LazyTools

🔒 Every tool runs in your browser, the files and values you enter are never uploaded to any server. How it works

📍 Google Polyline Encoder / Decoder

Decode a Google Maps polyline string into coordinates (and GeoJSON), or encode a list of lat/lng points into one, with precision 5 or 6.

3 points (lat, lng)

38.5, -120.2
40.7, -120.95
43.252, -126.453

GeoJSON LineString

{
  "type": "LineString",
  "coordinates": [
    [
      -120.2,
      38.5
    ],
    [
      -120.95,
      40.7
    ],
    [
      -126.453,
      43.252
    ]
  ]
}

Encode a list of latitude/longitude points into a Google-encoded polyline string, or decode one back into coordinates (and GeoJSON). It's the compact format the Google Maps Directions API returns for routes. Remember polyline order is latitude, longitude, the reverse of GeoJSON's. Use precision 6 for the higher-precision variant some services use. Everything runs in your browser. 🔒
Rate this tool:
Anonymous, no account, no identifier

How the google polyline encoder / decoder works

Google's Encoded Polyline Algorithm squeezes a list of latitude/longitude points into a short ASCII string, the compact form the Google Maps Directions API returns for a route. Each point is stored as the difference from the previous one, scaled by 10^precision (5 by default), zig-zag encoded to handle negatives, and split into base-32 chunks written as printable characters. This tool implements that algorithm exactly, both ways: paste an encoded string to decode it into coordinates and a GeoJSON LineString, or paste a list of "lat, lng" points to encode them. Choose precision 6 for the higher-precision variant some services (and OSRM/Valhalla) use.

One thing to watch: a polyline stores coordinates in latitude, longitude order, the opposite of GeoJSON, which uses longitude, latitude. This tool keeps that straight, showing decoded points as lat/lng and emitting correctly-ordered GeoJSON. Precision must match how the string was created, decoding a precision-6 polyline as precision 5 puts the points in the wrong place, so if a route looks off by a factor of ten, switch the precision. Everything is computed on your device; no coordinates are uploaded.

Frequently asked questions

What is a Google encoded polyline?

A compact ASCII string that represents a series of latitude/longitude points, defined by Google's Encoded Polyline Algorithm. It's what the Google Maps Directions API returns for a route's path, and it's widely supported by mapping libraries because it's much shorter than a list of raw coordinates.

How do I decode a polyline to coordinates?

Paste the encoded string into the decoder and it outputs the list of latitude/longitude points, plus a GeoJSON LineString you can drop into a map. Make sure the precision matches how it was encoded (5 for Google's default).

What is the difference between precision 5 and 6?

Precision is how many decimal places of latitude/longitude are preserved: precision 5 (Google's default) keeps about 1-metre resolution, precision 6 keeps about 10 cm and is used by some routing engines like OSRM and Valhalla. The two aren't interchangeable, decode with the same precision the string was encoded at.

Why are my decoded points in the wrong place?

Usually a precision mismatch (try switching between 5 and 6), or a latitude/longitude order mix-up. Polylines are latitude-first; GeoJSON and many map APIs are longitude-first. This tool labels the order to avoid the confusion.

Does it output GeoJSON?

Yes, decoding produces a GeoJSON LineString with the coordinates correctly reordered to longitude, latitude, ready to paste into Leaflet, Mapbox or any GeoJSON tool.

Are my coordinates uploaded?

No, encoding and decoding run entirely in your browser and nothing is transmitted, so location data stays on your device. It works offline too.

Related file converters

From the blog