An indication of an ambient temperature near food is received using an ambient temperature sensor of a food thermometer, and an indication of a food temperature at an interior portion of the food is received using one or more thermal sensors of the food thermometer. A rate at which the indication of the food temperature changes is determined, and the completion time is estimated based on at least the indication of the ambient temperature near the food and the rate at which the indication of the food temperature changes. In one aspect, a resting temperature rise is estimated based on the rate at which the indication of the food temperature changes and at least one of a food type, a thickness of the food, and an amount of time for the indication of the food temperature to increase by a temperature rise value during a period of cooking.