The calculated distance (air line) between Ma‘arratmişrīn and Manbij is approximately 80 miles respectively 129 kilometers.
By car or train, the actual journey to Manbij is certainly longer, as only the direct route (as the crow flies) between Ma‘arratmişrīn and Manbij has been calculated here.
Air line (approximately)
129 kilometers
69 nautical miles