Amp-hour is the measure of an electric charge. For Example if you have a battery with a capacity of 10 Ah then the battery can supply a current of 10A continuously for 1 hour.
Kilo-watt hour is a unit used to measure electrical energy. So we need voltage to calculate it.
Formula for Ah to Kwh conversion is simple, multiply the Ah and the Voltage of the battery which will give you the answer in watts, divide by 1000 further to get the answer in Kilo-watt hour.
kWh = (Ah × V) ÷ 1,000