QGIS – Buffer by Percentage

By David Crowther

Did You know…. There is a Plugin for QGIS that allows you to buffer an object by a percentage value – it’s called Buffer by Percentage!

To install the plugin, choose Plugins > Manage and Install Plugins > search for the Buffer by Percentage tool and install.

The new tool will be available in the Processing Toolbox.

In this example, we have a Planning Apps layer with a polygon representing a circular area…

We would like to increase the polygon objects area by a given percentage….. making the circle larger.

To do this….

1 - Select the planning app object from the map and it turns yellow.

2 – Then from the Processing Toolbox > Buffer by Percentage > choose the Fixed Percentage Buffer Plugin.

3 – In the Fixed Percentage Buffer tool choose the settings:

• Input Layer > Planning Apps
• Selected features only – Tick
• Percentage - 150%
• Segments – 50 – this defines how smooth the resultant buffer object is

4 – Press Run and a buffer layer is created which increases the size of the original feature by 150%.

Note - if you chose a value smaller than 100% you will decrease the size of the original object – shrinking it!

If you wish to increase the size of your features by a variable value, you can use the Variable Percentage Buffer tool and define the % value per record using a field in your dataset.