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Image File Size Calculator & Converter

Drop in an image to see exactly how big it is as JPG, PNG and WebP, then download the one you want. It's a free image converter, compressor and resizer that works right in your browser, so nothing is uploaded. Fast and 100% free.

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Free Image Converter: PNG, JPG, WebP and PDF

Most image converters upload your picture to a server, and plenty of them charge, add a watermark or cap the file size. This one does the conversion inside your browser, so it's free, instant and private: no sign-up, no watermark, no limits, and your image never leaves your device.

  1. Drop your image or PDF into the converter above, click to choose one, or paste an image with Ctrl+V.
  2. Pick a size. Original keeps it as it is; the other sizes resize it, cropping from the centre if the shape changes.
  3. Find the format and quality you want in the table. Each row shows the real file size it makes.
  4. Click Download on that row.

It handles all the everyday conversions:

  • PNG to JPG: much smaller files for photos. Transparent areas turn white.
  • JPG to PNG: for editing, or uploads that only take PNG.
  • WebP to JPG or PNG: for apps and sites that don't accept WebP yet.
  • JPG or PNG to WebP: the smallest files for websites.
  • PDF to JPG or PNG: any page of a PDF, at 72, 150 or 300 DPI. Pick a page with the arrows.
  • JPG or PNG to PDF: a one-page PDF the size of your image, or on A4 or US Letter paper.
  • Compress: lower the quality to shrink a file without changing its size in pixels.
  • Resize: to 1920 × 1080, 1280 × 720, square, vertical or any size you type.

It opens PDFs and anything your browser can show: JPG, PNG, WebP, GIF, AVIF and BMP, plus HEIC photos in Safari. Safari can't save WebP, so use Chrome, Edge or Firefox for that. PDFs with a password need unlocking first.

How to Calculate an Image's File Size

Start with the uncompressed size: every pixel stores a red, green and blue value of one byte each, so

Uncompressed size (bytes) = Width × Height × 3
With transparency (bytes) = Width × Height × 4

A 1920 × 1080 image has 2,073,600 pixels, so it's 6,220,800 bytes, about 6.2 MB, before compression. JPG, PNG and WebP then shrink that, and how much depends on the picture: a photo full of detail compresses far less than a screenshot with big areas of flat colour. That's why the calculator above saves your actual image instead of guessing.

Image sizePixelsUncompressedJPG 85%, photo
1280 × 720 (720p)0.9 MP2.76 MB115 KB – 288 KB
1920 × 1080 (1080p)2.1 MP6.22 MB259 KB – 648 KB
2560 × 1440 (1440p)3.7 MP11.1 MB461 KB – 1.15 MB
3840 × 2160 (4K)8.3 MP24.9 MB1.04 MB – 2.59 MB
4000 × 3000 (12 MP)12 MP36.0 MB1.50 MB – 3.75 MB
6000 × 4000 (24 MP)24 MP72.0 MB3.00 MB – 7.50 MB

How Many MB Is a 1920×1080 Image?

Uncompressed, a 1920 × 1080 image is 6.2 MB. Saved as a file it's usually much smaller. These ranges come from saving our own test photos and screenshots at 1920 × 1080:

FormatPhotoScreenshot or graphic
JPG 85%259 KB – 648 KB104 KB – 207 KB
WebP 85%156 KB – 467 KB52 KB – 117 KB
PNG2.59 MB – 4.15 MB259 KB – 1.30 MB

The same goes for any size: a 4K image has four times the pixels of 1080p, so expect roughly four times the file size at the same quality.

JPG vs PNG vs WebP: Which Is Smallest?

  • WebP is usually the smallest. In our tests it came out 25% to 50% smaller than JPG at the same quality setting, and Google's own study found it 25–34% smaller at the same visual quality. It can keep transparency too. Most websites, browsers and apps accept it now, but some upload forms (including YouTube thumbnails) still don't.
  • JPG is the safe choice for photos. Every app and website takes it. Quality 75–85% looks almost the same as 95% at half the size or less. It can't keep transparency.
  • PNG is lossless, so it's the biggest for photos but often the best for screenshots, text, logos and anything with sharp edges or transparency. Saving a photo as PNG can make it larger than the original JPG.

To make an image smaller in MB, try these in order: lower the JPG or WebP quality to 75–85%, shrink the dimensions (a 4000 × 3000 photo resized to 1920 × 1440 is less than a quarter of the pixels), then switch to WebP if wherever you're uploading accepts it.

Image Size and DPI: How Big It Prints

DPI (dots per inch) only matters when you print. Divide the pixels by the DPI to get inches: Print width (inches) = Width in pixels ÷ DPI. 300 DPI is the usual target for sharp photo prints, and 150 DPI is fine for posters you'll see from further away. On a screen, DPI does nothing: a 1920 × 1080 image looks the same whether its file says 72 or 300.

PixelsAt 300 DPIAt 150 DPI
1280 × 7204.3 × 2.4 in8.5 × 4.8 in
1920 × 10806.4 × 3.6 in12.8 × 7.2 in
3000 × 200010 × 6.7 in20 × 13.3 in
3840 × 216012.8 × 7.2 in25.6 × 14.4 in
4000 × 300013.3 × 10 in26.7 × 20 in

YouTube Thumbnail Size and File Limit

YouTube recommends custom thumbnails at 3840 × 2160 pixels (16:9) for videos and 2160 × 3840 (9:16) for Shorts, at least 640 pixels on the short side, as a JPG or PNG. From a computer the file can be up to 50 MB, but from the YouTube app on a phone it has to be under 2 MB (YouTube Help). The limit was 2 MB everywhere until March 2026, which is why so many guides still say it.

Plenty of creators still make thumbnails at 1280 × 720, and that's fine: it's 16:9 and well over the minimum. Drop your thumbnail into the calculator, pick a 16:9 size, and it shows the best JPG or PNG that fits each limit, ready to save.

Working on video too? The video file size calculator works out how big a video will be, and the bitrate you need to fit Discord or email.

Frequently asked questions

How do I calculate the file size of an image?

Multiply the width by the height to get the number of pixels, then by 3 bytes per pixel for an uncompressed image (4 with transparency). A 1920×1080 image is 2,073,600 pixels × 3 = 6.2 MB uncompressed. Saved as JPG, PNG or WebP it's much smaller, by an amount that depends on the picture, so the quickest way to get the real number is to drop the image into the calculator above.

How many MB is a 1920×1080 image?

6.2 MB uncompressed. Saved as a JPG at 85% quality, a 1920×1080 photo is usually about 250 to 650 KB and a screenshot about 100 to 200 KB. As a PNG, a photo is about 2.6 to 4 MB and a screenshot about 0.3 to 1.3 MB.

What size is a 1920×1080 image in inches at 300 DPI?

6.4 × 3.6 inches (16.3 × 9.1 cm). Divide each side in pixels by the DPI: 1920 ÷ 300 = 6.4 and 1080 ÷ 300 = 3.6. At 150 DPI it prints at 12.8 × 7.2 inches.

How do I make an image smaller in MB?

Lower the quality, shrink the dimensions or change the format. Saving a photo as JPG at 75–85% quality usually makes it far smaller with no visible difference, halving the width and height cuts the pixels to a quarter, and WebP is usually smaller again. Drop your image into the calculator to see the real size of every option and save the one that fits.

Is this image converter free?

Yes. It's free with no sign-up, no watermark and no limit on how many images you convert. It runs in your browser, so your images are never uploaded, and the only size limit is what your device can handle.

How do I convert PNG to JPG?

Drop the PNG into the converter, pick a size (Original keeps it as it is), then click Download on a JPG row. 85% quality looks the same as the original for most images at a fraction of the size. Transparent areas turn white, since JPG can't store transparency.

How do I convert WebP to JPG or PNG?

Drop the WebP file in and click Download on a JPG or PNG row. Choose PNG for screenshots, logos or anything with transparency, and JPG for photos. To go the other way, drop in a JPG or PNG and download a WebP row.

Can I convert iPhone HEIC photos to JPG?

In Safari on an iPhone, iPad or Mac, yes: Safari can open HEIC photos, so drop one in and download it as a JPG or PNG. Chrome and most other browsers can't open HEIC files yet. Safari also can't save WebP, so those rows show as not supported there.

How do I convert a PDF to JPG?

Drop the PDF into the converter. It shows page 1 as an image; use the arrows to pick another page and choose 72, 150 or 300 DPI (300 keeps small text sharp), then click Download on a JPG or PNG row. It's free, and the PDF never leaves your device.

How do I convert a JPG to PDF?

Drop the JPG, PNG or WebP into the converter, pick the PDF page size (the same size as the image, A4 or US Letter), then click Download on the PDF row. On A4 and Letter the picture fits inside half-inch margins, and wide pictures get a sideways page.

Is 300 DPI the same as 300 pixels per inch?

For sizing a print, yes. Strictly, PPI (pixels per inch) describes the image and DPI (dots per inch) describes the printer's ink dots, but photo editors and print shops use 300 DPI to mean 300 pixels per inch of paper. Either way, divide the pixels by 300 to get the print size in inches.

How big can a YouTube thumbnail be?

Up to 50 MB if you upload it from a computer, or 2 MB from the YouTube app on a phone. YouTube recommends 3840 × 2160 pixels (16:9) for video thumbnails and 2160 × 3840 for Shorts, at least 640 pixels on the short side, as a JPG or PNG. The limit was 2 MB everywhere until March 2026. Drop your thumbnail into the calculator to see the best quality that fits each limit.

Which is smaller, JPG, PNG or WebP?

WebP is usually the smallest, then JPG, then PNG. In our tests WebP was 25% to 50% smaller than JPG at the same quality setting, and a photo saved as PNG was around 10 times the size of a JPG at 85%. PNG still wins for screenshots, text and logos, where it stays perfectly sharp.

Is my image uploaded anywhere?

No. The calculator opens and re-saves your image inside your browser, so it never leaves your device. The copies you save also leave out the photo's hidden EXIF data, such as the camera and location.

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