A katha (also spelled cottah) is a unit of area in Bangladesh and India approximately equal to 1/20 of a bigha (720 ft² or 66.89 m²).
A katha is approximately 720-square-foot (67 m2) in West Bengal. It is still in use in much of Bangladesh and India But this varries from place to place. You cannot convert Kattha into square feet unless you know how much square feet actually they call as on kattha. In Indian state of Bihar, one kattha may varry from 750 sqft to 2000 sqft.
"Katha". Sizes, grades, units, scales, calendars, chronologies. http://www.sizes.com/units/katha.htm. Retrieved 2007-02-19.