There isn't a fixed number. It's your daily protein target, minus what your meals already supply, divided by the protein in one scoop.
Estimates are for general guidance only and are not medical advice. For a personalised plan, book a free guided tour at RPM Gym.
The headline is scoops a day, as a range, because the target is a range. The low end takes you to the bottom of the evidence-based range for your goal and the high end to the top. Anywhere between is reasonable, so pick the end that suits your appetite and your budget.
The target isn't worked out here. It comes from the same shared model the protein calculator uses, so both pages give the same daily range for the same weight and goal. This page does the second half only: what's left after food, and what that is in scoops.
The row worth reading twice is the share of your target coming from powder. If a third or more of your day is out of a tub, the arithmetic is still right. The fix that also feeds you, though, is usually another portion of protein at a meal.
Tub duration uses the scoop's powder weight, not its protein. The tool divides the tub's servings by your scoops a day at the middle of your range, which is the honest single figure for something you'll actually drink.
Daily target = bodyweight × 1.4–2.0 g/kg (maintain) = bodyweight × 1.6–2.2 g/kg (build muscle, or lose fat) Gap = target − protein from food (never below 0) Scoops a day = gap ÷ protein per scoop Share from powder = gap ÷ target Servings in the tub = tub weight ÷ scoop weight Tub lasts = servings ÷ scoops a day, at the middle of the range
An 80 kg man building muscle, eating about 90 g of protein a day from meals, with a 2 kg tub whose 30 g scoop gives 24 g of protein.
Between 1.6 and 3.6 scoops, and at the top of that range nearly half his protein would come out of a tub. Two scoops puts him comfortably inside the range. The bigger lever is food: another 30–40 g at meals brings the middle of the range down to between one and one and a half scoops, and roughly doubles how long the tub lasts.
As many as it takes to close the gap between your meals and your daily target, and no more. The tool works it out from your weight, your goal and what you already eat. For some people that's one or two scoops; for people who already eat plenty of protein, it's none.
The scoop count isn't the thing to watch; your total protein is. Two 24 g scoops add about 48 g. If that keeps your day inside the target range for your goal, the number of scoops matters very little. If you have a kidney condition or have been told to limit protein, follow that advice rather than any range here.
Whatever the nutrition panel says for one serving. The scoop's weight is a different number and always larger, because the powder carries more than protein. Put the protein figure, not the scoop weight, into the calculator.
Divide the tub by the scoop weight to get servings, then by your scoops a day. A 2 kg tub with a 30 g scoop holds about 67 servings: roughly 33 days at two scoops a day, or 67 days at one.
Goal changes the target, so it changes the answer. In a deficit and while building muscle the shared model uses 1.6–2.2 g per kg of bodyweight; for maintenance it uses 1.4–2.0. Same food, same tub, a different number of scoops.
If that's when it suits you, fine, but timing is the smaller lever. The ISSN position stands put total daily protein ahead of timing, so a shake you reliably have at breakfast does more than one you sometimes forget after a session.
If you'd like someone to look at what you eat and how you train before you buy the next tub, the free guided tour at RPM Gym in Al Manhal is a sensible first stop.