Measure

Every ZIP code or postcode within a radius

find_postcodes_in_radius

Every US ZIP code, or UK postcode sector or district, within a radius of a place, nearest first.

Read-onlyKeeps a shareable map

Use it when

✓ Service areas, delivery zones and direct-mail lists
✓ "Which ZIP codes are within 25 miles of 10001?"
✓ Ad targeting by postcode

Not for

→ Which of YOUR records are within a radius: filter_by_location

Coverage: US (Census ZIP code areas) and the UK (postcode sectors and districts).

Sources

US Census 2024 ZCTA gazetteer: ZIP code centres (2024)
UK postcode district and sector centres (ONS-derived open postcode data) (2026-08-01)
InstaMaps address index (OpenStreetMap, OpenAddresses) and postcodes.io (2026-10-08)

Basis: straight-line distance between centres

Inputs

center

string · required

A ZIP ("10001"), a UK postcode, sector or district ("SW1A 1AA", "SW1A 1", "SW1A"), an address, or "lat,lng".

radius

number · required

Up to 500 miles or 800 km.

unit

string

— One of: mi · kmDefault: "mi"

granularity

string

UK only: postcode sectors ("SW1A 1") or districts ("SW1A"). One of: sector · districtDefault: "sector"

country

string

Optional: worked out from the centre. One of: us · gb

limit

number

Most areas to list, nearest first (up to 2,500); the total found is always given. Default: 500

render

boolean

—

title

string

—

The full description, as the server gives it to an agent

Every US ZIP code, or every UK postcode sector (or district), whose centre is within a radius of a place, nearest first with the distance. The centre can be a ZIP, a UK postcode, sector or district, an address, or "lat,lng". For service areas, delivery zones, direct-mail and ad targeting lists. Straight-line distance between centres (an area counts when its centre is inside). Free: our own copy of the Census ZIP centres and the UK postcode centres. The answer has a run_id: write it into a sheet or map it (render_map from_run). For "who on MY list is within X miles", use filter_by_location instead. Set render to true only when the user wants to keep or share the map: it returns a link, GeoJSON and KML, and update_map can change it later.

A real answer

Captured from the live server on 2026-10-13, trimmed to the first rows.

Request

{
  "center": "10001",
  "radius": 1,
  "limit": 5
}

The answer's first line

9 ZIP codes within 1 mi of 10001 (nearest 5 listed; raise limit for more)

The answer (trimmed)

{
  "center": {
    "input": "10001",
    "label": "10001",
    "lat": 40.7506,
    "lng": -73.9973,
    "country": "US",
    "confidence": {
      "level": "high",
      "score": 0.9,
      "basis": "postcode_as_given",
      "why": "the centre of 10001"
    }
  },
  "radius": 1,
  "unit": "mi",
  "kind": "ZIP code",
  "summary": {
    "found": 9,
    "records": 5,
    "more": 4
  },
  "records": [
    {
      "id": "10001",
      "postcode": "10001",
      "distance_mi": 0,
      "lat": 40.7506,
      "lng": -73.9973
    },
    {
      "id": "10199",
      "postcode": "10199",
      "distance_mi": 0.1,
      "lat": 40.7514,
      "lng": -73.9972
    },
    {
      "id": "10119",
      "postcode": "10119",
      "distance_mi": 0.2,
      "lat": 40.7506,
      "lng": -73.9927
    },
    "… 2 more"
  ],
  "basis": "straight-line distance from the centre to each ZIP code's centre; an area counts when its centre is inside the circle",
  "sources": [
    {
      "name": "US Census 2024 ZCTA gazetteer: ZIP code centres",
      "as_of": "2024"
    }
  ],
  "run": {
    "tool": "find_postcodes_in_radius",
    "at": "2026-10-13T15:59:33.713Z",
    "rows": 5,
    "sources": [
      {
        "name": "US Census 2024 ZCTA gazetteer: ZIP code centres",
        "as_of": "2024"
      }
    ],
    "basis": "straight-line distance between centres",
    "run_id": "run_837d6de48cb8e6b6"
  }
}

Use it in Claude

Add the connector https://get-instamaps.com/mcp and ask in plain words. 5,000 tool calls a day per person, reset at midnight UTC; a call counts once however many rows it carries; a sheet by reference is one call; checking a job is free.

How to add it →