Taking off vs working from a PDF BOQ
Taking off is measuring quantities yourself from drawings and specifications. Working from a PDF BOQ means pricing the quantities the client's quantity surveyor issued. Pricing the issued bill is faster and is usually what a bill-based tender requires; taking off is slower but lets you check quantities, price packages or tender without a bill.
By BOQ Estimator. Published .
Two sources of quantities, two kinds of risk
On a bill-based tender you normally enter prices against the client's quantities, and the bill is the document you return. Those quantities were measured by someone else and can contain errors. How much that matters depends on the contract: a remeasurement contract pays for what is built, while a lump sum on a firm bill treats quantities differently.
Estimators usually combine the two: price the bill, and take off selectively where value or risk justifies the time. Errors and omissions covers what to do with the differences you find.
Set a time budget before you start. Decide how many hours the checks may take, which items get them, and what size of difference is worth a query. A check that cannot change a decision is not worth the time, and small differences are often rounding or a different method of measurement.
If you measure from a PDF drawing, set the scale from a known dimension, confirm it against a second dimension, and record the drawing number and revision with each measurement. Mark up a copy, never the issued drawing.
General information. This is not contract advice. How quantities are treated is set by the contract, so read its measurement and error provisions.
Step by step
Deciding how much to measure yourself
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Read how the contract treats quantities
Remeasured, lump sum on a firm bill, or approximate quantities? That decides how much weight the printed figures carry.
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Convert the bill and sort it by amount
Put the bill in a sheet and rank items by value or by uncertainty. In most bills a small share of the items typically carries most of the money.
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Take off the top items
Measure the biggest or most uncertain items from the drawings, to the same measurement rules as the bill, and compare.
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Run sanity checks on the rest
Floor area x thickness against concrete m³, wall areas against finishes, counts against door and window schedules, overall areas against the gross floor area. A large gap is a reason to measure that item properly.
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Log differences as queries
Do not edit the issued quantities. Raise the difference with the item number and your measurement, and keep your workings so the query can be checked.
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Take off in full where there is no bill
That means design-and-build tenders, sub-contract enquiry packages and bills marked approximate or provisional.
Side by side
Taking off and pricing the issued bill compared
| Point | Taking off | Pricing the issued bill |
|---|---|---|
| Source of quantities | Your own measurement from drawings and specification. | The client's quantity surveyor. |
| Time | Long; grows with the number of drawings. | Short; grows with the number of items. |
| Main risk | Your own measurement error, or a missed drawing. | An error or omission in the client's bill. |
| Return format | Your own format, or a bill you build. | The issued bill, with the same numbers and order. |
| Best used when | There is no bill, for packages, or to check high-value items. | A bill is issued and the instructions require it to be priced. |
| Units and rules | Yours, unless you adopt the bill's method. | Fixed by the bill; rates are built to them. |
Watch for
What goes wrong when you measure against a bill
- Different measurement rules. Your net quantity and the bill's may differ by method. Compare like with like.
- Silent overrides. Replacing the bill's quantity with yours in the returned document is not what the instructions normally allow.
- Drawings revised after the bill. Check the revision on each drawing against the bill's list.
- Scale errors. On-screen measurement from a PDF depends on the drawing scale. Check a known dimension first.
- Time spent on small items. Measure by value, not by order in the bill.
- Treating the bill as the drawing. The bill is derived data. When they disagree, raise a query rather than choosing.
- No record of the measurement. A difference you cannot show is hard to raise. Keep dimensions, calculations and drawing references with the query.
The tool
How BOQ Estimator helps
BOQ Estimator is for the second route. It reads the issued bill PDF into a sheet with item counts, section totals and flags, so you can sort by value and pick what to check. It does not measure from drawings, and its tie-out confirms the sheet matches the document, not that the document matches the drawings. Try it on the BOQ to Excel converter. Free: 1 file per day, up to 10 pages, no account. Files over 10 pages are converted up to page 10 on the free allowance; a page code converts the whole file, up to 150 pages. See plans and limits.
Related
Related guides
FAQ
Questions estimators ask
What is taking off in quantity surveying?
Measuring quantities from drawings and specifications, recording the dimensions and calculations, then grouping them into items. It is the stage before a bill of quantities is written.
Do contractors take off quantities on a bill-based tender?
Often only in part. Most price the issued quantities, and measure selectively to check high-value items, price packages or cover areas where the bill is approximate.
How do I check a bill's quantities quickly?
Test the big items against simple relationships: area x thickness for concrete, perimeter x height for walls, counts against schedules, and overall areas against the gross floor area.
Can I measure from a PDF drawing on screen?
Yes, if the drawing is to scale and the scale is set correctly. Check a known dimension first, and confirm the revision matches the one the bill was prepared from.
What if my quantities differ from the bill?
Raise a query with the item number and your workings. Keep pricing the issued quantity unless the instructions say otherwise, and keep the reply.
What does approximate quantities mean?
The printed quantities are estimates and the work will be remeasured, so the rates matter more than the quantities. Read the preambles for how remeasurement is done.
Can BOQ Estimator take quantities off drawings?
No. It reads the issued bill PDF into Excel and checks the sheet against the document's own subtotals. It does not measure drawings.