How to set drawing units before inserting a downloaded block

Linear units vs insertion units — two different settings

The first thing to understand is that AutoCAD tracks two separate ideas of 'units', and only one of them governs how blocks scale on insertion.

The first is the linear unit format — whether coordinates read out as decimal, architectural (feet and inches), engineering or fractional. This is purely a display preference; it changes how numbers look in the command line and dimensions, not the real size of anything.

The second is the insertion scale unit (the INSUNITS system variable). This is the one that matters for downloaded blocks. It tells AutoCAD the real-world unit of your drawing — millimetres, metres, inches, feet — so that when a block drawn in one unit is inserted into a drawing set to another, AutoCAD automatically rescales it. Set this to Millimeters for the blocks here and the conversion happens for you.

Open the UNITS dialog and check the settings

Type UNITS (or UN) and press Enter to open the Drawing Units dialog. Two areas matter.

Under 'Length', set the Type and Precision to whatever suits your work — Decimal is the usual choice for metric drafting. This is cosmetic and won't break a block.

Under 'Insertion scale', find the drop-down labelled 'Units to scale inserted content'. This is the critical control. For the millimetre blocks on this site, set it to Millimeters. If you work in a metre-based template, you can leave it at Meters and AutoCAD will still rescale the millimetre block correctly on insertion (a 1700 mm bath comes in as 1.7 m). The key is that the setting is not 'Unitless' — that is what causes blocks to arrive at raw, unconverted size.

Setting units on the command line with INSUNITS

If you prefer the keyboard, you can set the same value directly. Type INSUNITS and press Enter, then enter a code: 0 is Unitless, 1 is Inches, 2 is Feet, 4 is Millimeters, 5 is Centimeters, 6 is Meters.

For the blocks on this site, type INSUNITS, Enter, then 4, Enter. That tells AutoCAD your drawing is in millimetres. There is a companion variable, INSUNITSDEFSOURCE, which sets the assumed unit of a block that has no unit of its own — leaving both pointed at millimetres keeps everything consistent. Setting these on the command line is faster than opening the dialog once you know the codes, and it is easy to script into a template.

Working in metres or in imperial templates

Not everyone draws in millimetres, and the blocks still work — you just need the insertion scale set honestly.

If your template is in metres, set insertion scale to Meters. AutoCAD reads the block's millimetre units, divides by 1000, and a 600 mm cabinet lands as 0.6. Your snaps and dimensions then read in metres as expected.

If you work in a US imperial template (architectural feet and inches), set insertion scale to Inches or Feet to match your template, and AutoCAD will convert the metric block on the way in. A 600 mm appliance becomes roughly 23.6 inches. Because the conversion is automatic, you never type a scale factor — the only job is to make sure the insertion-scale unit reflects what your drawing actually represents.

Bake the units into a template so you set them once

Setting units on every new file is tedious and easy to forget, which is exactly when a block sneaks in at the wrong size. The fix is to set the insertion scale once, then save the file as a drawing template (.dwt).

Open a fresh drawing, run UNITS, set the insertion scale to your standard (Millimeters for most architectural work), set your layer standards and text styles too, then use SAVEAS and choose 'AutoCAD Drawing Template (*.dwt)'. From then on, start new work from that template (NEW, pick your .dwt) and the units are already correct. A firm-wide template means every drafter inserts blocks against the same unit assumption, which quietly eliminates a whole class of scaling errors across a project.

A ten-second pre-insertion checklist

Before you insert any downloaded block, run this quick check and you will rarely be surprised.

- Type UNITS and confirm the insertion scale is set to a real unit, not Unitless. - Confirm it reflects your drawing — Millimeters for a mm template, Meters for a metre template. - Note the block's units (the blocks here are in millimetres; it is stated on every download page). - Insert at scale 1 and check one known dimension against a measured object already in the drawing.

That last step is the safety net: drop the block in, run DIST or MEASUREGEOM across a feature you know the size of, and confirm it reads what you expect. If a 600 mm cabinet measures 600, your units are right and you can carry on; if it reads 0.6 or 600000, your insertion scale and the block's unit are mismatched and the checklist tells you exactly where to look.