The calculated distance (air line) between Starokostyantyniv and Zhytomyr is approximately 74 miles respectively 119 kilometers.
By car or train, the actual journey to Zhytomyr is certainly longer, as only the direct route (as the crow flies) between Starokostyantyniv and Zhytomyr has been calculated here.
Air line (approximately)
119 kilometers
64 nautical miles