Acres to Bigha (Kaccha / Gujarat): the quick answer
1 ac = 2.5 bigha-k
1 acre equals 2.5 bigha (kaccha / Gujarat)
To convert acres to bigha (kaccha / Gujarat), multiply the value by 2.5. To go the other way, multiply bigha (kaccha / Gujarat) by 0.4 to get acres.