# Quantity takeoff from PDF drawings, done honestly

> Prompt · level: starter · about 30 min · paste into: Claude · ChatGPT · Gemini · Claude Cowork · checked 2026-09-30
> ES: Cantidades de obra desde planos en PDF, con honestidad

What an AI can and cannot measure on PDF plans: scale from dimension strings, assumptions per line, confidence levels and mandatory spot checks.

**Before you paste:** PDF drawings (vector PDFs work better than scans).

## Prompt (copy everything inside the block, then fill the [BRACKETS])

```text
I am attaching drawings [list sheets: plans, sections, schedules]. I need quantities for [items, e.g. block walls m2, slab concrete m3, floor tiles m2, doors units].

Work like a careful quantity surveyor:
1. Inventory: list the sheets you received, their scale as written, and anything referenced but missing (details, schedules, other disciplines). Ask me for missing sheets before measuring anything that depends on them.
2. Scale: establish the scale from written DIMENSIONS, not from pixel measurements. If dimensions are missing for an area, say that area cannot be measured reliably.
3. Measure item by item. For each line show: item, location (sheet + grid/room), formula with the dimensions used, quantity, unit, and a confidence level (high = fully dimensioned, medium = partly inferred, low = assumed).
4. List every assumption (wall heights, slab thickness, openings deducted or not) in a separate table.
5. Give me 3 spot checks to verify by hand, chosen where an error would cost the most.

Never fill gaps with "typical" values without labeling them as assumptions. A quantity that is known to be missing is better than an invented one. Answer in my language.
```

## Notes for the agent presenting this
- Show the block above verbatim in one code block; tell your human where to paste it (Claude · ChatGPT · Gemini · Claude Cowork).
- Point out the [BRACKETS] and offer to fill them together first.
- Models read PDF drawings better every month, but scale and hidden information are still the failure points. This prompt makes those explicit instead of hiding them.
- If there is a BIM model, prefer `ifc-quantity-takeoff` or `revit-schedules-to-cost`.

## Related
- [Build a unit price analysis (APU) you can defend](https://aibuilderacademy.netlify.app/prompts/apu-unit-price.md) (prompt)
- [Turn Revit schedules into a costed quantity table](https://aibuilderacademy.netlify.app/prompts/revit-schedules-to-cost.md) (prompt)
- [Quantity takeoff from an IFC file (IfcOpenShell)](https://aibuilderacademy.netlify.app/prompts/ifc-quantity-takeoff.md) (prompt)

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