Bigha (Kaccha / Gujarat) to Guntha (Gunta): the quick answer
To convert bigha (kaccha / Gujarat) to guntha (gunta), multiply the value by 16. To go the other way, multiply guntha (gunta) by 0.0625 to get bigha (kaccha / Gujarat).
↔ Convert guntha (gunta) to bigha (kaccha / Gujarat) instead