Lot’s of people throw out the figure that the front line is 1,200 kilometers long. Not really. The length of the border of Ukraine (pre-2014) with Russia is 1,974 kilometers (1,227 miles). This is the land border. The length of the border with Belarus (which I do not think is going to re-enter this contest) is 891 kilometers (554 miles). The entire coastline of Ukraine is 3,783 kilometers (2,351 miles). I think this last figure includes Crimea.
(courtesy of @War_Mapper, map dated 18 May 2024)
But, they really are not fighting from Chernihiv to Sumy and have not done so since April 2022. This is a large portion of that 1,200 kilometer figure. They do share a border with Russia so Ukraine obviously has to protect these areas, but there really has not been any fighting in these areas for over two years. We do not expect that will change.
Second, they really cannot do major operations along the Dnipro River from Kherson up to the Kakhovka Reservoir. There was, in the best of times only three bridges across this river, and I gather that number is three less now. This creates supply issues and with all the drones, missiles and air support, hard to see how this is corrected. No one has yet to do any major military operations across the Kakhovka Reservoir. This takes a significant chunk of miles off any active front.
Therefore, for all practical purposes the front runs from the western border of Kharkiv province over to Kupyansk, down through the Donbas and then through Zaporizhzhia Oblast to the Kakhovka Reservoir. This is about 800 kilometers, vice 1,200.
Slightly more precise measurement using Google Earth:
Distance along Kharkiv Oblast border (To Kupyansk): 225 kilometers
From Kupyansk to Bakhmut: 124 kilometers
From Bakhmut to Vuhledar: 107 kilometers
From Vuhledar to Reservoir: 144 kilometers
Total = 600 kilometers
Multiply by 1.25 (a little figure borrowed from Napoleon): 750
If it was measured more precisely the front might be a little longer.
One kilometer is 0.62 miles. Therefore an active front of roughly 800 kilometers or roughly 500 miles.
Then factor in troop numbers and varying troop density and we have a rather historical “Eastern Front” style conflict.