capture or export.

This tool reports all three separately so you never confuse one with another.

How to check image DPI

Upload your image above. The tool:

1. Reads pixel dimensions directly from the browser's native image decoder (works for every format the browser supports).
2. Parses embedded resolution metadata: EXIF/JFIF for JPEG and TIFF, pHYs for PNG.
3. Reports horizontal and vertical PPI separately if they differ.
4. Calculates physical print dimensions from the embedded PPI when available.
5. Provides a print size calculator for images with no metadata, so you can compute hypothetical dimensions at any target PPI.

Everything happens locally in your browser — no upload, no external metadata API.

How image DPI metadata works

Different image formats store resolution metadata in different ways:

• JPEG — two mechanisms. The older JFIF marker stores a density unit (no units, DPI, or DPCM), an X density, and a Y density. The EXIF block stores XResolution, YResolution, and ResolutionUnit. Modern cameras write EXIF; older software writes JFIF.
• PNG — the pHYs chunk stores pixels per unit, where the unit is either "unknown" or "meters." PPI = pixels-per-meter × 0.0254.
• TIFF — resolution is a first-class field in the baseline IFD, with the same EXIF structure.
• WebP, GIF, BMP — mostly lack resolution metadata. Dimensions are readable; DPI typically isn't present.

The tool parses the format that matches your file, and reports the exact source ("EXIF", "JFIF", "PNG pHYs") so you know where the number came from.

DPI vs PPI — the terminology

Strictly speaking:

• DPI describes printer dots — the physical ink placement density.
• PPI describes image pixels — how many image pixels map to an inch of output.

In practice, the two are often conflated. A file "at 300 DPI" and a file "at 300 PPI" are the same thing in everyday conversation. Where precision matters — like in a print-production spec — the distinction is worth preserving. This tool uses "DPI / PPI" in the UI for familiarity, but the underlying calculation is always pixels ÷ PPI.

DPI vs pixel dimensions

These are completely independent:

• Pixel dimensions are the actual data — how many pixels exist.
• DPI metadata is a hint — a suggestion about what physical density the creator intended.

Two images can have identical pixel data and different DPI metadata. A 3000 × 2000 image with 72 PPI and the same 3000 × 2000 image with 300 PPI contain exactly the same pixels. Changing the metadata value doesn't change the image; it changes the implied physical size.

DPI vs image quality

An image's quality is determined by the pixels it contains — their count, sharpness, and how well they were captured. DPI metadata is not quality. A sharp 12-megapixel photo at "72 DPI" metadata is identical in quality to the same file re-saved with "300 DPI" metadata. Conversely, an upscaled 1-megapixel image with "300 DPI" metadata is still a 1-megapixel image.

What does affect perceived quality is whether the available pixels are enough for the intended output. A 1200 × 800 image printed at 8 × 6 inches yields 150 PPI on paper — usually acceptable for a close-viewed photo but visibly soft compared to a 2400 × 1600 version printed at the same size (300 PPI).

How to calculate print size

The formula is simple:

width_inches  = pixel_width  / PPI
height_inches = pixel_height / PPI

Example — a 6000 × 4000 image at 300 PPI:

6000 / 300 = 20 inches
4000 / 300 = 13.33 inches

Convert to other units with:

• 1 inch = 2.54 cm = 25.4 mm

The Print Size Calculator above does this interactively. If the embedded metadata provides a PPI, the tool uses it. If not, you choose a target PPI and the calculator shows what the dimensions would be.

How to calculate pixels from a print size

The inverse calculation:

required_pixel_width  = print_width_inches  × PPI
required_pixel_height = print_height_inches × PPI

Example — you want an 8 × 10 inch print at 300 PPI:

8  × 300 = 2400 pixels wide
10 × 300 = 3000 pixels tall

If your source image is smaller than that, the print workflow will either upscale (introducing softness) or accept a lower effective PPI. The Required Pixels calculator above lets you plan this before you commit to a print size.

What is 300 DPI?

300 PPI is a widely used industry heuristic for "high-quality print." It's a comfortable target for close-viewed prints — books, magazines, brochures, business cards, fine-art prints — because at typical reading distance, the human eye can't resolve finer detail than roughly 300 PPI. It's not a magic number, and it isn't universal: large-format prints (posters, banners, billboards) often look fine at 100–150 PPI because they're viewed from a distance.

Is 300 DPI always required?

No. Print resolution requirements depend on:

• Viewing distance — a billboard at 30 PPI looks sharp from across the street.
• Printing process — offset printing, digital toner, inkjet, and dye-sublimation each have different optimal PPI ranges.
• Paper and ink — coated stock holds finer detail than newsprint.
• Content — fine text needs higher PPI than a soft-focus portrait.
• Intended use — a photo book and a trade-show banner have different tolerances.

300 PPI is a safe default for small prints. It is not a universal requirement.

What is 72 DPI and 96 DPI?

72 PPI is a legacy default that originated with early Macintosh displays — one pixel was one point, and one point was 1/72 inch. 96 PPI is the equivalent for Windows, where the historical display standard was 96 pixels per inch. Both numbers persisted as default resolution metadata long after they stopped being meaningful, which is why you'll often find photos with "72 DPI" metadata that were never intended for screen-only use.

Neither is a print requirement. 72 PPI and 96 PPI are display conventions, not printing standards.

Why DPI metadata can be missing

Many images simply don't carry resolution metadata:

• Web screenshots and exports often omit it.
• Some PNG encoders don't write the pHYs chunk by default.
• GIF and BMP have no standard place for it.
• WebP usually doesn't carry it.
• Some tools strip metadata for privacy.

When the metadata is missing, this tool reports "DPI/PPI: Not available" — it never invents 72 or 96. It also provides the calculator so you can still determine hypothetical print dimensions for any target PPI.

Changing DPI vs resizing an image

These two operations are often confused:

• Changing DPI metadata rewrites a number in the file header. Pixel data stays identical. The implied physical size changes.
• Resampling actually changes the number of pixels — either upsampling (interpolating new pixels) or downsampling (discarding pixels).

This tool does not modify your image in either way. It only reads and reports.

Image resolution for web

For the web, DPI metadata is irrelevant. Browsers display images at their pixel dimensions, mapped to CSS pixels. What matters is choosing the right pixel dimensions for each display context, and using responsive images (srcset, sizes) so high-DPI displays get sharper assets without every user paying the bandwidth cost.

Image resolution for print

For print, pixel dimensions and target physical size together determine PPI. A common workflow:

1. Choose the printed size (e.g. 8 × 10 inches).
2. Choose the target PPI (e.g. 300 for close-viewed, 150 for large format).
3. Calculate required pixels (2400 × 3000 or 1200 × 1500).
4. Export the image at exactly those dimensions, or crop to fit.

Use the Required Pixels calculator above to plan this before export.

Common print size examples

• 4 × 6 in at 300 PPI → 1200 × 1800 px
• 5 × 7 in at 300 PPI → 1500 × 2100 px
• 8 × 10 in at 300 PPI → 2400 × 3000 px
• A4 (210 × 297 mm) at 300 PPI → ≈2480 × 3508 px
• US Letter (8.5 × 11 in) at 300 PPI → 2550 × 3300 px
• A3 (297 × 420 mm) at 300 PPI → ≈3508 × 4961 px

These are calculations from physical size × PPI, not universal requirements. Larger prints viewed from further away can often use lower PPI.

Common DPI mistakes

• Assuming every image is 72 DPI. Many are, but not all — some have no metadata at all.
• Thinking "changing DPI" adds detail. It doesn't. Only resampling or additional capture can add detail.
• Confusing PPI with pixel dimensions. They describe different things.
• Exporting at "300 DPI" with pixel dimensions too small. The file will print at 300 PPI metadata but look soft because there aren't enough pixels.
• Trusting file metadata over pixel count. The pixels are the truth; the metadata is a hint.

How developers use image DPI checking

• Validate uploads — reject product images that don't meet minimum resolution for their intended display size.
• Prepare print-ready assets — verify pixel dimensions before sending files to a print shop.
• Debug export pipelines — check whether your image processor is stripping or preserving DPI metadata.
• Audit asset libraries — find images that lack resolution metadata or contain inconsistent values.
• Automate QA — extract the JSON report and assert minimum dimensions in CI.
• Preserve privacy — verify that exported files don't retain GPS or EXIF after your pipeline runs.

Privacy and processing

Everything on this page runs locally in your browser. Your image is read from disk into memory, its metadata is parsed with a JavaScript EXIF/pHYs parser, and its dimensions are read from the browser's native image decoder. Nothing is uploaded, nothing is logged, and no analytics event contains your filename, image data, EXIF, GPS, or resolution values. The page works offline once loaded.

Related developer tools

• HEIC to JPG Converter — convert HEIC/HEIF images so the browser can preview them here.
• Hash Generator & Checksum Tool — compute SHA-256 or MD5 for the file itself.
• Base64 Encoder & Decoder — embed images in API payloads or data URLs.
• PDF Page Size Checker — inspect page dimensions in print-ready PDFs.
• Universal Data Transformer — convert metadata reports into JSON, CSV, or SQL.
• JSON Diff — compare metadata reports across versions.
• UUID Generator & Validator — generate unique IDs for batch jobs.
• JSON vs XML comparison guide — background on data formats.

Frequently asked questions

What is DPI?

Dots per inch — the density at which a printer places ink dots. In casual use it's often used to mean image resolution, though PPI is more accurate for digital images.

What is PPI?

Pixels per inch — how many image pixels map to each inch of physical output when printed or displayed.

What is the difference between DPI and PPI?

DPI describes printer dots; PPI describes image pixels. The two are often used interchangeably in everyday speech, but they are technically distinct.

How do I check the DPI of an image?

Upload the image above. The tool reads embedded resolution metadata and reports it, or says "Not available" if the file doesn't carry it.

How do I check image resolution?

Pixel dimensions come from the browser's image decoder; DPI/PPI metadata comes from parsing EXIF, JFIF, or PNG pHYs chunks. Both are shown above.

What is 300 DPI?

A common industry target for high-quality print. It's a comfortable density for close-viewed prints, but it's a heuristic, not a universal requirement.

Is 300 DPI required for printing?

No. Requirements depend on viewing distance, printing process, paper, and content. Large-format prints often look fine at 100–150 PPI.

What is 72 DPI?

A historical screen-display default (one pixel per point, 72 points per inch). It has no special meaning for print.

What happens if an image has no DPI metadata?

The image still has pixel dimensions. The tool shows "DPI/PPI: Not available" and provides a calculator so you can determine print size for any target PPI you choose.

Can I change DPI without changing image quality?

Changing the metadata field alone doesn't affect the pixels. It changes only the implied physical size. Real quality changes require resampling.

Does changing DPI increase resolution?

No. Changing the DPI metadata doesn't add pixels. Only resampling (upscaling or downsampling) changes pixel count.

What is the difference between DPI and pixel dimensions?

Pixel dimensions describe how many pixels exist in the file. DPI describes how many of those pixels map to each physical inch when printed. They're independent properties.

How do I calculate print size from pixels?

Divide pixel dimensions by the target PPI: width_inches = pixel_width / PPI. The Print Size Calculator above does this for you.

How many pixels do I need for an 8 × 10 print?

At 300 PPI: 2400 × 3000 px. At 150 PPI: 1200 × 1500 px. Use the Required Pixels calculator above to plan for any size and PPI.

How many pixels do I need for A4 at 300 DPI?

A4 is 210 × 297 mm ≈ 8.27 × 11.69 in. At 300 PPI that's about 2480 × 3508 px.

Can I check JPEG DPI?

Yes. The tool parses JFIF and EXIF resolution fields in JPEG files.

Can I check PNG DPI?

Yes, if the PNG contains a pHYs chunk. Many PNGs don't, in which case the tool reports "Not available."

Does this tool upload my image?

No. Everything runs locally in your browser. Your image is never sent anywhere.

Does DPI determine image quality?

No. Quality is determined by the pixels the file contains. DPI metadata is a hint about intended physical density, not a quality measure.

What does 300 × 300 DPI mean?

Horizontal resolution is 300 PPI and vertical resolution is 300 PPI. For most images the two are equal; when they differ, this tool reports each separately.

Why are horizontal and vertical DPI different?

Some capture or export pipelines write different values, usually due to a bug or a deliberate non-square scaling. When this happens, physical dimensions are computed independently per axis.