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Buffer vs Clip vs Intersect

Goal: Pick the right tool, every time. Side-by-side comparison with examples.

→ Pair this with Geoprocessing Tools (roadmap).

At a glance

Tool Purpose Inputs Output
Buffer Make a zone around features One layer + distance Polygons (zones)
Clip Crop a layer to a boundary Input layer + clip layer Input geometry inside boundary, input attributes only
Intersect Find overlap and combine attributes Two or more layers Overlap geometry, all input attributes

Visual

INPUTS:           A (red, target)        B (blue, boundary)
                  ┌──────────┐           ┌────────┐
                  │ ▭ ▭ ▭ ▭  │      +    │        │
                  │ ▭ ▭ ▭ ▭  │           │        │
                  │ ▭ ▭ ▭ ▭  │           └────────┘
                  └──────────┘

BUFFER:    around B by 50 units      → ┌──────────┐ enlarged

CLIP:      A clipped by B           →  ▭ ▭         (inside B only,
                                                    A's attributes)

INTERSECT: A ∩ B                     → ▭ ▭         (overlap only,
                                                    A's + B's attributes)

Buffer

"I want a zone around something."

Input Distance Output
Schools (points) 500 m Polygons around each school
Streams (lines) 30 m Polygons either side of streams
Parcels (polygons) 10 m Larger polygons around each parcel

When to use: any "within X distance" question.

→ Tool detail: Buffers

Clip

"I want to keep only the part inside this boundary, with the original attributes."

Input Clip layer Output
US streets Fulton County Streets inside Fulton, with their original attributes
Sentinel-2 image Watershed Image cropped to the watershed
Parcels Floodplain Just the parcel pieces inside the floodplain — but no flood-zone attributes

When to use: cropping data to a study area.

→ Tool detail: Clip

Intersect

"I want only the overlap, and I want both layers' attributes."

Inputs Output
Parcels + Floodplain Parcel pieces inside the floodplain — plus the flood zone code on each
Streets + Floodplain Street segments inside the floodplain — plus flood zone code
Zoning + Land Cover Where each zoning category overlaps each land cover, both attributes preserved

When to use: tagging features with the polygon they overlap, and you need to keep info from both.

→ Tool detail: Intersect

Decision tree

flowchart TD
    Q{Your question}
    Q -->|"Within X distance"| B[Buffer]
    Q -->|"Crop to a study area"| C[Clip]
    Q -->|"Overlap of two layers"| W{Need both<br/>layers' attributes?}
    W -->|Yes| I[Intersect]
    W -->|No, just geometry| C2[Clip]

    classDef q fill:#fef3c7,stroke:#f59e0b,color:#92400e
    class Q,W q
    classDef ans fill:#dcfce7,stroke:#10b981,color:#065f46
    class B,C,I,C2 ans

A combined example

"Find all parcels within 1 km of a school, inside Fulton County, and tag them with the school name and flood zone."

  1. Buffer schools by 1 km.
  2. Clip parcels to Fulton County (don't need attributes from Fulton).
  3. Intersect the clipped parcels with the school buffer (carry the school name) and with the floodplain (carry the flood zone code).

That's the entire workflow in three tools.

Practice

Try all three

  1. Pick a city. Get streets, hospitals, and city boundary.
  2. Buffer hospitals by 0.25 mi.
  3. Clip streets to the city boundary.
  4. Intersect the clipped streets with the hospital buffer.
  5. The output is the length of street within walking distance of a hospital. Calculate total length.