The calculated distance (air line) between Nay Pyi Taw and Thayetmyo is approximately 68 miles respectively 110 kilometers.
By car or train, the actual journey to Thayetmyo is certainly longer, as only the direct route (as the crow flies) between Nay Pyi Taw and Thayetmyo has been calculated here.
Air line (approximately)
110 kilometers
59 nautical miles