Private cooks have different rates. The pay depends on experience, employer, and the place. Take note that there are some cooks who may get paid less. But with a certification, enough experience, and the right employer, the salary will be higher.
Most cooks in the U.S. and countries like Australia can charge between $25 and $50 per hour. A lot of cooks prefer to charge hourly since this is the most effective way to price their services. There are some private cooks who charge per serving. The going rate for this is between $10 and $18 per serving.