A line weight hierarchy tells the reader what to look at first. Set your scale below and you get a four-tier set in millimetres, with the pixel equivalents for print and for a portfolio PDF. The values step along the ISO 128 series (0.13, 0.18, 0.25, 0.35, 0.50, 0.70, 1.00 mm), which is the progression firms and CAD defaults are built around (the standard itself is ISO 128-2:2020, and ISO 128 covers the wider family of line conventions).
Pick the scale you are drawing at:
1:10 & 1:20 Construction details, wall sections
| Tier | mm | px @300 dpi | px @150 dpi | What it draws |
|---|---|---|---|---|
| Cut | 1.00 | 11.8 | 5.9 | Section cuts, ground line, the edge you slice through |
| Primary | 0.70 | 8.3 | 4.1 | Building outline, walls in plan, main object edges |
| Secondary | 0.50 | 5.9 | 3.0 | Doors, windows, furniture, paving joints, planting |
| Annotation | 0.25 | 3.0 | 1.5 | Dimensions, centrelines, hatching, text, leaders |
1:50 Plans and sections for a single building
| Tier | mm | px @300 dpi | px @150 dpi | What it draws |
|---|---|---|---|---|
| Cut | 0.70 | 8.3 | 4.1 | Section cuts, ground line, the edge you slice through |
| Primary | 0.50 | 5.9 | 3.0 | Building outline, walls in plan, main object edges |
| Secondary | 0.35 | 4.1 | 2.1 | Doors, windows, furniture, paving joints, planting |
| Annotation | 0.18 | 2.1 | 1.1 | Dimensions, centrelines, hatching, text, leaders |
1:100 Standard plan and elevation sheets
| Tier | mm | px @300 dpi | px @150 dpi | What it draws |
|---|---|---|---|---|
| Cut | 0.50 | 5.9 | 3.0 | Section cuts, ground line, the edge you slice through |
| Primary | 0.35 | 4.1 | 2.1 | Building outline, walls in plan, main object edges |
| Secondary | 0.25 | 3.0 | 1.5 | Doors, windows, furniture, paving joints, planting |
| Annotation | 0.13 | 1.5 | 0.8 | Dimensions, centrelines, hatching, text, leaders |
1:200 Large buildings, landscape site plans
| Tier | mm | px @300 dpi | px @150 dpi | What it draws |
|---|---|---|---|---|
| Cut | 0.35 | 4.1 | 2.1 | Section cuts, ground line, the edge you slice through |
| Primary | 0.25 | 3.0 | 1.5 | Building outline, walls in plan, main object edges |
| Secondary | 0.18 | 2.1 | 1.1 | Doors, windows, furniture, paving joints, planting |
| Annotation | 0.13 | 1.5 | 0.8 | Dimensions, centrelines, hatching, text, leaders |
1:500 & 1:1000 Masterplans and urban context
| Tier | mm | px @300 dpi | px @150 dpi | What it draws |
|---|---|---|---|---|
| Cut | 0.25 | 3.0 | 1.5 | Section cuts, ground line, the edge you slice through |
| Primary | 0.18 | 2.1 | 1.1 | Building outline, walls in plan, main object edges |
| Secondary | 0.13 | 1.5 | 0.8 | Doors, windows, furniture, paving joints, planting |
| Annotation | 0.13 | 1.5 | 0.8 | Dimensions, centrelines, hatching, text, leaders |
The principle behind the picker is simple: the set does not change, it shifts. Every time the scale halves, move the whole hierarchy one notch lighter along the ISO series. At 1:50 your cut line is 0.70 mm; at 1:100 that same cut line becomes 0.50 mm. Keep the four tiers, keep the gaps between them, and a plan at any scale reads the same way.
What Each Tier Is For
Four tiers is the working minimum and it is enough for almost every drawing in a portfolio. Cut is anything the section plane slices through, plus the ground line. Primary is the object outline that is not cut. Secondary is everything inside it: doors, windows, furniture, paving joints, planting. Annotation is dimensions, centrelines, hatching and text, and it should always be the lightest thing on the sheet. For the full catalogue of line types that sit alongside these weights — dashed, chain, phantom — First In Architecture’s reference is a good companion.
The most common mistake is not using the wrong numbers, it is using too few tiers. A drawing where everything sits at 0.25 mm reads as grey mush at any size. A drawing with a genuine 0.70 / 0.35 / 0.18 spread reads instantly, even as a thumbnail on a reviewer’s second monitor.
ISO 128 Line Weights in mm, Pixels and Points
Use this table when you are converting between a CAD pen set, an Illustrator stroke and an exported PDF. Print work is normally set at 300 dpi; a portfolio PDF sized for screen reading is usually exported at 150 dpi, which halves every pixel value.
| ISO 128 weight (mm) | px @300 dpi (print) | px @150 dpi (portfolio PDF) | pt |
|---|---|---|---|
| 0.13 | 1.5 | 0.8 | 0.37 |
| 0.18 | 2.1 | 1.1 | 0.51 |
| 0.25 | 3.0 | 1.5 | 0.71 |
| 0.35 | 4.1 | 2.1 | 0.99 |
| 0.50 | 5.9 | 3.0 | 1.42 |
| 0.70 | 8.3 | 4.1 | 1.98 |
| 1.00 | 11.8 | 5.9 | 2.83 |
| 1.40 | 16.5 | 8.3 | 3.97 |
| 2.00 | 23.6 | 11.8 | 5.67 |
How to Set Line Weights in AutoCAD
AutoCAD applies line weights at plot time through a plot style table, so the fix belongs in the CTB file rather than in the drawing. Open Plot, then edit the plot style table attached to the layout. Assign each colour a millimetre value from your chosen set, so colour 1 plots at 0.70 mm, colour 2 at 0.35 mm and so on. Draw by colour, plot by pen. You can then re-point a whole sheet set at a lighter CTB when the scale changes, instead of touching any geometry.
If you work in named plot styles rather than colour-dependent ones, the same logic applies per style. Either way, turn the Show/Hide Lineweight toggle on while you check the drawing, because model space shows every line at one pixel by default and hides the problem you are trying to fix.
How to Set Line Weights in Revit
Revit uses sixteen numbered line weights, and each number is given a different millimetre value per view scale. Go to Manage > Additional Settings > Line Weights, and you will see a grid of numbers down the side and scales across the top. This grid is exactly the shift described above, already built into the software: number 5 can be 0.50 mm at 1:50 and 0.35 mm at 1:100 if you set it that way.
Fill the grid with the values from the picker once, at the start of a project, and every view inherits the right weight when you change its scale. Object styles then reference the numbers rather than the millimetres, so you never have to reassign anything view by view.
Line Weights for a Portfolio PDF
A portfolio is read on screen, at roughly half the size of a printed sheet, and often scrolled quickly. That changes two things. First, export at 150 dpi rather than 300: it keeps the file under the 10 MB limit most firm inboxes and grad school portals enforce, and the pixel column above tells you what your weights become. Second, protect the lightest tier. Anything under 0.13 mm can disappear entirely once a PDF is downsampled, so if your annotation layer vanishes in the export, raise it rather than accepting the loss.
Check the result the way a reviewer will see it: open the exported PDF at page-fit on a laptop screen, not zoomed in on your drawing monitor. If the hierarchy still reads at that size, it will survive anywhere. If it does not, widen the gap between tiers before you touch anything else.
Line weights are one part of how a drawing set is judged. For the wider picture, see our guides to portfolio size, format and orientation and to architecture portfolio layout. Weak line hierarchy is one of the recurring faults in our round-up of architecture portfolio mistakes, and it shows up again when you adapt a portfolio template that was drawn at a different scale. The rest of our free utilities live on the free tools page.