GPR is not the ideal tool to calculate the rebar size. There is a technique where you can get approximate values for the rebar size by measuring...

GPR is not the ideal tool to calculate the rebar size. There is a technique where you can get approximate values for the rebar size by measuring the depth to the rebar from both in line and cross line data and the difference will give an approximate diameter. There are more accurate and easier instruments to detect the rebar size and cover such as the Profometer PM8000 which can be used in combination with GPR for a holistic approach to your concrete investigations.