# How to use Buffer Calculations In Tableau 2020.1

> This is content from just-tim, the data-and-analytics channel by Tim Ngwena (formerly 'Tableau Tim'). Tim has 12+ years of hands-on BI experience and covers Tableau most of all, plus Power BI, Looker, Hex, SQL and data modelling, the analytics industry, and the craft of doing the job — always tool-agnostic and honest about the trade-offs.

- **Author:** Tim Ngwena (just-tim, https://just-tim.com/about)
- **Published:** 2020-02-25
- **Format:** Video · 4 min watch · transcript available
- **Topics:** Data visualisation, Analytics
- **Tools:** Tableau (buffer, calculated fields, makepoint, maps)
- **Canonical:** https://just-tim.com/posts/how-to-use-buffer-calculations-in-tableau-2020-1
- **Watch:** https://www.youtu.be/Z5QiATfk47g

I walk through the new buffer function for spatial analysis in Tableau 2020.1, using mock car dealership data with latitude and longitude. I show how to create a spatial point with MAKEPOINT, then draw a radius around it using BUFFER and visualise overlapping coverage areas on a map.

## Key takeaways

- The buffer function in Tableau 2020.1 draws a radius around a spatial point so you can visualise coverage areas on a map
- Latitude and longitude alone aren't a spatial data type, so you first need MAKEPOINT (added in 2019) to create a true spatial point
- BUFFER takes three arguments: a geometry (point, line or polygon), a number for the radius, and the units such as kilometres
- Assigning geographic roles to your latitude and longitude fields before building lets you work with the data straight away
- Adding company name to colour and adjusting opacity makes overlapping radiuses easy to spot for catchment analysis

Watch the full video, read the transcript and use chapter deep-links on the page: https://just-tim.com/posts/how-to-use-buffer-calculations-in-tableau-2020-1

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just-tim — Data and analytics, with a point of view. · https://www.youtube.com/channel/UC7HYxRWmaNlJux-X7rNLZyw · https://twitter.com/TableauTim · https://www.linkedin.com/in/timngwena