What to do when a plan set has no stated scale
Practical ways to establish scale on a drawing marked NTS or missing its scale note, using dimension strings, survey data, standard widths and known objects.
5 min read
Key takeaways
- NTS and missing scale notes do not prevent takeoff — they prevent assumption.
- Any dimensioned element on the sheet can serve as a calibration reference.
- Standard object widths are a fallback, not a first choice.
- Document the reference you used and flag the assumption in your bid.
Sooner or later you get the sheet: a sketch from a developer, a marked-up exhibit, a page pulled out of a larger set, or a drawing stamped NOT TO SCALE that is nonetheless the only document showing the work. You still have to bid it. Here is how to do that responsibly.
Look for any dimension on the sheet
A drawing without a scale note frequently still contains dimensioned information. Any of these can anchor calibration:
- A dimension string anywhere on the sheet, even in a detail on the same view.
- Property line bearings and distances from the survey.
- Station labels along an alignment (STA 10+00 to 12+00 is 200').
- Pipe callouts giving a length: "142 LF of 15" RCP".
- A building footprint whose dimensions appear on the architectural plans.
- A north arrow with a graphic scale bar, even if the note is missing.
Fall back to standard geometry, carefully
When no dimension exists, standard object sizes give an approximate scale. Treat these as estimates, and prefer several agreeing references over one.
| Object | Typical dimension | Caution |
|---|---|---|
| Parking stall | 9' x 18' | Varies by jurisdiction; 8.5' and 20' both occur |
| Drive aisle (two-way) | 24' | Fire access may require more |
| ADA stall plus aisle | 8' + 5' or 8' + 8' | Van accessible differs |
| Residential street | 26'–32' face to face | Highly local |
| Standard door | 3'-0" | Building sheets only |
| Sidewalk | 5' | Often 4' residential, 6'–8' commercial |
Two independent references that agree within a couple of percent is reasonable confidence. Two that disagree by 20% means the sheet has been scaled non-uniformly, or one of your assumptions is wrong — resolve it before measuring.
Watch for non-uniform scaling
Occasionally a PDF has been stretched in one direction, usually by a bad export or a scan on a misfed page. Check by calibrating on a horizontal reference and then verifying a vertical one. If the two disagree systematically, measure with the axis-appropriate factor if your tool allows it, or request a clean file.
Document the assumption and price the risk
- Record which reference you used, its assumed real length, and the resulting scale.
- Note the assumption on the affected line items rather than burying it.
- State a clarification in your proposal: quantities based on scaled measurements from an unscaled drawing.
- Ask for a dimensioned or scaled sheet — most of the time it exists and nobody sent it.
The goal is not certainty; it is transparency. A number derived from a stated reference can be reviewed, corrected and defended. A number derived from a guess nobody wrote down cannot.
Doing this work in TakeoffAI? Scale calibration.
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