Calories in 3 glasses

From a table row to one glass

1. Read the per-100 g row for mango lassi out of the Indian Food Composition Tables 2017 — analysed on Indian samples, so Indian wheat and Indian milk are not swapped for American ones. It gives 89 kcal and 2.1 g protein per 100 g.
2. Weigh what is actually served. This site enters 1 glass at 250 g (curd, mango pulp and sugar). That weight is the number other calorie sites decline to state, and it is where their answers stop being answers.
3. Multiply, linearly, and print the working: 89 × 250 ÷ 100 = 223 kcal per glass. Nothing is rounded up, adjusted or smoothed — two glasses are exactly twice one.
4. Reconcile the energy against its own macronutrients with Atwater factors on every build. A row more than 15% away from 4P + 4C + 9F (20% above 6 g of fibre) stops the build rather than shipping.

per glass   =  per 100 g  ×  serving grams ÷ 100
Mango Lassi        =     89 kcal ×  250 g ÷ 100  =  223 kcal
energy check       =  4P + 4C + 9F  ±15%  (±20% if fibre ≥ 6 g)

The full method, and where it is weakest →