What size to sell
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In most categories the pack size is a price-point decision. Here it interacts with how long the product survives once opened, which makes a generous size an active risk.
Size is a shelf-life decision
A product has a period after opening, and the customer's usage rate decides whether they finish it inside that window. Sell a large jar of something with a four to six month life and most customers will still be using it at month eight.
What they experience then is a degraded product with your name on it, and they will not attribute that to the size they bought.
What the categories actually use
Serums cluster around 30 ml, which is roughly two to three months of twice-daily use and happens to fit most actives' stability. Moisturizers sit near 50 ml. Cleansers and body products run larger because they are used generously and are usually simpler formulas with longer lives.
Those conventions exist because they roughly match usage to stability, not because of tradition.
Smaller is safer
A smaller pack is finished sooner, so less of its life is spent open. It also has less headspace in absolute terms, is cheaper to replace if a batch fails, and lets a customer try you without committing.
Against that, packaging is a larger share of unit cost at small sizes and customers read small as expensive per milliliter.
The resolution is to size to the period after opening rather than to the price point, and to let the price follow.
Ranges and trial sizes
One size per product is simplest and is right for most small brands. Every additional size is another packaging minimum, another label, another fill setup and another line of inventory.
A trial size earns its place where the full size is expensive and the product is unfamiliar, which describes most serums. It is also the most useful thing to include in a kit.
What rarely earns its place is a very large size. It lengthens the time the product spends open, and it is a discount on the thing whose freshness you are selling.
The sizes we stock
