Every bottle carries three volume numbers, and only one is the number on your label. Nominal capacity is the volume you intend to fill. Brimful capacity is the volume to the top of the neck. Overflow capacity is the volume before it spills. Confusing them produces a 500 ml pack that cannot hold 500 ml.
Quick answer
- Nominal capacity is the labelled fill volume; brimful and overflow are the physical limits of the container.
- A filled bottle needs headspace. Filling to the brim leaves no room for thermal expansion or capping.
- Under EU Directive 76/211/EEC, actual content must average at least the nominal quantity, and no single pack may fall below twice the tolerable negative error.
What exactly is nominal capacity?
Nominal capacity — abbreviated “nom.” or “NC” — is the volume of product the pack is designed to contain. It is the number you fill to, the number printed on your artwork, and the number a regulator holds you to. It is a commercial and legal quantity, not a physical measurement of the container.
Nominal capacity is usually a round market size: 30 ml, 50 ml, 100 ml, 200 ml, 500 ml, 1 L. Designers choose it from what the shelf already sells, not from what the bottle physically holds. That gap is where most filling-line problems come from. Three related numbers belong next to it on any quotation:
| Term | What it is | Who cares about it | Typical writing |
|---|---|---|---|
| Nominal capacity (NC) | The intended fill volume, and the declared quantity on pack | Regulators, your filler line, your artwork | 500 ml |
| Brimful capacity (BC) | Volume to the top edge of the neck finish, filled and allowed to settle | Structural designers, capping engineers | 520–540 ml |
| Overflow capacity (OC) | Volume at which the container overflows through the neck | Anyone doing volumetric filling trials or dosing maths | 520–540 ml |
| Usable / fill volume | What the filler is set to deliver in practice | Production, QA, your 3PL | 500 ml ± stated tolerance |
| Headspace | Brimful capacity minus nominal capacity | Formulation, capping, logistics | Expressed as ml or as a percentage |
Headspace on a standard cosmetic bottle is normally 5–10% of brimful capacity, and more for products that expand, foam or are filled warm. Specify it as a number, because the filling line is set against it.
What is the difference between brimful capacity and overflow capacity?
They are two ways of measuring the same upper limit, and on a moulded bottle they are effectively the same number. The difference is the method, and where the limit actually sits.
| Brimful capacity | Overflow capacity | |
|---|---|---|
| Definition | Volume when filled to the brim, i.e. the top edge of the neck finish | Volume at which the liquid reaches the highest point of the neck and spills |
| How it is measured | Decant or gravity-fill to the top edge, then measure the collected volume | Fill slowly through the neck until overflow begins, measure what passed through |
| Where the limit is | Set by the neck finish geometry | Set by the highest internal point, which may be the neck bore |
| What it tells you | How much the pack physically holds | How much you must not put in it |
| Typical gap to nominal | 5–10% above nominal on a standard cosmetic bottle | Equal to brimful in practice |
The practical consequence: nominal capacity is always lower than brimful and overflow, and the space between them is your headspace. If a supplier quotes only “capacity 500 ml” without saying which of the three they mean, the specification is incomplete and the filler line will be set from the wrong number.
Why can a 500 ml bottle not legally hold 500 ml of liquid?
It can hold 500 ml of liquid. What it cannot do is declare 500 ml and then, on average, deliver less. Nominal capacity is a claim about the pack, and the claim is regulated — in the EU by Directive 76/211/EEC and in the US by 21 CFR 101.105. Both are labelling rules, and both are enforced on the finished pack, not on the bottle.
| Nominal quantity (ml) | Tolerable negative error as % of nominal | Read as |
|---|---|---|
| 5 to 50 | 9% | A 50 ml pack may individually be as low as 45.5 ml |
| 50 to 100 | 4.5% | A 100 ml pack may individually be as low as 95.5 ml |
| 100 to 200 | 4.5% | A 200 ml pack may individually be as low as 191 ml |
| 200 to 300 | 9% | A 300 ml pack may individually be as low as 273 ml |
| 300 to 500 | 3% | A 500 ml pack may individually be as low as 485 ml |
| 500 to 1,000 | 1.5% | A 750 ml pack may individually be as low as about 738.75 ml |
| 1,000 to 10,000 | 1.5% | A 1 L pack may individually be as low as about 985 ml |
Three conditions sit on top of that table under EU rules. Actual contents must average at least the nominal quantity across the batch. Only a limited proportion of packs may sit below nominal. And no pack carrying the ℮ mark may fall below twice the tolerable negative error. Volume is also assessed at 20 °C, whichever unit it is declared in.
In the US, 21 CFR 101.105 requires the net quantity of contents to accurately reveal what is in the container, with reasonable variations from good manufacturing practice recognised; fluid quantities are declared in US fluid ounces with the metric equivalent, and the declaration sits in the lower 30% of the principal display panel. Our article on which test reports export bottles need covers the documents that sit behind these declarations.
Where do capacity tolerance and filling-line fit come in?
Nominal capacity is not a single-point value. Bottle capacity varies across a mould, resin density and wall thickness move it slightly, and the filling line itself has a repeatability band. Every quote should carry a tolerance on both, because “500 ml” without one is not a specification a factory can be judged against.
| Quantity | Who sets it | Typical expression | Why it matters |
|---|---|---|---|
| Bottle nominal capacity | Bottle factory, from mould and measurement | 500 ml ±1% | Defines what the pack can be declared as |
| Brimful / overflow capacity | Bottle factory | 520–540 ml, stated as a range | Sets the physical ceiling and the available headspace |
| Fill volume tolerance | Your filler line | ±0.5% to ±1% of target | Determines whether the batch average clears nominal |
| Dosing closure output | Pump or cap supplier, per stroke | e.g. 4 cc per stroke | Must be consistent enough that the declared volume is real |
| Net weight declaration | Your formula’s density | Stated separately from volume | Solids and pastes are declared by weight, not volume |
Line fit is the other half. A bottle can have correct capacity and still be wrong for your equipment if the neck finish, the base radius or the shoulder shape does not suit the filler. Our guide to bottle capacity and fill volume works through the sizing arithmetic, and the leak, drop and capacity checks behind every bottle covers what is measured before a run is released.
How do you write “capacity” unambiguously in a specification?
Never write the single word “capacity”. Write all three numbers, and state which one the filling line is set against. Send this as the capacity block in your enquiry:
- Nominal capacity, in ml, as the figure you intend to put on the artwork.
- Brimful capacity, in ml, with its measurement method if you need it tight.
- Overflow capacity, in ml, or a statement that it equals brimful.
- Headspace, either as a ml figure or as a percentage of brimful capacity.
- Capacity tolerance on the bottle, stated as a percentage with a plus/minus.
- Fill tolerance your line is capable of holding, so the factory knows which band matters.
- Measurement temperature, because volume is temperature-dependent and the rules of the market assume 20 °C.
- Empty bottle weight, which drives both freight cost and pallet arithmetic and belongs in the same block.
- Neck finish and closure, since the closure decides the usable volume above the shoulder.
- A declaration of what goes on pack, so the bottle’s nominal capacity and your label’s net quantity are visibly the same decision.
If a supplier cannot fill in items 1 to 4, the quotation is missing the numbers that decide whether the bottle can be filled at all.
Which three capacity mistakes cause returns and line stoppages?
1. Ordering a “500 ml” bottle for a 500 ml product, without checking brimful capacity. This is the most common capacity error there is. A 500 ml nominal pack typically has a brimful capacity in the low 500s, so filling to the nominal target leaves only the headspace — which is correct. But if the supplier quoted 500 ml as the brimful figure, the pack is 20–40 ml short of its own label from the first unit, and the shortfall shows up as a batch that fails the average requirement rather than as a visible defect.
2. Treating nominal capacity as the fill target with no tolerance written. Without a stated band, a factory that fills to the bottom of the band produces a batch that averages under nominal, and an inspector will count that as a labelling non-compliance. It is not a quality dispute; it is a quantity dispute.
3. Declaring volume for a solid or semi-solid product. A cream, gel or powder is declared by weight in both the EU and the US. A pack labelled 500 ml containing a 480 g cream is a misbranded pack, regardless of the bottle’s capacity. Fix the unit before the artwork is drawn, not at the label approval stage.
Frequently asked questions
Is nominal capacity the same as fill volume?
Not exactly. Nominal capacity is the declared quantity; fill volume is what the line delivers. They should match within your stated tolerance, and the line should be set slightly above the nominal figure, never below.
Why is brimful capacity higher than nominal capacity?
Because the difference is the headspace the pack needs. Without it, thermal expansion during storage and transit pushes product past the neck and under the cap.
Do I need brimful capacity on a cosmetic bottle?
Ask for it. It is the only figure that tells you whether your formula has room to expand, and it is the number the cap supplier uses to set the sealing geometry.
Can I fill a bottle above its nominal capacity?
You can physically fill it, but then your net quantity declaration understates what is in the pack, and the label becomes misleading. Fill above nominal only when you have declared the higher figure.
Are capacity and volume interchangeable on a spec sheet?
No. Capacity is what the container can hold; volume is what is in it. If a quotation uses one word where you expected the other, the filling line will be set from the wrong number.
Does temperature change the capacity I fill to?
Yes, and the market rules account for it. Volume is assessed at 20 °C, so a line running warm and a line running cold need different setpoints to deliver the same declared quantity.
About Shijin Packaging
Shijin Packaging Products Co., Ltd. has been manufacturing plastic packaging in Shenzhen, Huizhou and Guangzhou since 2003. We hold more than 2,000 existing moulds, run ISO 9001, GRS and SGS audited production, and ship roughly 500,000 bottles a day. Every quotation we issue states nominal capacity, brimful capacity, empty bottle weight and neck finish together, because a bottle cannot be judged on one number.
Send us the three numbers you need: tell us your target fill volume, the closure you plan to use and the market you ship to, and we will return the nominal and brimful capacities of the closest existing mould so you can size the fill before you commit to tooling.