A Yojana (Sanskrit : योजन ) is a Vedic measure of distance that was used in ancient India. It is equivalent to about 13 km (8 mi) for terrestrial use and 6400 km for cosmological distances as per modern measures of distance, although the exact value is disputed among scholars (between 8 and 13 km (5 and 8 mi))
In modern Hindi the word yojanaa (Hindi : योजना) means "plan" or blueprint, and is etymologically connected with the Cartesian notion of distance in the word yojana. However, note that the words "yojana'" and "yojanaa" are different, and pronounced differently. The last sound of the second word is pronounced "aa" as in arm [ārm].
Variations on length
The length of the yojana varies depending on the different standards adopted by different Indian astronomers. In the Surya Siddhanta of the 5th century, for example, a yojana was equivalent to 8.0 km (5 mi), and the same was true for Aryabhata's Aryabhatiya (499). However, by the time of Paramesvara in the 14th century, the yojana was defined to be about 1.5 times larger than it was in Aryabhata's time, thus being equivalent to about 13 km (8 mi).
Religious leader A. C. Bhaktivedanta Swami Prabhupada gives the equivalent length of a yojana as 13 km (8 mi)  throughout his translations of the Bhagavata Purana. Some traditional Indian scholars give measurements between 13 km and 16 km (8–10 miles) or thereabouts. Alexander Cunningham, in The Ancient Geography of India, takes a yojana to mean 13 km (8 mi).
The Thai equivalent โยชน์ (pronounced "yot") gives the distance as 16km. The word is also used to describe a large distance, the same way an English speaker would say something is "miles" away. 
The height of the mythical mountain Meru Parvat is estimated to be 1,00,000 yojan in Jain cosmology where 1 yojan is given as 6,400 km (4,000 mi) – approximately the radius of the Earth. If the length of a Yojana is taken to be approximately 13 to 16 km (8 to 10 mi), like it was in later times, then its subsidiary measurements are as follows:
- 1 angula = 16 to 21 mm
- 4 angulas = one dhanu graha (bow grip) = 62 to 83 mm
- 8 angulas = one dhanu musti (fist with thumb raised) = 125 to 167 mm
- 12 angulas = 1 vitasti (handspan: distance between tip of thumb and tip of last finger when palm is stretched) = 188 to 250 mm
- 2 vitastis = 1 aratni (cubit) = 375 to 500 mm
- 4 aratnis = 1 danda = 1.5 to 2.0 m
- 2 dandas = 1 dhanu = 3 to 4 m
- 5 dhanus = 1 rajju = 15 to 20 m
- 2 rajjus = 1 paridesha = 30 to 40 m
- 100 parideshas = 1 krosha (or gorata) = 3 to 4 km
- 4 kroshas = 1 yojana = 13 to 16 km
- 1,000 yojanas = 1 Mahayojan = 13 to 16 Mm
- Richard Thompson (1997), Planetary Diameters in the Surya-Siddhanta, Journal of Scientific Exploration 11 (2): 193–200 
- O'Connor, John J.; Robertson, Edmund F., "Aryabhata I", MacTutor History of Mathematics archive, University of St Andrews.
- Srimad Bhagavatam 10.57.18 (translation) "one yojana measures about eight miles"
- one Bengal mile=one coss= 2000 yards=1.8288 kilometres