A handy tip for determining subject size?

[Cyclops]

I was photographing this dead fly and tought, hmmm, an observer will have no idea of how small it is and I had no tools for measuring it. But i knew that the original image before cropping was taken with the macro lens set to 1:1 so basically what the sensor sees is the objects true size! So then I had to look up my sensor size and simply added the dimensions as text borders in the image. Then I can save that, and upload that image thus:



Then I go back to the image and crop if necessary to get a closer view.