How to Find a Timezone from Latitude and Longitude

Why coordinates need a timezone lookup

Latitude and longitude identify a position, but they do not say what the local clock should read. A timezone lookup maps the position to a named timezone that carries its full daylight-saving history.

1. Call the timezone API

Send lat and lon. Both parameters are required.

curl -H "X-API-Key: YOUR_MAPSI_API_KEY" \
  "https://mapsi.dev/v1/timezone?lat=51.5033635&lon=-0.1276248"

const response = await fetch(
  "https://mapsi.dev/v1/timezone?lat=51.5033635&lon=-0.1276248",
  { headers: { "X-API-Key": "YOUR_MAPSI_API_KEY" } }
);

const data = await response.json();

console.log(data.timezone); // "Europe/London"

import requests

response = requests.get(
    "https://mapsi.dev/v1/timezone",
    params={"lat": 51.5033635, "lon": -0.1276248},
    headers={"X-API-Key": "YOUR_MAPSI_API_KEY"},
)

data = response.json()
print(data)

{
  "success": true,
  "coordinates": {
    "lat": 51.5033635,
    "lon": -0.1276248
  },
  "timezone": "Europe/London",
  "utc_offset": "+00:00",
  "dst": true,
  "current_time": "Monday, September 28, 2026 at 5:11:56 PM GMT+1"
}

2. Use the IANA timezone name

Use the timezone value with any timezone-aware date library. Do not try to work it out from longitude: real boundaries follow borders and political decisions, not longitude lines. The response also includes utc_offset and a dst flag for the moment of the request.

const timezone = data.timezone;
// "Europe/London"

new Date().toLocaleString("en-GB", { timeZone: timezone });

3. Build local-time features

Store timestamps in UTC and keep the IANA name alongside them. With that you can show local times, schedule notifications at a sensible local hour, group events by local date and convert UTC values into the user's local time. Store the name rather than the offset, because offsets change with daylight saving.