Net contents and overfill: what NIST Handbook 133 requires, and how much powder to send your co-packer.
Quick answer: Under NIST Handbook 133, a lot's average net weight must meet or beat the label, and no pack can come in lighter than the maximum allowable variation (MAV) allows. Packs under 36 g get an MAV of 10% of label. To meet both rules, co-packers fill slightly over: at North Lakes, label +1% for fills of 30 g and over, +2–3% for 5–30 g and +3–5% under 5 g. If you supply the powder, plan on about 110% of theoretical on small runs, about 105% on large ones.
Every pack we fill holds a little more powder than the label says. That's not sloppiness. It's how a co-packer keeps your product legal on every run. This guide covers the net contents rules, how much overfill is normal, how much powder to send your co-packer, and how fill weights get checked.
What does NIST Handbook 133 require for net contents?
The net weight on your label is a legal claim. FDA's labeling rule (21 CFR 101.105) says what to declare. NIST Handbook 133 is how state weights and measures inspectors check it. It applies to food and dietary supplements sold by weight. Two rules matter:
- The average requirement. The average net weight of the lot must meet or exceed the label weight. A lot that's under on average fails, even if every pack is close.
- The individual limit. Packs can't run lighter than the label minus the maximum allowable variation (MAV). Inspectors allow only a set number of these, based on sample size. Our policy allows none.
What is the maximum allowable variation (MAV)?
The MAV is how far a single pack may run under its label weight. It comes from Table 2-5 of NIST Handbook 133. For packs under 36 g, the MAV is 10% of the label weight. Above that, it's a fixed number of grams that grows with pack size.
| Label weight | MAV | Lightest legal pack |
|---|---|---|
| 1 g | 0.1 g (10%) | 0.9 g |
| 5 g | 0.5 g (10%) | 4.5 g |
| 10 g | 1.0 g (10%) | 9.0 g |
| 30 g | 3.0 g (10%) | 27.0 g |
| 100 g | 7.2 g | 92.8 g |
| 227 g (8 oz) | 12.7 g | 214.3 g |
| 340 g (12 oz) | 16.3 g | 323.7 g |
| 454 g (1 lb) | 19.9 g | 434.1 g |
| 907 g (2 lb) | 31.7 g | 875.3 g |
Source: NIST Handbook 133 (2026), Table 2-5, packages labeled by weight. Meat and poultry under USDA use a different table. Example: a 5.1 g sachet can't have a pack under 4.59 g.
Why can't a co-packer fill exactly to label weight?
Because no filler puts the same weight in every pack. Fill weights spread a little above and below the target. Set the target at label weight and about half the packs land under. The lot average can then slip below label and fail the average requirement.
A small overfill shifts the whole spread up. The average sits safely over label, and the lightest packs stay well above the MAV floor.
How much overfill is normal?
Usually 1–5%, depending on fill size. The smaller the fill, the bigger the overfill. An auger's variation is roughly fixed in grams, so it's a larger share of a 2 g stick pack than a 340 g pouch. These are our standard targets:
| Label fill | Standard target | Example: label → target |
|---|---|---|
| 30 g and over | Label +1% | 340 g → 343.4 g |
| 5–30 g | Label +2–3% | 10 g → 10.2–10.3 g |
| Under 5 g | Label +3–5% | 2 g → 2.06–2.10 g |
We set the exact target within the range once we see how your powder runs on our filler.
Need it tighter, like +1% on a 5 g fill? We can do that with 100% checkweighing or extra sampling. It takes more time and labor, so it's priced accordingly.
How much extra powder should I send my co-packer?
On toll jobs, plan on about 110% of theoretical on small runs and about 105% on large ones. Theoretical is units × label weight. You supply the powder, so the overfill comes out of your material.
That margin covers two things:
- Overfill: the target above label, from the table above.
- Process loss: powder left in the hopper (the heel), startup and setup packs, and rejects pulled at the checkweigher.
Example: 10,000 sachets at 10 g is 100 kg theoretical. Send about 110 kg (about 105 kg on a large run). Send less and the run ends short of your unit count.
Small fills and short runs sit at the high end of that range. Startup loss and the hopper heel are fixed amounts, so they're a bigger share of a small job. Film and other packaging have their own loss; see our yield loss guide.
Filling to label isn't the safe choice. Filling a little over is.
How do co-packers check fill weights?
At North Lakes, every run is checkweighed or sample-weighed, and every weight is recorded.
- Inline checkweigher where its accuracy fits the fill. It weighs every pack and rejects light ones.
- Lab balance for tiny fills (1–5 g). A checkweigher can't resolve these well enough. We pull about 10 packs every 15–30 minutes and weigh them on a 0.001–0.01 g balance.
- Film tare per roll. We weigh empty packs from each new roll and subtract that from gross weight, so film variation doesn't hide a light fill.
- Logged records. Weights, times and adjustments go on the batch record. You can ask to see them.
Our scales are checked daily with certified, NIST-traceable test weights.
Who is responsible for net contents: the brand or the co-packer?
Both, for different things. The brand owns the formula, label claims and shelf life, including the net weight printed on the pack. The co-packer owns filling to that spec and releasing product against it.
For dietary supplements, the fill target and the upper and lower limits go in the master manufacturing record (MMR), which you approve before the first run. We fill and release against it.
Net contents FAQ
Is overfill just giving product away?
A little, by design. It's much cheaper than a failed inspection, a relabel or a recall.
Can a co-packer fill tighter than its standard target?
Yes, with 100% checkweighing or extra sampling. We can run closer to label, like +1% on a 5 g fill. It costs more, and we'll quote it.
What happens if I send less powder than you recommend?
We fill until the powder runs out. You'll get fewer units than ordered, not lighter packs.
Can I see the fill weight records for my run?
Yes. Every run's weights are logged on the batch record. Ask and we'll send them.
Does the MAV apply to stick packs and sachets?
Yes. Any pack labeled by weight is covered. Under 36 g, that's 10% of label, so a 7 g stick pack can't have a pack under 6.3 g.
Our fill-weight policy
This is the wording on our quotes and quality agreements:
We fill to comply with NIST Handbook 133: the lot average meets or exceeds label weight and no individual package falls below the maximum allowable variation. Standard fill target is label +1% for fills of 30 g and over, +2–3% for 5–30 g, and +3–5% under 5 g. Each run is checkweighed or sample-weighed and recorded.
Related reading
- What is yield loss in co-packing?
- How to prepare for co-packing
- Proof-of-concept runs
- Sachet vs. stick pack
- Questions to ask a co-packer
Sources
- NIST Handbook 133, Checking the Net Contents of Packaged Goods (2026), Table 2-5.
- 21 CFR 101.105, Declaration of net quantity of contents.
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