In the English language, verst is singular with the normal plural versts. In Russian, the nominative singular is versta, but the form usually used with numbers is genitive plural verst - 10 verst, 25 verst, etc. - whence the English form. "Verst" is sometimes used in Russian colloquial speech as a synonym for a kilometer.
A mezhevaya versta (Russian: ? , literally border verst) is twice as long as a verst.
In Finland, virsta was originally 1.069 km according to the Swedish standard, but the Russian verst of 1.0668 km replaced it after the province was annexed to the Russian Empire in 1809. Virsta was originally 600 sylis (fathoms, 1.781 m), but was then changed to 500 syli, since the Russian syli was longer, 2.134 m. A derived unit was peninkulma = 10 virsta (see Finnish units of measurement). Metrication replaced virsta with the kilometre in the 1880s.