How to Estimate the Population Within a Service Area

Estimate population within a service area

You have a travel-time or travel-distance service area and need an estimate of how many people live inside it. Ask the Isoline API to enrich each returned feature with population data instead of combining a separate raster dataset yourself.

Task flow: origin + reachability limits + details=population → service-area polygons with population estimates.

This is useful for early market analysis, facility comparison, accessibility studies, and emergency planning. Treat the result as a dataset-derived estimate rather than a current census count or a forecast of customers.

Request population details

Add details=population to an Isoline API request. This example returns population estimates for three cumulative drive-time areas around central Berlin.

https://api.geoapify.com/v1/isoline?lat=52.52&lon=13.405&type=time&mode=drive&range=300,600,900&traffic=free_flow&details=population&format=geojson&apiKey=YOUR_API_KEY

Reduced response: Polygon coordinates and unrelated properties are omitted. Population values come from a live response and can change when the source dataset or service calculation changes.

{
  "type": "FeatureCollection",
  "features": [
    {
      "properties": {
        "range": 300,
        "details": {
          "population": {
            "value": 142866,
            "attribution": {
              "sourcename": "GHS-POP R2019A",
              "attribution": "© European Union, 1995-2021",
              "license": "Creative Commons Attribution 4.0 International (CC BY 4.0)",
              "url": "http://creativecommons.org/licenses/by/4.0/"
            }
          }
        }
      }
    },
    {
      "properties": {
        "range": 600,
        "details": { "population": { "value": 624675 } }
      }
    },
    {
      "properties": {
        "range": 900,
        "details": { "population": { "value": 1448324 } }
      }
    }
  ]
}

Read the estimate from feature.properties.details.population.value. Preserve the accompanying attribution when presenting or exporting the result.

Interpret cumulative population estimates

Each value belongs to the complete area within that feature's time limit. Do not add 142,866 + 624,675 + 1,448,324: the three polygons overlap because every larger area contains the smaller reachable bands.

For the example response:

Subtract adjacent cumulative values only when the ranges share the same origin and calculation settings. For multiple facilities, their service areas can overlap; merge the polygons first and estimate population for the combined geometry with an appropriate population dataset instead of summing facility-level estimates.

Also keep the calculation inputs with stored results. A changed travel mode, traffic model, avoidance rule, or range changes both the polygon and its population estimate.