1 - use calipers as the OP has done. 2 - use a strip of paper wrapped around and divide by pi. (rizla) 3 - read the measurement off the old seatpost.
If you don't already have a post that fits it gets a bit trickier..
@provenrad started
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1 - use calipers as the OP has done.
2 - use a strip of paper wrapped around and divide by pi. (rizla)
3 - read the measurement off the old seatpost.
If you don't already have a post that fits it gets a bit trickier..