CIRCLE

Draw a precise circle by centre and radius.

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Learning objective

By the end of this lesson you can run the CIRCLE command and draw a circle of an exact radius around a chosen centre point.

What CIRCLE is

CIRCLE creates a single circular object. By default it asks for a centre point first, then a radius. Several alternative options exist (2-point, 3-point, tan-tan-radius) but the centre-radius flow is the foundation.

Why and when you use it

Use CIRCLE for holes, wheels, fasteners, decorative arcs, and anywhere your design needs a closed round shape.

Where to find it in the AutoCAD interface

Ribbon: Home tab → Draw panel → Circle dropdown → 'Center, Radius'.
Menu: Draw menu → Circle → Center, Radius.
Command line: Type CIRCLE and press Enter.
Alias / shortcut: C (then Enter).

Key vocabulary

Centre point: The exact middle of the circle, equidistant from every point on the curve.
Radius: The distance from the centre to the edge.
Diameter: The distance across the circle through the centre. Diameter = 2 × radius.
Quadrant: One of the four cardinal points on a circle (0°, 90°, 180°, 270°). OSNAP can snap to these.

Before you start

Open a new drawing from acad.dwt.
Confirm OSNAP is on (F3) so you can snap the centre to an existing point if needed.
Decide whether you want to specify a radius or a diameter — the lesson uses radius.

Step-by-step instructions

1
Start the CIRCLE command
2
Click the centre point
3
Type the radius
4
Confirm the size with a quick check

Visual reference

Common mistakes & fixes

Typing the diameter when AutoCAD is asking for the radius.
Fix: Either halve your value or, at the radius prompt, type D first, press Enter, then type the diameter.
Picking a centre point with OSNAP off and getting a slightly misaligned circle.
Fix: Press F3 to enable OSNAP, then snap to an existing endpoint, midpoint or intersection.
Clicking instead of typing the radius and getting a random size.
Fix: Always type a numeric radius — never trust the eyeball for engineering geometry.

Troubleshooting

The circle is huge or microscopic.Show

Cause: Your drawing zoom level made the typed radius look unexpected.

Fix: Run ZOOM EXTENTS (Z → E) to refit the view.

AutoCAD asks for a diameter, not a radius.Show

Cause: The last CIRCLE invocation switched the default to Diameter.

Fix: At the prompt type R and press Enter to switch back to radius.

Pressing Enter draws another circle.Show

Cause: Enter on a clean prompt repeats the last command.

Fix: Press Esc to clear, then start the next command deliberately.

Practice exercise

Concentric circles

Draw a circle of radius 50 at any point.
Run CIRCLE again. At the centre prompt, snap to the centre of the first circle (OSNAP → Center).
Type radius 30 and press Enter.
Repeat for radius 10.

Success looks like: You see three perfectly concentric circles (10, 30, 50). LIST any one to confirm its radius.

Pro tips & related commands

Pro tips

At the radius prompt, type D and Enter to switch into Diameter mode for that one circle.
Inside CIRCLE, type 2P to draw a circle through two points (the two clicks become a diameter).
Use the Ttr option to draw a circle tangent to two existing objects with a given radius.

Related commands

ARC(A)
Draw a portion of a circle.
ELLIPSE(EL)
Draw an oval defined by two axes.
DONUT(DO)
Draw a filled ring (two concentric circles).

Lesson quiz

0/3 correct

Score at least 3/3 to unlock lesson completion.

1. After CIRCLE, what does AutoCAD ask for first?

2. At the radius prompt, how do you switch to typing a diameter instead?

3. Which option draws a circle through two clicks that form a diameter?

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