Commands

APERTURE command in AutoCAD : Controls the size of the object snap target box

If you need a clear, step-by-step guide to using the APERTURE command in AutoCAD, this article explains what the command does, how to use it, why it may appear to fail, useful alternatives, and practical tips to get consistent snapping behavior.

What the APERTURE command is (Explications)

The APERTURE command in AutoCAD controls the size of the object snap target box (the square that appears around the crosshairs when you hover near an Object snap point). It is a pixel-based setting that affects how easy it is to grab endpoints, midpoints, centers, and other snap points without zooming in.

  • APERTURE affects the snap detection area for object snaps, not the selection box used for selecting objects (that is PICKBOX).
  • The default value varies between AutoCAD versions (commonly around 10–12 pixels), and values are entered as integers (most versions accept values roughly from 1 to 100).
  • Use APERTURE to make snapping faster (larger aperture) or more precise (smaller aperture).
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How to use the APERTURE command — step by step

Method A — Command line (fastest)

  1. Type APERTURE at the command prompt and press Enter.
  2. Type the desired numeric value (for example 12) and press Enter.
  3. Move the cursor near geometry to see the new object snap target box size.

Tip: If you don’t see immediate change, move the cursor or zoom/pan slightly to refresh the display.

Method B — drafting settings dialog

  1. Right-click the Object Snap (OSNAP) button on the status bar and choose Settings…, or type DSETTINGS and press Enter.
  2. In the Drafting Settings dialog, find the Aperture size slider or input box on the Object Snap tab.
  3. Adjust the slider or enter the numeric value and click OK.

Useful shortcuts and related keys

  • Toggle running object snaps: press F3.
  • Quick object snap menu: press Shift + Right-click and choose a snap type.
  • Access Object Snap settings quickly: type OSNAP and press Enter.

Examples and before/after description

  • Before: With an aperture of 3 pixels, the snap target box is very small — you frequently need to zoom in to snap endpoints precisely.
  • After: With an aperture of 15 pixels, the snap target box is larger — snapping is faster and you can pick points from farther away without zooming.

Use a moderate aperture (e.g., 8–20) for general drafting. Increase only if you work on high-resolution monitors or when working with very dense geometry.

Common reasons APERTURE appears not to work (Errors / fixes)

  1. Object snaps are turned off

    • Symptom: The snap target box appears but snapping does not occur.
    • Fix: Press F3 to toggle running object snaps, or enable specific snaps via OSNAP.

  2. Using the wrong setting — PICKBOX vs APERTURE

    • Symptom: Selection box size changes but snapping behavior does not.
    • Fix: Remember APERTURE changes the snap target box; PICKBOX changes the selection box. Adjust the correct variable.

  3. Aperture value out of expected range or UI not updating

    • Symptom: You entered a value but see no visual change.
    • Fix: Enter a different value, move the cursor, or type REGEN or pan/zoom to refresh the display. Use the Drafting Settings dialog to verify.

  4. High-DPI / display scaling issues

    • Symptom: Aperture looks too small or too large on high-resolution monitors.
    • Fix: Increase the numeric value of APERTURE to compensate, or adjust Windows scaling. In some AutoCAD versions, toggling graphics settings (Options > System > Graphics Performance) can help.

  5. Conflicts with object snap overrides or temporary grips

    • Symptom: You expect a certain snap but a different grab happens.
    • Fix: Clear temporary overrides (press Esc), ensure the desired running snap modes are enabled, or explicitly select the snap from the Shift+Right-click menu.

  6. Corrupt profile or settings

    • Symptom: Unexpected behavior despite correct settings.
    • Fix: Reset AutoCAD profile or restore default settings, or test in a New drawing.
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Alternative methods to improve snapping and precision

  • Use object snap tracking (OTRACK) to track alignment paths from snapped points — this reduces the need for a very large aperture.
  • Use OSNAP running modes selectively (Endpoint, Midpoint, Center, Intersection, Perpendicular) instead of relying on aperture size alone.
  • Use Zoom or PAN temporarily to pick tight points when precision is required.
  • Enable Polar tracking and Ortho when drawing orthogonally to reduce snapping errors.
  • Use the Nearest object snap for complex curves when Endpoint or Midpoint is not appropriate.
  • Adjust PICKBOX for selection behavior when you have difficulty selecting small objects.

Practical tips for reliable snapping (Tips)

  • Use a moderate APERTURE value (commonly 8–20) for everyday drafting; increase only on very high-resolution screens.
  • Keep the most used running object snaps enabled (Endpoint, Midpoint, Center, Intersection) and toggle off rarely used ones to reduce accidental snaps.
  • Learn Shift + Right-click to override running snaps quickly — useful when you want one-off snap behavior.
  • If you switch between monitors with different DPI, set up workspace profiles with different APERTURE values.
  • Save a custom profile with your preferred APERTURE, PICKBOX, and OSNAP settings for consistency across projects.

FAQ

What is the difference between APERTURE and PICKBOX?

APERTURE controls the size of the object snap target box used for snapping. PICKBOX controls the size of the selection box used when selecting objects. They affect different behaviors; adjust the one relevant to your problem.

How do I restore APERTURE to the default value?

Type APERTURE at the command line, press Enter, then enter the value you consider default (AutoCAD defaults vary by version — typically around 10–12). Alternatively, reset your AutoCAD profile to restore all defaults.

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Why does changing APERTURE not make snapping easier?

Possible reasons: running object snaps are disabled (F3), the wrong snap modes are on, the screen needs regenerating (use REGEN), or high-DPI scaling changes pixel behavior. Verify running snaps and try a larger aperture value.

Can APERTURE be set differently per drawing or per profile?

APERTURE is a system variable that is stored in your AutoCAD profile. Create separate profiles if you want different aperture settings across projects or monitor environments.

Is a bigger aperture always better?

No. A larger aperture makes snapping faster but can cause accidental snaps to nearby geometry. Use a balance — typically 8–20 pixels, adjusted to your monitor and project density.

How do I quickly toggle object snap without changing APERTURE?

Press F3 to toggle running object snaps on/off. Use Shift + Right-click to access temporary object snap overrides.

Why does the aperture look different on another monitor?

Different displays and Windows DPI scaling change pixel density. Increase the APERTURE numeric value on high-DPI monitors, or create a dedicated profile for that display.

Where else can I change aperture settings besides the command line?

Open Drafting Settings (type DSETTINGS or right-click OSNAP and choose Settings…) and adjust the Aperture size slider on the Object Snap tab.

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