Sports nutrition calculators can help with estimating a healthy weight (body mass index). The calculators can also give you an idea of your total daily energy needs, including your resting calories needs (bare minimum calories in a day for survival...too few for good health), and calories burned in various activities. Be sure to read the directions carefully as you use the calculators, especially when you are asked to estimate your daily activity. Many of us are active all day, but not necessarily vigorously active for 20 hours.
Also, be careful how you use the results of the calculators. They are a starting point to set goals, not an exact measurement. Have fun!