Each person requires a different number of calories per day. The number of calories varies depending on the person's gender, size and level of activity. The number of calories should be reduced if a person is trying to lose weight or increased if trying to gain weight. With a few calculations, you can determine how many calories you need in a day.

### Things You'll Need

- Scale

- Calculator

### Step 1

Weigh yourself without your clothes when you wake up in the morning. This is the most accurate way to assess your current weight.

### Step 2

Multiply your body weight by 10 if you are an adult. For example, if you weigh 150 pounds, the figure would be 1500.

### Step 3

Add your body weight to the total if you are a woman. For example, a 130 pound woman would add 1500 + 130. The result is 1630 calories per day. This formula works for average sized women weighing between 100 and 160 pounds.

### Step 4

Add twice your body weight to the total if you are a man. For example, a 170 pound man would add 1500 + 340. The result is 1840 calories per day. This formula works for average sized men weighing between 130 and 220 pounds.

### Step 5

Calculate your daily calorie intake differently if you are trying to lose a little weight or do not get much exercise. Instead of using the other formula, multiply body weight by 10. For example, a 150 pound person should consume 150 x 10 = 1500 calories per day. This formula works for both men and women.

### Step 6

Consult a doctor if you are trying to lose 20 pounds or more. A doctor could recommend a diet with as few as 1200 calories per day regardless of current body weight. However, only do this under the advice and supervision of a doctor.

### Step 7

Increase your daily calorie intake if you are a very active person, a fit athlete or trying to gain wait. People who exercise at least one hour a day at least five days per week fit into this category. A simple way to calculate an increased calorie diet is to multiply body weight by 20. For example, an active 150 pound adult could consume 150 x 20 = 3000 calories per day. This formula works for both men and women. Individuals need to watch their weight to determine whether increasing calories to this level causes weight gain.