Ensure you use the right calculator. There is one for Males and one for Females.
Above is your Basal Metabolic Rate. You now need to account for your daily activity using the calculator below.
Now you have your Total Daily Calories. This needs adjusting for your goal. It's really simple. If you want to stay the same weight keep the number above the same. If you want to lose weight, subtract 300 from this number. If you want to put increase weight add 300.
*DISCLAIMER* Every single one of these calorie calculators is an estimate. Regardless of what anyone tells you.
As Phil Learney quoted 'To think we can control or put a formula on a living organism and have a solid assurance of its response and outcome would be absurd.'
Use these numbers, be consistent, and adjust where necessary. If you need any help, I will always happily answer any questions or queries.