Measure PDF drawings for a tender: how to set the scale, areas and counts

The tender pack lands as a pile of PDFs and a Friday deadline. You need quantities, and you need them right.

Here's how to measure PDF drawings properly. Set the scale on each sheet, then check it against a printed dimension before you trust a single number.

Then measure lengths, areas and counts, and write each one down against the drawing it came from.

In short

• Open the PDF in a viewer with a measuring tool, such as Adobe Acrobat.
• Set the scale from the title block, for example 1:50, on every sheet.
• Check it: measure a dimension that's printed on the drawing. If the two don't match, stop.
• Measure lengths in metres, areas in square metres and count items one by one.
• Note the sheet and revision for every quantity, so you can check it later.

How do builders measure PDF drawings for a tender estimate?

Builders measure PDF drawings by setting the drawing's scale in a measuring tool. They check it against a known dimension, then click out lengths, areas and counts.

Each quantity goes on a takeoff sheet (a list of everything measured off the drawings), ready to price.

Here's the method, step by step:

1. List every sheet in the pack, with its number and revision.
2. Open one sheet and read the scale in the title block.
3. Set that scale in your measuring tool.
4. Measure a printed dimension to check the scale is right.
5. Measure the lengths: walls, skirting, pipe runs, cable routes.
6. Measure the areas: floors, ceilings, walls, roofs.
7. Count the items: doors, sockets, light points, radiators.
8. Write each quantity down with the sheet number it came from.

Check the scale first, every sheet, every time. One wrong scale makes every number on that sheet wrong.

How do you set the scale on a PDF drawing?

You set the scale by telling the measuring tool the ratio printed on the drawing, such as 1:50 or 1:100. The tool then turns your clicks on screen into real metres.

A scale is how much smaller the drawing is than the real thing. At 1:50, 1 centimetre on the drawing is 50 centimetres on site.

In Adobe Acrobat, the measuring tool sits under Measure objects. Pick a tool, right-click on the page and choose Change Scale Ratio and Precision. Then type the ratio from the title block.

Watch for sheets with more than one scale. A plan at 1:100 can have a detail at 1:20 on the same page. Reset the scale before you measure each part.

How do you check the scale is right?

You check the scale by measuring something with a dimension already printed on the drawing. If your measurement matches the printed figure, the scale is right.

Pick a long dimension, like the length of a whole wall. A long one shows a small error better than a door width does.

If the numbers don't match, something has changed the size of the drawing. Common causes are:

• the PDF was printed and scanned back in;
• someone printed it with Fit ticked, which shrinks a large page to fit the paper;
• the sheet was drawn at A1 but saved at a different page size;
• the scale in the title block is simply wrong.

If the scale won't check out, don't guess. Measure only from the printed dimensions on that sheet, and send a question to the architect.

How do you measure lengths, areas and counts?

You measure lengths with a distance or perimeter tool, areas with an area tool, and counts by marking each item as you go. Each kind of quantity gets its own unit.

In Acrobat, the Distance tool measures between 2 points. The Perimeter tool adds up a run of lines. The Area tool measures the shape you click round.

These match the units in NRM 2, the surveyors' rulebook from RICS for measuring building work in detail. A volume is just an area times a depth, so measure the area off the plan and take the depth from a section drawing.

For counts, put a mark on each item as you count it. Then you won't count the same socket twice, or miss the one behind the door symbol.

What rules do quantity surveyors use when measuring?

Quantity surveyors measure to the rules in NRM 2, so a bill of quantities follows the same method every time. You don't have to follow them on a small job, but they're a good habit.

The main rules in NRM 2 are:

• measure the work net, as it's fixed in position;
• the net figure includes extra material for laps and joints, and any waste;
• measure dimensions to the nearest 10 mm;
• give quantities to the nearest whole number, apart from tonnes;
• anything under 1 unit is given as 1.

On a priced bill, that means 17.28 m2 becomes 17 m2. When you build your own rate, you still allow for cutting and waste. Our guide to the bill of quantities shows how a bill lays these lines out.

What does a worked example look like?

Here's a worked example of measuring one room off a 1:50 floor plan. The room and figures are made up to show the method.

Step 1: check the scale.

The plan prints the room's long wall as 4,800 mm. With the scale set to 1:50, the Distance tool reads 4.80 m. The scale checks out.

Step 2: measure.

The room is 4.80 m by 3.60 m, and the section drawing shows a ceiling height of 2.40 m.

There's one door, 0.90 m by 2.10 m, and one window, 1.20 m by 1.20 m.

If the Distance tool had read 2.40 m for that 4,800 mm wall, the sheet would be at half size. You'd set the scale to 1:100 instead, then check it again.

Write the sheet number and revision next to every line. When the client asks what your price covered, you can show them.

What are the most common mistakes when measuring PDF drawings?

The most common mistakes are a wrong scale, measuring an old revision and missing part of the pack. Each one can lose you the job's margin.

Many drawings carry a "do not scale" note. That means the written dimensions win over anything you measure. NRM 2 even expects tender documents to say who is responsible for scaled dimensions.

So if a key dimension isn't printed, scale it if you must, but say so in your tender. Write it down as an assumption, or price it as a provisional sum (an allowance for work that can't be fully priced yet).

Can you measure PDF drawings for free?

Yes, you can measure PDF drawings for free if the file allows it. Adobe's free Acrobat Reader has the measuring tools, but only when the person who made the PDF has switched measuring on.

If the tools are greyed out in Reader, you have 3 options:

1. Ask the architect for a PDF with measuring enabled.
2. Use a paid PDF editor or takeoff software.
3. Measure only from the printed dimensions.

Paid takeoff tools add things like saving your measurements, colour-coding each trade and exporting to a spreadsheet. Our guide to construction estimating software explains the different types and how you pay.

Once you've got your quantities, how to price a job shows how to turn them into a price that covers every cost.

Where Nexley fits

Nexley is AI software for UK tradespeople and small construction firms that prices tenders, measures take-offs and writes quotes. It also runs the back office through WhatsApp, linked to Xero, QuickBooks and Sage.

Nexley measures your PDF drawings and builds a bill of quantities from them, priced on your own rates.

It itemises every line against the drawing it came from, so you can trace a figure back and correct it. The checking stays with you. See how the takeoff software that turns drawings into a bill of quantities works, or try it free for 7 days.

Common questions

Can you measure on a PDF drawing in Adobe?

Yes. Adobe Acrobat has a Distance, Perimeter and Area tool under Measure objects. Set the scale first with Change Scale Ratio and Precision, then click out what you need.

Acrobat can export the measurements to a spreadsheet file. In the free Reader, the tools only work if the PDF's creator has enabled them.

How do you measure a PDF drawing if it has no scale?

Use a printed dimension instead. Measure a line whose length is written on the drawing, then work out the ratio from that.

If nothing on the sheet has a dimension, you can't measure it reliably. Ask the architect for a scaled drawing, or list what you need as questions before you price.

Is it OK to measure from a printed copy of a PDF?

Only if you know it printed at actual size. Printing with Fit ticked shrinks a large drawing onto smaller paper, so a scale rule will read short.

Check a printed dimension with your scale rule first. If it's out, measure on screen instead.

How do you measure PDF drawings on an iPad or phone?

Some PDF apps for tablets and phones have measuring tools, but check the scale just as carefully. A small screen makes it easy to click the wrong line.

For a full tender, a laptop or desktop with a bigger screen is quicker and more accurate. Use the phone for a quick check on site.

Sources

This page is general guidance. Always check the drawings, specification and tender rules for the job you're pricing, and ask the architect when something doesn't add up.

• Grids, guides and measurements in PDFs (Adobe Acrobat Help) (helpx.adobe.com)
• Scale or resize printed pages in Acrobat and Reader (Adobe Help) (helpx.adobe.com)
• NRM 2: Detailed measurement for building works, 2nd edition (RICS) (rics.org)
• Measuring scaled PDF plans and drawings (North Norfolk District Council) (north-norfolk.gov.uk)