How to do a take-off from a PDF drawing

A take-off (or quantity take-off) is the process of measuring the quantities of work from a set of drawings — the lengths, areas and counts a bill of quantities is built on. For decades that meant a scale rule, a printed drawing and a take-off pad. Today drawings arrive as PDFs, and in Corbel you measure straight off them on screen, with the quantities feeding a priced bill automatically.

This guide follows the real Corbel flow end to end — upload, calibrate, measure, price — and clears up a common misconception about where you start.

What is a PDF take-off?

Instead of measuring on paper, you upload the drawing PDF, calibrate it so Corbel knows the real-world scale, then draw your measurements directly on the page with the take-off tools. Each length, area or count you draw is captured as a quantity in the correct unit — metres, square metres, cubic metres or number.

The shift from paper isn't only speed. Because every measurement is a live object tied to a Condition— a type of work like "230mm external wall" — it can roll up across pages and price itself, with nothing re-keyed.

Before you start

You need very little up front:

• The drawing PDF— plans, sections and details for what you're measuring.
• A known dimension on each sheet— a printed scale bar or a figured grid dimension (say a 5 000 mm grid line) to calibrate against. Never trust the stated "1:100" on a PDF that may have been resized.

Optionally, set up your rate library under Assemblies— load the SA starter library or import a price list. That's the only thing worth doing ahead of time, and even it can wait until you're pricing: as you measure, each item links to a Condition, and every Condition pulls its materials and rates from a recipe in that library.

Step by step

New to it? Corbel can seed a "Demo — Sample house" project with a real 1:100 plan so you can practise on something safe. Otherwise, start a project of your own:

1. Create a project and upload the drawing

   Add a project, then upload the PDF. Corbel turns the file into pages you can open in the take-off viewer.

2. Calibrate the scale (press K)

   Open a page and pick the Calibrate tool (hotkey K). Click the two ends of a known dimension and type its real length and unit (mm, cm or m). Corbel works out the scale and locks it for that page. This is the one step you can't skip — measuring tools stay disabled until the page is calibrated.

3. Measure with the take-off tools

   Use Length (L) for linear work, Area (A) for surfaces, Polyline (P) for irregular runs, and Count (C) for items like doors. Trace walls, outline slabs, click each door. Finish an area or polyline with Enter; every Count click adds one.

4. Create a Condition (or let the wall wizard make one)

   Measurements attach to a Condition— a work type like "230mm external wall". You can add your own (name it and pick a type), or just start drawing and the wall wizard creates one and asks for its height, thickness and recipe. The recipe is optional — skip it to measure now and add pricing later; your quantities still roll up either way. Set it once and every measurement on that Condition inherits it.

5. Review the roll-ups

   Quantities accumulate per Condition and across every page. Sanity-check the totals as you go — a wall that should be ~40 m shouldn't read 400.

Getting accurate quantities

A take-off is only as good as its inputs. A few habits keep yours reliable:

For walls with doors and windows, use the Area tool's deduction mode to subtract openings — Corbel handles the deduction on the ASAQS net-wall convention. Work one trade or element at a time and lean on Conditions so identical items are measured the same way every time; consistent Conditions are what make a take-off auditable later.

From quantities to a priced bill

This is where measuring on screen pays off. Because each Condition links to a recipe, your quantities don't just sit in a register — they price themselves:

• The Materials tab totals your Conditions through their recipes into a material schedule and an openings schedule — and offers a one-click Draft BoQ.
• The Estimate · BoQ tab is the priced bill: ASAQS sections (preliminaries, measured work, provisional sums and more), your markup and VAT, in rands. You can freeze a snapshot to lock a version.
• Exports send the finished bill out as CSV, Excel or PDF — including an ASAQS BoQ template plus Xero, Sage, Procore and a measurements register.

For more on the output, read The ASAQS bill of quantities, explained. Still untangling the two halves of the job? See Take-off vs estimating.