Calculating your perfect calorie intake per day is a very common request. Unfortunately, there is a large margin of error. The only truly accurate way to measure calorie needs are with direct or indirect calorimetry, both of which aren't readily available to the general public.
When estimating caloric needs, there are many, many factors to consider. Fortunately, there's a pretty simple way to get a rough idea! If you track your food intake for a few days in an app like MyFitnessPal (assuming you continue to eat as you normally do, without any dramatic differences), it should tell you how many calories you consume per day. If you have been maintaining your weight at that daily caloric intake, then that intake is (more or less) your caloric maintenance.
From your caloric maintenance level, you'll need to restrict some calories to lose weight. About a 500-1,000 calorie deficit is appropriate for a healthy 1-2 pound weight loss per week. Just make small changes and continue to monitor your weight. If your maintenance calories are already low, avoid dropping them too much, because you still need enough calories, protein, and other nutrients to stay healthy. Your exercise also contributes to your calorie balance. The more you exercise and the more active you generally are throughout the day, the more calories your body will use. If you use more calories in your day, that allows you to eat more in your diet, and still be in the deficit for weight loss.