You can use a measuring tape/ruler (in inches preferably).
Lay a cord, string or chain on a table and extend it from one end to the other.
Use the measuring tape/ruler to determine the length. If the measurement isn’t a precise number, you may round it up.
Using a measuring tape, wrap a piece of string around your hand below the wrist bone.
Depending on whether you like it snug or loose, adjust the measuring tape accordingly to determine the desired length.
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