Why does my perspective drawing look stretched and distorted?

The construction is probably right. The distortion comes from vanishing points placed too close together, which is the drawing equivalent of standing 30 centimetres from a building.

Difficulty: intermediate
Time: 25 min
Read: 5 min

Short answer

Move the vanishing points much further apart — usually well off the edge of the paper — and keep everything you draw within a cone of about 60 degrees from the centre of view. Objects drawn out at the edges of a wide construction stretch, and that stretch is geometrically correct and still looks wrong.

Do this first

How do I draw in perspective?

Perspective construction produces exactly what a camera produces, including the parts of what a camera produces that we find unacceptable. A very wide angle of view stretches the corners; that is true of a lens and it is true of a ruled drawing. The fix is not better geometry, it is a narrower angle of view.

Step by step

Find the centre of vision.It is the point on the horizon line directly in front of you — where a line from your eye meets the picture at right angles. Everything else in the drawing is judged relative to it.
Draw the cone of vision and stay inside it.Draw a circle centred on the centre of vision. Anything comfortably inside it looks natural; anything outside starts to stretch. As a working rule the circle's diameter is roughly the distance from the centre of vision to the nearer vanishing point, and objects at the very edge will look wrong however carefully you construct them.
Push the vanishing points apart.The distance between them is what sets the apparent focal length. Close together means a wide-angle, dramatic, distorted look. Far apart means a longer lens, a calmer and more natural image. If a box looks like a wedge of cheese, the points are too close.
Work on a bigger surface than the drawing.Tape your sheet to a larger board or a lining paper offcut and mark the vanishing points on the board. Almost all believable two-point construction has at least one point off the page.
Check the near corner angle of any box.The vertical corner nearest you divides the two visible faces. The two top edges running away from it should make an angle greater than about 90 degrees between them. If it is much less, the box is being viewed at an impossible angle and will read as crushed.
Do not force every object onto the same vanishing points.Only objects sharing the same orientation share vanishing points. A rug turned at an angle to the room, or a chair pushed round, has its own pair of points on the same horizon. Forcing everything onto two points is a common cause of a room that feels subtly wrong.
Keep the verticals truly vertical unless you are in three-point.In two-point construction, a vertical that leans is simply an error, and it is very visible. Check them against the edge of the paper.
Test the result by turning it upside down or looking at it in a mirror.Perspective errors survive scrutiny because you know what the object is meant to look like. Reversing the image removes that knowledge and the wrongness leaps out.

Tips

If you are constructing from a photograph, the photograph already has a focal length baked into it, and matching it is a matter of extending the edges in the photo to find where the vanishing points actually fall.
Circles suffer worse than boxes at the edge of a wide view — a wheel constructed near the edge of the cone becomes visibly egg-shaped. Keep round things near the centre of vision.
A drawing that has to fit a lot in is usually better solved by stepping back in imagination and drawing it smaller than by widening the angle of view.
Comic and concept artists distort deliberately for drama. Knowing the cone of vision is what lets you break it on purpose rather than by accident.

Common mistakes

Putting both vanishing points on the paper because it is convenient — On an A3 sheet that gives an angle of view no lens would offer, and the stretch appears in everything you draw. Convenience is the single most common cause of this fault.
Drawing the whole scene, then adding perspective lines to check it — Construction has to come first. Fixing an established drawing by ruling lines to a point produces a hybrid that satisfies neither observation nor geometry.
Assuming the distortion means the maths is wrong — The construction is doing exactly what it should. The problem is the viewpoint you have specified, and the only fix is to change it.

If it doesn't work

Boxes near the edges look like wedges

Cause: They sit outside the cone of vision — Fix: Move them towards the centre of the composition, or move both vanishing points much further apart and redraw.

A room interior looks like a fish tank seen through a bulge

Cause: One-point construction with the vanishing point far off centre, or a very wide angle — Fix: Bring the vanishing point closer to the centre of the wall you are facing and reduce how much of the room you are trying to show.

Furniture in a room all points slightly wrong

Cause: Everything forced onto the room's two vanishing points — Fix: Give each differently-angled object its own pair of points on the same horizon line.

The building leans

Cause: Verticals not vertical in a two-point construction — Fix: Rule them against the paper edge. If you actually want convergence, commit to a proper three-point construction with a distant third point.

Questions people ask

How far apart should the vanishing points be?

There is no single number, but as a starting point, further apart than the width of your paper. The wider the gap, the longer the apparent lens and the calmer the image.

Why do my photographs look distorted at the edges too?

Same cause. A phone's main camera is fairly wide, and the ultra-wide is wider still. Faces and circles near the frame edge stretch. Step back and zoom rather than moving closer.

Is the cone of vision exactly 60 degrees?

It is a convention rather than a physical constant — people quote anywhere from 45 to 60. Treat it as a warning zone rather than a boundary, and judge the result by eye.