PDF & Files

PDF File Size Calculator

Part 1

Estimated PDF size

No file needed. Describe the document and get an estimate with a likely range.

Start from a typical document

Presets fill in typical values. Every field stays editable - use your own figures.

Pages

Number of pages

Image-heavy pages

Share of pages that are mostly pictures or scans. The rest are counted as text pages.

Images

Images per image-heavy page

Describe image size by

Image resolution

DPI

72-96 screen, 150 good on-screen and office print, 300 print and scans.

Page size

Each image covers

% of the page

100% for a full-page scan.

Colour

Image compression

Black-and-white images are never stored as JPEG; any JPEG choice is treated as CCITT/JBIG2-style lossless for them.

Fonts

Embedded fonts

Count each weight and style separately: regular, bold and italic are three fonts.

Font embedding

Estimated PDF size

1.21 MB

Roughly 1,207.6 KB (range 601.3 KB - 2,460.2 KB)

An estimate from typical figures. Upload a real PDF below to see its actual size.

Likely low end

601 KB

Likely high end

2.46 MB

Average per page

60.4 KB

Images

1.09 MB

Text and page structure

65.0 KB

Embedded fonts

50.0 KB

Image-heavy pages

Pixels per image

1.09

Megapixels

A PDF’s size depends on what is in it, not just how many pages it has. Treat 1,207.6 KB as a middle estimate: files built like this usually land between 601.3 KB and 2,460.2 KB.
Images dominate. Busy photos compress less than diagrams or mostly-white scans, and many PDF writers downsample or re-encode images, so the images you put in are not always the images stored.

Show the formula with your numbers

image-heavy pages = round(20 × 25%) = 5; text pages = 15
pixels per image = (8.27 in × 150) × (11.69 in × 150) × 50% = 1,087,608
bytes per image = 1,087,608 px × 3 byte/px × 1/15 (compression) = 217,522 bytes
images = 5 pages × 1 × 217,522 = 1,087,608 bytes
text and structure = 15 × 3,000 + 20 × 1,000 = 65,000 bytes
fonts = 2 × 25,000 = 50,000 bytes
total = 1,087,608 + 65,000 + 50,000 + 5,000 (document overhead) = 1,207,608 bytes

Part 2

Actual PDF size

Have the PDF already? Drop it here to see its real size, pages and bytes per page.

Choose a PDFOne file. Drag and drop, or click to browse.

Your file is processed locally in your browser and is not uploaded. Only its size and page count are read.

Free to useNo sign-up requiredNo watermarkRuns in your browser

Upload portals, email servers and exam systems all set file size limits, and it helps to know before you scan 60 pages at 600 DPI whether the result will fit. The first part of this tool estimates a PDF’s size from what goes into it: how many pages, how many of them are pictures, the image resolution and colour, the compression, and the fonts.

The second part is separate: drop in a real PDF and it shows the actual file size, page count and bytes per page, and compares it with an estimate if you have one. A PDF’s size depends heavily on its content, so the estimate comes with a low-high range and every assumption is shown. Your file is processed locally in your browser and is not uploaded.

How this tool works

Estimate: enter the document
Pages, share of image-heavy pages, images per page, resolution or pixel size, colour and compression.
Add fonts
How many fonts are embedded and whether they are subset (the usual case) or full.
Read the estimate and range
The middle estimate, a likely low and high, and the working behind it.
Actual: drop a real PDF
See its true size, pages and average bytes per page, optionally against your estimate.

How it works

Images are usually most of a PDF’s size. Pixels per image come from the resolution and the area the image covers (page width × DPI × page height × DPI × coverage), or from pixel dimensions you enter. Uncompressed, a colour pixel is 3 bytes, greyscale 1 byte and black-and-white 1 bit. Compression then shrinks that: roughly to a tenth for JPEG quality ~90, a fifteenth for ~75, a twenty-fifth for ~50, and about half for lossless Flate on photographs.

Text is cheap. A text-heavy page adds about 3 KB of compressed drawing instructions, and every page adds about 1 KB of structure. Embedded fonts add roughly 25 KB each when subset (only the characters used) or around 250 KB for a whole Latin font file. About 5 KB covers the header, catalogue and cross-reference table.

Because real content varies so much, the range multiplies each part by its own spread: images from half to double for JPEG, text from half to double, fonts from 0.4× to 3×. Use the range, not the single figure, when a limit is close.

Common use cases

Choosing a scan resolution and colour mode that keeps a document under an upload limit.
Working out whether a photo-heavy brochure will fit in an email attachment.
Checking whether a real PDF is unusually large for its page count before compressing it.
Explaining to a client why a 10-page scan is 20 MB and a 100-page report is 1 MB.

Typical sizes per page

Rough, content-dependent figures per A4/Letter page
Text only, subset fonts	3-10 KB per page (plus fonts once)
Black-and-white scan, 300 DPI	30-100 KB
Greyscale scan, 300 DPI, JPEG	300-800 KB
Colour scan, 300 DPI, JPEG	0.8-2.5 MB
Full-page photo, 150 DPI, JPEG	150-450 KB

Making a PDF smaller

Scan text documents in black and white or greyscale, not colour.
150 DPI is plenty for on-screen reading; 300 DPI is for print and OCR.
Subset fonts rather than embedding whole font files.
Compress an existing PDF: Compress PDF re-encodes its images and leaves text sharp.

Formula

Pixels per image

page width (in) × DPI × page height (in) × DPI × coverage %

Or width × height in pixels.

Bytes per image

pixels × bytes per pixel (3 colour, 1 grey, 1/8 B&W) × compression ratio

Text and structure

text pages × 3,000 + all pages × 1,000 bytes

Fonts

fonts × 25,000 (subset) or 250,000 (full) bytes

Estimated size

images + text and structure + fonts + 5,000 bytes

Bytes per page (actual)

file size ÷ page count

Worked examples

A 10-page greyscale scan

10 A4 pages at 300 DPI in greyscale with JPEG ~75: each page is about 8.7 million pixels, 8.7 MB uncompressed, about 580 KB compressed - roughly 5.8 MB in total, likely between 3 and 12 MB.

A 20-page report with a few photos

5 pages each with one colour photo covering half an A4 page at 150 DPI, 15 text pages and 2 subset fonts: about 1.2 MB. A real 20-page PDF of 1.1 MB is 55 KB per page - right where the estimate expects.

Frequently asked questions

How accurate is the estimate?

It is an informed estimate, not a prediction. Two images with the same resolution and JPEG quality can differ several-fold in size depending on detail, and PDF writers may downsample or re-encode images. The low-high range is the honest answer; upload a real file for the actual figure.

Is my PDF uploaded when I check its actual size?

No. Your file is processed locally in your browser and is not uploaded. Only its size and page count are read.

Why is my scanned PDF so large?

Every scanned page is a full-page image. At 300 DPI in colour that is about 26 MB of raw pixels per A4 page before compression. Greyscale or black-and-white, a lower DPI, or stronger JPEG compression all cut it sharply.

Do fonts really matter?

Usually a little: a subset font is tens of kilobytes. Whole embedded fonts, especially Chinese, Japanese or Korean ones, can add megabytes - which is why most software subsets them.

Are KB and MB 1,000 or 1,024 here?

The estimate uses decimal units (1 KB = 1,000 bytes), as most upload limits do. The actual-size panel shows the exact byte count as well.