Estimate how much space your PDFs need — and how many fit in any drive or cloud plan
For scanned documents: Low is a typical 150 to 200 DPI color scan, Medium is a typical 300 DPI color scan, and High is a 600 DPI color scan. For black and white scans, choose Text Only.
The PDF storage calculator above turns two simple numbers — how many files you have and how big each one is — into the total disk or cloud space you need, plus how many of those files fit in common storage sizes. It runs entirely in your browser; nothing is uploaded. Use it to plan a backup drive, size a cloud plan, budget a scanning project, or answer questions like "how many PDFs fit in 50 GB?"
Total storage always comes down to one formula: average file size × number of files. The hard part is estimating the average file size, because a PDF's size depends far more on its content than its page count. The calculator uses realistic per-page averages for each content type and quality level so you get a dependable range without having to open a single file.
Average file size is page count multiplied by the size of one page. Size per page varies enormously by content type:
| Content Type | Size per Page (Medium) | 10-Page File | Typical Documents |
|---|---|---|---|
| Text Only | ~50 KB | ~0.5 MB | Contracts, letters, plain reports |
| Mixed Content | ~200 KB | ~2 MB | Business reports, presentations, invoices |
| Image-Heavy | ~500 KB | ~5 MB | Catalogs, portfolios, brochures |
| Scanned (300 DPI, color) | ~500 KB | ~5 MB | Scanned contracts, archives, records |
These are typical sizes for one letter-size scanned page saved as a PDF. They come from our own test scans of a letter with text and a small photo (JPEG compression for color and grayscale, CCITT Group 4 compression for black and white) and from the file sizes ScanSnap publishes for its scanners. Real scanners vary with the page, the scanner and its compression setting, so treat these as typical ranges, not exact sizes.
| DPI | Color | Grayscale | Black and white |
|---|---|---|---|
| 150 | 150–300 KB | 150–300 KB | About 20 KB |
| 200 | 200–450 KB | 200–450 KB | About 25 KB |
| 300 | 350–650 KB | 350–600 KB | 30–150 KB |
| 600 | 0.9–1.7 MB | 0.8–1.9 MB | 50–500 KB |
Grayscale saves only about 10 percent compared with color. Black and white is the big saving: for text documents it was about 90 percent smaller than color in our tests (80 to 95 percent, depending on the scanner). Resolution matters too: a 150 DPI scan is about 40 percent of the size of a 300 DPI scan, and a 600 DPI scan is about 5 to 8 times the size of a 150 DPI scan. ScanSnap scans black and white at a higher DPI than color, which is why the top of the black and white range is much larger than our own results. Scan figures last reviewed October 2026.
This is the reverse question: given a capacity, how many files fit? Divide the capacity by your average file size. Here is a quick reference at 2 MB per average PDF (a typical 10-page mixed document). For pages rather than files, see How many pages is 1MB PDF?
| Capacity | Files at 50 KB | Files at 2 MB | Files at 5 MB (scans) |
|---|---|---|---|
| 1 GB | ~20,000 | ~512 | ~205 |
| 15 GB (Drive free) | ~307,000 | ~7,680 | ~3,072 |
| 50 GB | ~1,024,000 | ~25,600 | ~10,240 |
| 100 GB | ~2,048,000 | ~51,200 | ~20,480 |
| 1 TB | ~20,970,000 | ~524,000 | ~209,700 |
The calculator returns three numbers and a fit table:
Example 1 — Exporting 30,000 emails to PDF: mostly text with the occasional attachment, so mixed content at roughly 2 MB each. 30,000 × 2 MB = 60,000 MB ≈ 58.6 GB. That will not fit Google Drive's 15 GB free tier but fits comfortably on a 128 GB drive with room to grow.
Example 2 — A 5,000-document scanning project: 20 pages each, scanned at 300 DPI in color (~0.5 MB/page = 10 MB/file). 5,000 × 10 MB = 50,000 MB ≈ 48.8 GB. Scanning at 150 DPI instead (about 40 percent of the size) cuts this to about 20 GB, and scanning in black and white at 300 DPI (30 to 150 KB per page) cuts it to about 3 to 15 GB.
Example 3 — A law firm's case archive: 200,000 mixed PDFs averaging 1.5 MB. 200,000 × 1.5 MB = 300,000 MB ≈ 293 GB. With a 25% buffer, provision about 370 GB — a 512 GB drive or a 1 TB cloud plan.
These examples use the same formula as the calculator above (pages × size per page × quality) with three common document types at medium quality. The per-page sizes come from the average PDF file size table on the PDF File Size Calculator. Each cell shows the total, then the total with the 25% growth buffer.
| Number of Files | 1-page invoice (205 KB each) | 10-page text report (512 KB each) | 20-page business report (4.0 MB each) |
|---|---|---|---|
| 100,000 | 19.53 GB (24.41 GB with buffer) | 48.83 GB (61.04 GB with buffer) | 390.63 GB (488.28 GB with buffer) |
| 300,000 | 58.59 GB (73.24 GB with buffer) | 146.48 GB (183.11 GB with buffer) | 1.14 TB (1.43 TB with buffer) |
| 1,000,000 | 195.31 GB (244.14 GB with buffer) | 488.28 GB (610.35 GB with buffer) | 3.81 TB (4.77 TB with buffer) |
Example 4 — 100,000 invoices: each invoice is 1 page of mixed content (text with a logo), so 0.2 MB per file. 100,000 × 0.2 MB = 20,000 MB ≈ 19.53 GB. With the 25% buffer, plan for about 24.41 GB, which is more than Google Drive's 15 GB free tier but fits on a 50 GB plan.
Example 5 — 300,000 text reports: 10 pages of text each, so 0.5 MB per file. 300,000 × 0.5 MB = 150,000 MB ≈ 146.48 GB. With the 25% buffer, plan for about 183.11 GB, which fits on a 256 GB drive.
Example 6 — 1,000,000 business reports: 20 pages of mixed content each, so 4 MB per file. 1,000,000 × 4 MB = 4,000,000 MB ≈ 3.81 TB. With the 25% buffer, plan for about 4.77 TB, which needs a 5 TB or larger drive or cloud plan.
Scanned page sizes come from our own test scans and from the file sizes ScanSnap publishes for its scanners (see the scan size table above). Other per-page size averages are derived from typical PDF output at each content type and quality level, consistent with common scanner DPI behavior (a 300 DPI letter page ≈ 8 megapixels) and standard PDF image compression. Storage units use binary conversions (1 GB = 1,024 MB) to match how operating systems and drives report free space. Cloud free-tier sizes (Dropbox 2 GB, iCloud 5 GB, OneDrive 5 GB, Google Drive 15 GB) reflect published consumer plans. Estimates are for planning and may differ from exact byte counts, which depend on fonts, embedded media, and the tool used to create each file. Last reviewed: July 19, 2026.
It depends on content and page count. A text-only PDF averages about 50 KB per page, a mixed text-and-image PDF about 200 KB per page, and a scanned document about 350 to 650 KB per page at 300 DPI in color (about 30 to 150 KB in black and white). So a typical 10-page mixed PDF is around 2 MB, and 1,000 of them need about 2 GB. Multiply your average file size by the number of files to get total storage.
1 GB holds roughly 500 average PDFs of 2 MB each, about 20,000 one-page text PDFs at 50 KB each, or as few as 700 image-heavy pages at 1.5 MB each. Divide the capacity by your average file size: 1 GB is 1,024 MB, so at 2 MB per file that is 512 files.
50 GB is 51,200 MB. At 2 MB per average PDF that is about 25,600 files; at 500 KB per file about 102,400 files; at 5 MB per scanned file about 10,240 files. Use the calculator above to get the exact count for your file size.
Estimate the average size of one PDF (pages multiplied by size per page for your content type), then multiply by how many files you have. For example, 30,000 files averaging 2 MB each need 60,000 MB, which is about 58.6 GB. Add a 20-30% buffer for growth when planning real storage.
At 2 MB per average PDF, 10,000 files need about 20 GB. If they are one-page text documents at 50 KB, only about 500 MB. If they are scanned at 300 DPI averaging 5 MB, about 50 GB. The content type matters far more than the file count.
A scanned page is a full photo of the page, not selectable text. At 300 DPI a letter-size page is roughly an 8-megapixel image, about 350 to 650 KB per page in color, and at 600 DPI about 0.9 to 1.7 MB per page. Scanning text documents in black and white saves the most (about 90 percent smaller than color in our tests), scanning at 150 DPI helps, and compressing the PDF helps too: in our tests, a scanned PDF became 54 to 92 percent smaller depending on the level. Results vary by file.
Common free tiers are Dropbox 2 GB, iCloud 5 GB, OneDrive 5 GB, and Google Drive 15 GB. At 2 MB per average PDF, Google Drive free holds about 7,500 files and Dropbox free about 1,000. Compare your calculated total against those limits, and compress or upgrade if you exceed them.
Compress PDFs after creation (in our tests, PDFs with photos became 90 to 98 percent smaller, scanned PDFs 54 to 92 percent smaller and text-only PDFs about 20 percent smaller; results vary by file), scan text documents in black and white (about 90 percent smaller than color in our tests, while grayscale saves only about 10 percent), scan at 150 DPI instead of 300-600 for text documents, remove duplicate files, and store archival copies at lower quality. Compressing a 50 GB library by an average 40% frees roughly 20 GB.
For text-only pages at about 50 KB each, roughly 20,000 pages per GB. For mixed text-and-image pages at 200 KB each, about 5,000 pages per GB. For 300 DPI color scans at about 0.5 MB per page, about 2,000 pages per GB, and many more if you scan in black and white.
It gives a planning estimate, not an exact byte count. Real PDF sizes vary with fonts, embedded images, compression, and how the file was created. The per-page averages used here reflect typical documents at each quality level, so treat the result as a reliable range for budgeting storage rather than a guaranteed figure.
It depends on the size of each file. Using this calculator's medium-quality estimates, 300,000 one-page invoices (about 205 KB each) need about 58.59 GB, 300,000 ten-page text reports (about 512 KB each) need about 146.48 GB, and 300,000 twenty-page business reports with charts (about 4 MB each) need about 1.14 TB. Add a 25% growth buffer when you plan storage: about 73.24 GB, 183.11 GB, or 1.43 TB.
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