Grab a well-fitting shirt from your closet, neatly place it flat on an even surface and measure from armpit to armpit. Look your measurement up in the tables and you have your size.
Wrap a narrow strip of paper around the correct finger so it's comfortable. Draw a line across both strips and measure the distance between the lines. A little help from someone may be useful.
The image below is indicative only. Want to know for sure which length you need? Tie a string around your neck. Carefully.
No flexible tape measure? Wrap a narrow strip of paper around your wrist so it's
comfortable. Draw a line across both strips and measure the distance
between the lines. A little help from someone may be useful. Check above at 'Rings' for an example.
All imperial measurements are directly calculated from the metric measurements, That's why they seem so random and not nicely rounded off. Stupid imperial measurements.