I'd like to select features with circles having precise radius in QGIS. By default this tool is freehand so it is hard to get a precise value.
Not sure if there's a direct approach to this but there are alternative methods:
Fast, less precise
Use the Measure Line tool from the toolbar to draw a radius as precise as you can (remember to right-click to stop drawing the line):
Then use the Select Features by Radius tool to draw the circle from each point of the measured line:
Slow, more precise
Create a point layer and add a point. Use the Buffer tool (Vector > Geoprocessing Tools > Buffer(s) to create a polygon of the point (maximise the "Segments to approximate" and set your buffer distance to what you want the radius to be, becareful as this is dependent on your CRS).
Then use one of the Select by location tools (either from the Processing Toolbox or from Vector > Research Tools > Select by location), select both layers and check the intersect option:
*Updated answer to this question
There is now a new plugin called "Select by radius plus" tool which can be downloaded from the plugins menu in QGIS.
The user interface is as follows:
The user can select from either meters, kilometers or miles and also has the option to use centroid as the selection parameter.
The plugin was created by Lutra Consulting https://www.lutraconsulting.co.uk/, and the code repository can be found here: https://github.com/lutraconsulting/qgis-select-by-radius-plus-plugin