How to Use the Boolean Modifier in Blender

The Boolean modifier is how you cut holes, merge shapes, and carve intersections out of meshes without touching a single vertex by hand. It's the backbone of hard-surface modeling—think bolt holes, panel cuts, and combining primitives into complex forms. This guide starts with a simple cut you can follow in two minutes, then goes deeper into solvers, clean topology, and the gotchas that trip people up. Everything here is tested in Blender 4.5 LTS.

Quick version: add a Boolean modifier to your main object, set the operation to Difference, point it at a second "cutter" object that overlaps it, and hide the cutter. Blender subtracts the cutter's volume in real time, and nothing is destroyed until you apply.

What you'll need

Blender 4.5 LTS (any 4.5.x build). Earlier 4.x versions work too, with one naming difference noted below.
Two mesh objects that overlap in 3D space—your main object and a "cutter." The default cube plus an added cylinder is perfect for practice.
No add-ons required. If you want a base mesh to practice on instead of primitives, any model works, including one from the A23D 3D model library.

Difficulty: Beginner to intermediate Time to complete: 10–15 minutes

Cut your first hole: a step-by-step walkthrough

We'll drill a cylindrical hole through the default cube. One action per step.

Open Blender to the default scene. You should see the Cube already selected.
Add a cutter object. Go to Add > Mesh > Cylinder (or press Shift+A and choose Mesh > Cylinder). A new cylinder appears at the 3D cursor.
Move and scale the cylinder so it passes through the cube. Press S, type 0.4, and press Enter to shrink it, then press G to grab and position it so it clearly overlaps the cube's volume. The two meshes must intersect for a Boolean to do anything.
You should now see the cylinder poking through the cube.
Select the Cube (the object you want to cut into), not the cylinder. This matters—the modifier goes on the object you're keeping.
In the Properties editor on the right, click the Modifier Properties tab (the blue wrench icon).
Click Add Modifier > Generate > Boolean. The Boolean modifier appears in the stack.
Set Operation to Difference (it's the default). This subtracts the cutter from the cube.
Click the Object field (the eyedropper/object picker) and choose Cylinder from the list.
Nothing looks different yet—that's expected, because the cylinder is still sitting inside the cube, hiding the cut.
Select the Cylinder and press H to hide it in the viewport.
You should now see a clean cylindrical hole punched through the cube. The cut is live: unhide the cylinder (Alt+H), move it, and the hole follows.

Tip: Booleans stay non-destructive until you apply them. You can reposition the cutter, change the operation, or delete the modifier anytime. Keep your cutters organized in their own collection so your outliner doesn't turn into a mess.

When you're happy with the result and want to "bake" it into real geometry, hover your cursor over the Boolean modifier and press Ctrl+A, or click the modifier's dropdown (v) menu > Apply.

The hole is now permanent geometry, and the modifier is gone from the stack.

Watch out: Applying is one-way. Once you apply, you can't drag the cutter to reshape the hole anymore. Save a copy or keep the cutter object around if you might revise it later.

The three Boolean operations

Every Boolean comes down to one of three operations, set in the Operation dropdown:

Difference — cuts the cutter's volume out of your main mesh. This is the one you'll use most: holes, notches, carved detail.
Union — merges the cutter into your main mesh and removes the interior faces, giving you one continuous surface. Good for welding separate shapes into a single form.
Intersect — keeps only the volume where both meshes overlap and discards everything else. Handy for trimming a shape to a boundary or creating a shared cross-section.

Tip: If a Difference looks inverted—Blender keeps the overlap instead of removing it—check that your cutter's normals are facing outward. In Edit Mode, select all (A) and use Mesh > Normals > Recalculate Outside (Shift+N). Flipped normals are the single most common cause of weird Boolean results.

Choosing a solver: Float, Exact, or Manifold

The Solver dropdown controls the algorithm Blender uses, and it's the difference between a clean cut and a broken mesh. Blender 4.5 gives you three:

Float — a simple, fast solver with good performance, but it doesn't handle overlapping (coplanar) geometry well. Fine for quick, clean cuts on simple shapes.
Exact — a slower but far more reliable solver with full support for overlapping geometry. This is the safe default when a cut misbehaves.
Manifold — usually the fastest solver, but it only works correctly on manifold (watertight, no holes or loose edges) meshes, plus the special case of a Difference with a plane.

Watch out — version difference: In Blender 4.0–4.4, the solver options are named Fast and Exact, and there's no Manifold option. "Float" is the 4.5 rename of the old "Fast" solver. If you're on an older build, read "Float" as "Fast" throughout this guide. (Verify the exact labels in your version.)

A practical rule of thumb: start with Exact if you care about a correct result and your meshes are messy or overlapping. Switch to Float or Manifold only when Exact is too slow on heavy geometry and your meshes are clean.

Advanced options that actually matter

Expand Solver Options under the modifier for the fine controls. Which ones appear depends on the solver you picked.

Overlap Threshold (Float solver) sets the maximum distance between two faces before Blender treats them as overlapping. If a Float Boolean leaves gaps or artifacts along a seam, nudge this value up slightly. If that doesn't fix it, switch to Exact—the threshold is a workaround for a limitation the Exact solver doesn't have.

Self Intersection (Exact solver) tells Blender to correctly handle meshes that intersect themselves, not just each other. It costs performance, so leave it off unless your cutter or main mesh has self-overlapping geometry and the result comes out wrong.

Hole Tolerant (Exact solver) optimizes the output for non-manifold geometry—meshes with holes or loose edges. It's slower, so the manual's advice is to enable it only when the Exact solver actually shows errors on non-manifold meshes, not as a default.

Materials (Exact solver) controls how materials land on the newly created faces:

Index Based maps the source mesh's first material slot to your main mesh's first slot, second to second, and so on.
Transfer copies the cutter's actual materials over, adding new material slots to your main mesh as needed.

This is worth setting deliberately when your cutter and main object have different materials—for example, if you're carving a panel and want the cut faces to take a specific material. Once your model is cut and slotted, this is also where clean PBR materials pay off, since the Boolean respects your material assignments instead of scrambling them.

For the full option reference, the official Blender Boolean modifier documentation is the authoritative source.

Getting clean results

Booleans are only as good as the meshes you feed them. A few habits keep the output tidy:

Apply scale before booleaning. Select your objects and press Ctrl+A > Scale. Non-uniform or unapplied scale is a frequent cause of bad cuts.
Keep cutters simple and manifold. A clean, closed cutter produces a clean cut. High-poly or broken cutters produce n-gons and stray edges.
Expect n-gons at the seam. Booleans create n-gons where surfaces meet. That's fine for static hard-surface props, but if you plan to subdivide or deform the result, you'll need to add supporting edge loops and clean up the topology afterward.
Use a collection for cutters. Set your cutter objects' Object Properties > Viewport Display > Display As to Wire or Bounds so they don't obscure your model, and park them in a dedicated collection you can toggle off.

Tip: For a one-off cut you don't need to keep live, you can skip the modifier entirely and use the Edit Mode tool at Face > Intersect (Boolean). See the Intersect (Boolean) documentation for that workflow.

Troubleshooting

The cut doesn't appear / nothing happens. The two meshes probably don't overlap, or you assigned the wrong object in the Object field. Confirm the cutter physically intersects the main mesh and that you picked the cutter, not the main object.

The result is inverted (Blender keeps the wrong part). Your cutter's normals are likely flipped. Enter Edit Mode on the cutter, select all (A), and run Shift+N to recalculate normals outside.

The Boolean looks glitchy, with black patches or missing faces. You're probably on the Float solver with overlapping geometry. Switch Solver to Exact. If it's still wrong on a messy mesh, enable Self Intersection.

Applying the modifier tanks performance or crashes on heavy meshes. Exact is expensive on dense geometry. Reduce the cutter's poly count, or if both meshes are clean and watertight, try the Manifold solver for a big speed-up.

Wrap-up

You can now cut, merge, and intersect meshes non-destructively, pick the right solver for the job, and clean up the results. The natural next step is combining Booleans with other modifiers—stack a Bevel after your Boolean to soften the hard cut edges, or drop the finished model into a scene and texture it. If you're pulling assets into Blender to model against, the A23D Blender plugin handles one-click import with PBR materials already wired up.