How to draw a cylinder in perspective

If you want it as a course

4 stages, each one taking a support away

Optional, and it changes nothing about how the measurement works — a stage decides which supports are on the sheet and nothing else. You move on when the measurement says you have it rather than after a fixed number of drawings, and skipping ahead or stepping back is always available. Leave it and the page is just a page with a drill on it.

1. 01

   Built with you

   The axis, then each end, then the sides — every mark checked before the next.

   clears when you finish the build

2. 02

   Axis on the page

   Eye level and the centre line are there. Both ends and both sides are yours, and the bottom end still has to open up.

   clears on 2 attempts at 78 or better

3. 03

   Eye level only

   You place the centre line yourself. Everything the two rules are measured against is now something you decided.

   clears on 2 attempts at 78 or better

4. 04

   Nothing given

   An empty sheet, at whatever angle you like. This is the drill as it has always been, and by now it should feel different.

   clears on 3 attempts at 80 or better

5. ✓

   When you have got it

   Both ends inside four degrees of square, with the far end at least a few degrees more open than the near one, on a cylinder you drew at an angle you did not choose in advance.

Start at stage 1 · Built with youtakes you to the instrument and builds one with you

What it can name

The faults, drawn

A percentage on its own tells you nothing you did not already know. These are the separable problems the measurement identifies — each with a different fix, which is the whole reason for telling them apart. Every example below is a real stroke, generated by the same code that tests the engine.

• Ends off square

  The one this exercise exists for. The short way across an end ellipse runs along the axis of the form — not upright, not square to the page. An ellipse drawn on its own always looks fine, which is why this survives until the form is finished and then reads as bent.

• Far end drawn narrower

  The instinct, and it is backwards. The far end is smaller on the page, so it feels as though it should be squashed too. Its degree opens as it recedes; drawn the other way it describes a cone.

• Both ends the same degree

  The second ellipse copied from the first rather than drawn for where it sits. Without a shift between them there is no depth in the form and it reads as a flat tube.

• Sides that miss the ends

  Drawn between the ellipses rather than onto them. A silhouette line leaves the widest point of one end and arrives at the widest point of the other, and those points are not where the eye first looks.

• No taper

  Sides run as parallel rails, which is what a cylinder looks like flat on the page and never what one looks like in space. Anything going away from you gets narrower.

• Bowed silhouette

  Drawn from the wrist, or drawn slowly enough to steer. The silhouette of a cylinder is straight, and a confident line that misses beats a careful one that wanders.

How the number is made

What the score actually measures

Weighted toward squareness and recession, because those are the two things that make a drawn cylinder read as a solid — the rest describe how tidily it was assembled. Every threshold, and the evidence behind it.

Which end is near, and which end is far

On a cylinder the end FURTHER from your eye is the rounder of the two and the smaller one across — those two travel in opposite directions as it recedes, and reversing them is the commonest error in the exercise. Looking down at a can on a table, the far end is the bottom; looking up at one, it is the top. Both ends are ellipses whose short way across lies along the axis of the form, at whatever angle the form is drawn.

This is the confusion worth clearing up before anything else, because the words used for it are genuinely ambiguous. On an upright cylinder seen from above — a tin can on a table below your eye level — the TOP end is the one nearer your eye, and the BOTTOM end is the one further away. So the bottom is the rounder of the two ellipses, and the slightly smaller one across. If you are looking up at the cylinder instead, it is the other way round.

"Near" and "far" mean distance from your eye. "Top" and "bottom" mean position on the form. They line up differently depending on where you are standing, which is exactly why saying "the far end is rounder" is correct and saying "the bottom end is rounder" is only correct sometimes. Everything you read on this page names the actual end — top or bottom — and tells you which of them is the far one for the view you have set, rather than leaving you to work it out.

The far end gets rounder, not flatter

This is the one people get backwards, and it is worth being blunt about why. The far end of a cylinder is smaller on the page — everybody knows that, and it is true. The instinct that follows is that it should shrink in every sense, so the ellipse gets squashed as well as narrowed.

Two different things are being measured and it is worth keeping their words apart, because most of the confusion here is vocabulary rather than geometry. HOW WIDE ACROSS an end is means the long way over the ellipse, its size on the page — and the far end is smaller across, by about a tenth on a normal cylinder. HOW OPEN it is means the short way over the ellipse against the long way, which is an angle rather than a size. Those two travel in opposite directions as the end recedes, which is the entire point, so this page never calls an end "wider": it is smaller across, and it is more open.

In fact it OPENS UP as it goes away from you. Draughtsmen call this the ellipse’s degree, and it is just an angle: a circle seen square on is 90°, one seen edge-on is 0°, and every ellipse in between is somewhere on that scale. Carry the cylinder on far enough and its ends keep opening until one becomes a full circle. That is the direction they travel, and a cylinder whose two ends sit at the same angle has no depth in it at all.

Exaggerate it at first. In several thousand years of people drawing cylinders, almost nobody has overdone this one.

Why the ends are the hard part

A cylinder is two ellipses and two lines, which sounds like the easiest form there is. It is not, and the reason is that an ellipse drawn on its own always looks fine. Nothing about it is wrong until it is attached to a form, and then the whole thing reads as bent without anybody being able to say which part is at fault.

The rule is that the short way across each end ellipse — its minor axis — runs along the axis of the cylinder. Not upright, not square to the page: along the axis, wherever the axis happens to point. The moment the form is drawn at an angle, the ellipse everybody instinctively draws is the one that is square to the page, and it is wrong by exactly the angle the cylinder is tilted at.

It is a single number, it is exact arithmetic, and it is invisible from the inside. That combination is the entire argument for measuring it rather than squinting at it.

What this has to do with boxes

The box drill asks whether your straight edges agree about where they are going. This asks the same question of your curves, and it is the exercise that follows boxes in every curriculum that teaches boxes at all — Drawabox puts 250 cylinders directly after its 250 boxes for exactly this reason.

The two are the same skill seen from opposite sides. A box is easy to check with a ruler and hard to draw; a cylinder is easy to draw and, until now, almost impossible to check, because the thing that is wrong with it is an angle between an ellipse and a line that nobody has drawn.

Two ways to use this page, and why the ends move together

LEARN IT builds the cylinder with you in four marks: the centre line first, then the top end, then the bottom end, then the two sides. Each one is checked as you draw it — an ellipse against how much of the outline you actually travelled, whether you closed it, and where you put it; a straight mark against its aim, length and straightness — and a mark that misses is removed with the reason named. Before any of that you move the eye level and the distance yourself, and the point of doing so is what you see while you do it: BOTH ends change at once, and they change by different amounts.

That is the rule the whole exercise turns on, and it is the one thing a static diagram cannot show you. An end ellipse gets more open the further it is from your eye level, and smaller across at the same time. The two ends of one cylinder are at different distances from your eye by definition, so they are never the same ellipse — the far one is always the rounder of the two, and by how much depends on where you are standing. Drag the eye level slider and watch the top and bottom degree readings move apart and together. Nobody has to tell you the rule afterwards.

MEASURE IT gives you an empty sheet and grades what you draw: how many degrees off square each end sits relative to the axis of the form, and whether the far end opens up as it recedes. The four-stage course puts the two in order — the guided build, then the form with only its skeleton shown, then eye level alone, then nothing at all.

Questions