First-angle vs third-angle projection – view layout and symbol

What it shows

Engineering drawings use two arrangements of views, both defined in ISO 5456-2. In first-angle projection, common in Europe and much of the world, the object lies between the viewer and the projection plane, so the top view goes below the front view and the view from the left goes on the right. In third-angle projection, used in the USA and Canada, the plane lies between viewer and object like a glass box, so the top view goes above and the right view on the right. The six views themselves are identical; only their positions change, and the truncated-cone symbol tells which method a drawing uses.

How to use

Choose a Part and the Number of views, then press First angle and Third angle in turn and watch the views slide to new places as the symbol changes. Turn on 3D and drag Unfold the projection planes or press Open / fold to see why the layouts differ. Press View quiz: choose the right view, pick the drawing that belongs in the ? position and read why each wrong answer is wrong.

Parameters you can change

• Part Stepped block with a hole, L-bracket with a sloped rib, U-block with offset holes, Chamfered block with a hole
• Starting projection method First angle (Europe), Third angle (USA)
• Number of views Three views, Six views
• Draw hidden edges (dashed)
• Start with the view quiz

Questions to explore

1. In first-angle projection, why is the view from the left drawn on the right of the front view?
2. How can you tell from the truncated-cone symbol which projection method a drawing uses?
3. An edge is dashed in the view from the left. How does it appear in the view from the right?