NTS means not to scale — the view it labels is drawn for clarity rather than proportion, so you read the figured dimensions instead of measuring off the sheet.
NTS turns up under a detail title where a scale should be. Here is what it is telling you to do.
What NTS means
NTS means not to scale. The view it labels is not a true proportional reduction of the real thing, so you cannot lay a scale rule on it and get a number you can build to.
That is not an admission the drawing is wrong. The figured dimensions still govern, and so do the notes. What has been given up is the geometry, deliberately: a 10 mm sealant joint gets drawn three times too wide so you can see the backing rod inside it. A 6 m span gets drawn short with a break line so the detail fits the sheet – though strictly that is a broken view rather than an NTS one, since everything except the interrupted length is still to scale. That is why ISO dimensioning practice does not require a broken dimension to be marked out of scale. Both are useful drawings. Neither should be measured for the dimension it distorts.
Scope matters. NTS attaches to the view it sits under, not the whole sheet. One sheet can carry a plan at 1:100 with four NTS details beside it.
How it appears on a drawing
Most often in the scale position under a view title:
DETAIL 3 - SLAB EDGE AT WINDOW HEAD - NTS
In the title block scale box – normal for schematics and locality plans:
SCALE: NTS
On a mixed sheet, where a blanket scale is stated and exceptions called out:
SCALES 1:100 @ A1 U.N.O. - DETAILS A-C N.T.S.
You will see NTS, N.T.S. and nts. Same thing; the full stops are house style.
One related convention looks like a typo. Where a single dimension on an otherwise correct view is out of scale, ASME and ISO dimensioning practice underline that figure rather than declaring the whole view NTS. An underlined dimension is not emphasis. It means this figure does not match the drawn length; trust the figure. A dimension interrupted by a break line is the recognised exception and is not underlined.
Terms it gets confused with
- DO NOT SCALE – a standing note covering the whole sheet, and a much broader instruction. It appears on sheets that are to scale.
- An underlined dimension – one dimension out of scale on an otherwise true view.
- A broken view – a long item shortened by break lines. Everything but the interrupted length is to scale.
- DIAGRAMMATIC – the arrangement is indicative; routing or position may change on site. Common on services drawings.
- REF – a reference dimension, for information and not to be worked to.
- U.N.O. or U.O.N. – unless noted otherwise, what makes a blanket scale statement safe.
AU and UK versus US practice
Australian and UK sheets almost always carry a standing note – “do not scale from this drawing, use figured dimensions only” – alongside a ratio scale such as 1:20 or 1:100, qualified by paper size as 1:100 @ A1. NTS then marks the exceptions on a sheet that is otherwise honest. AS 1100 is the standard family behind Australian practice, and a scale is expected in the title block and under each view.
US architectural sheets state scales as imperial equivalents such as 1/4" = 1'-0" and use NTS the same way. Product and mechanical drawings on the ASME Y14 series lean on it less: the underline convention handles individual out-of-scale dimensions. ASME Y14.38 is the US abbreviations standard.
Where to check on your own drawing set
- The title block scale field, then the scale printed under each individual view.
- The abbreviations legend on the cover or general notes sheet.
- The paper size the PDF was issued at. A sheet drawn 1:100 at A1 and printed at A3 is effectively 1:200 – the most common way people scale off the wrong number. A scale bar survives that reduction; a stated ratio does not.
If a detail is NTS and the dimension you need is not figured, that is an RFI, not a measuring exercise. For the neighbouring abbreviations, our A-Z list of engineering drawing abbreviations covers the rest.
Other meanings of NTS
Outside drafting, NTS is widely used in messaging to mean “note to self”. It is also the Nevada Test Site, the National Trust for Scotland, and NTS Radio. None of these have anything to do with drawings, but they dominate general search results for the letters.