Since there are about 24 calories in 1 1/2 teaspoons of sugar and 150 calories in a cup of whole milk, a cup of tea with 1 1/2 teaspoons of sugar and added milk contains about 43 calories. This assumes that one adds about 1/8 cup of milk to the tea.
This number can be lowered considerably by using milk with less fat content than whole milk. For example, a splash of skim milk contains about 11 calories. Of course, tea that contains less milk also contains fewer calories, and tea that contains more milk contains more calories. For this reason, it is always important to measure food out precisely when calorie intake is a concern.