Supported Paper Sizes

Werk24 supports automated processing for technical drawings up to a maximum size of A0. Beyond that the API returns a DRAWING_PAPER_SIZE_TOO_LARGE exception.

How the limit is applied depends on how the page is made, and the difference is larger than it sounds:

• Vector PDFs carry no pixels of their own, so there is no pixel ceiling to exceed. We rasterise them ourselves at a resolution we choose.
• Image uploads (PNG, JPEG, TIFF, and HPGL renders) are measured by pixel count, because an image states no physical size. The long edge must stay under roughly 15,000 px, which is an A0 at just over 300 DPI. Every size in the resolution guide fits under it.
• PDFs are not measured this way at all, including a drawing scanned into a PDF. See the acceptance rules below for what that means in practice.

For optimal results, ensure your drawings conform to the supported dimensions below and follow the best practices in this guide.

Acceptance Rules (Exactly How We Decide)

For a PDF, vector or scanned, the page states its own size in millimetres. Nothing rejects it for being oversized today: the pixel ceiling below is applied when an image is imported, and a PDF page is never imported that way. A sheet beyond A0 sent as a PDF is therefore processed rather than refused, and A0 remains the largest sheet the extraction is designed and supported for. Keep to A0.

For an image upload there is no stated size, so the sheet is inferred from the pixel count: a long edge implying more than about 320 DPI on an A0 is presumed to be a larger sheet and rejected with DRAWING_PAPER_SIZE_TOO_LARGE. That works out to roughly 15,000 px.

The inference is approximate, and it cuts both ways. A small sheet scanned very finely reads as a large one, because pixel count is the only size signal a raster carries. Each sheet has its own resolution at which it trips the ceiling:

sheet	refused at or above
A4	1,284 DPI
A3	908 DPI
A2	642 DPI
A1	454 DPI
A0	321 DPI

The one worth knowing is A1: a 600 DPI A1 scan is rejected, and 600 DPI is a common scanner default. If you hit DRAWING_PAPER_SIZE_TOO_LARGE on a sheet you know is within the limit, this is why. Re-scan at 300 DPI.

Supported and Unsupported Paper Sizes

A0 and smaller are supported. US sizes are accepted when their physical dimensions fall within A0.

Why There Is a Cap at All

• Feature density: a sheet beyond A0 carries hundreds of callouts and dense leader networks, and precision falls off faster than sheet area grows.
• Runtime predictability: bounding page geometry keeps throughput consistent across queueing, OCR and geometry analysis.

A0 is a recent increase from A1. If you have retiled A0 masters into A1 sheets to work around the old limit, you no longer need to.

Relation to DPI (Resolution)

Paper size and DPI are independent constraints:

• Both constraints apply, and for raster inputs they pull in opposite directions: text needs pixels, and the size check caps how many a raster may have.
• See Resolution Limitations for the pixel targets per sheet size, the upper ceiling, and export tips.

Sizing targets at 200 DPI, the point at which the smallest text clears roughly 10 pixels: A4 ≈ 1654×2338, A3 ≈ 2338×3307, A2 ≈ 3307×4677, A1 ≈ 4677×6622, A0 ≈ 6622×9362. 300 DPI is better, and every size above fits under the raster ceiling at 300 DPI. These are targets, not the API's rejection threshold. See the resolution page for what is actually enforced.

Scaling, Plot Ratios & Common Pitfalls

• ❌ Printing A0 down to A3 to “fit limits” is no longer necessary, and never helped: it shrinks text and symbols and often breaks OCR.
• ❌ “Fit to page” exports can distort the intended scale.
• ✅ Export at the intended paper size, no scaling, and keep within A0.

If your master is larger than A0: Split it into A0 or smaller sheets by view zone or assembly section, keeping title blocks and cross-references consistent.

Vector PDFs vs. Raster Files

• Vector PDF is preferred. Page size is determined by the PDF page box and border geometry.
• Images (PNG, JPEG, TIFF): The paper size is inferred from pixel count alone, not from the border or title block. Both the size ceiling and the resolution check apply here, and only here.
• Scanned and hybrid PDFs: Neither check runs, because the input is a PDF. The page is still a grid of pixels, so the resolution guidance applies to it in full even though nothing enforces it. Keep vector primitives whenever possible.

Multi-Sheet & Mixed Sizes

• Per-sheet evaluation: each page is handled independently, so one oversized page does not affect the rest.
• Best practice: keep all sheets ≤ A0 and use consistent orientation, border thickness and title block placement across the set.

FAQ

Q: Are US/ANSI sizes allowed? A: Yes. ANSI E (864 × 1118 mm) and everything below it fall within A0.

Q: My A0 used to be rejected. Has that changed? A: Yes. The cap was A1 and is now A0. If you retiled A0 masters into A1 sheets to work around it, you no longer need to.

Q: Does the size limit change if my drawing is vector? A: A0 is the supported limit for both. The pixel ceiling is only ever applied to image uploads, so no PDF is at risk of it, vector or scanned.

Q: What about very long custom sheets (e.g., 297 × 1200 mm)? A: Judged against A0's dimensions (841 × 1189 mm), so 1200 mm on the long edge is over. Use multiple sheets.

Q: One page in my multi-page PDF is oversized. Will the whole file be rejected? A: No, only that page. Best practice is to separate or fix the offending page.

Best-Practice Checklist

• [ ] Keep every sheet A0 or smaller (≤ 841 × 1189 mm).
• [ ] Prefer vector PDF export from CAD; avoid “fit to page”.
• [ ] For masters larger than A0, tile into A0 or smaller with clear cross-refs.
• [ ] Pair with ≥ 300 DPI for raster content (see Resolution guide).
• [ ] Maintain full borders/title block (helps size inference).
• [ ] Use consistent layout, orientation, and title block across all sheets.

If you still encounter DRAWING_PAPER_SIZE_TOO_LARGE after following this guide, share a sample (redacted if needed) and the export settings. We’re happy to help you pick the best tiling/export strategy.