There are calculators online that will give you an answer. The only trouble with them is they are probably wrong. It's a decent place to start but I wouldn't allow yourself to freak out if you go above or below what they tell you. Eating more calories instead of less may make you want to get more exercise which will help more than just sitting under a blanket freezing to death because calories are too low because some dumb calculator told you that's what you need for weight loss.
Female, 5'3", 49, Starting weight: 163lbs. Current weight: 135 (more or less).
Starting squat: 45lbs. Current squat: 157.5 x 2