The BMR is the minimal daily caloric requirement needed to sustain life in a resting individual. If your BMI indicates a need to lose weight you will have to adjust your daily caloric intake to induce your body to use up its fat stores. In order to calculate the amount of calories your body needs to maintain basic body functions use the BMR formula as follows.

For a woman take the weight in kg x 22 or the weight in pounds x 10 to calculate the minimum amount of caloric intake. 
Example 
A women of 66kg would need 66*22=1450 calories a day to maintain basic life functions. A moderately active person needs up to 50% extra calories per day to maintain weight. When restricting calories to lose weight choose the weight you would like to be and calculate its BMR.

For men the formula is, weight in kg x 24 or the weight in pounds x 11.
Example
A moderately active man with a weight of 92 kg and a height of 1.85 m. has a BMI of 26.9. His maximum healthy BMI is 25, which means he should weigh 25*(1.85*1.85)= 85.6 kg or less. To reach this goal he should aim for a daily intake of 85.6*24=2050 calories.