Slack fill

Two numbers

On this page11

Actual capacity Volume of product contained therein Neither of them is the net quantity on the label Which is why a correct label does not settle it Settling is the dry-product complication So the measurement has to be taken at the right moment Our median container is exactly one gallon And five are at five gallons Which is the practical point about large containers Measure the fill in the container you will ship References

Actual capacity is not the declared quantity. Which is where this goes wrong.

Actual capacity

The volume the container will hold. Our capacity field, published on 37 of 39 containers here, running 950 to 18,927 mL with a median of 3,785.

Volume of product contained therein

What you actually put in. Which for a dry product is a bulk volume and depends on the piece, the moisture and how it settles.

Neither of them is the net quantity on the label

A label declares a net weight or a net volume of product, and the slack-fill arithmetic is about volumes in the container. Three different numbers.

Which is why a correct label does not settle it

A package can declare its net contents accurately and still be filled as to be misleading, because the two rules measure different things.

Settling is the dry-product complication

A product that settles during shipping occupies less volume on arrival than it did at fill. The regulation names that as a functional reason, and it is reason (3).

So the measurement has to be taken at the right moment

A fill volume measured at the filler and a fill volume measured after shipping are different numbers, and only one of them is what a consumer sees.

Our median container is exactly one gallon

3,785 mL, which is a round number in US customary and a conspicuous one. Of the 37 with a capacity, 21 are over a gallon.

And five are at five gallons

18,927 mL, which is a pail. At that scale a modest percentage of slack fill is a visually obvious amount of air.

Which is the practical point about large containers

The same ten percent of empty space is barely visible in a 950 mL jar and is nearly two litres in a five gallon pail.

Measure the fill in the container you will ship

Not in a graduate. Bulk density changes with the vessel, and the regulation is about the vessel.

References

The regulation defines slack-fill as the difference between the actual capacity of a container and the volume of product contained therein. The Davis Pack Supply capacity field is the actual capacity of the container, measured in millilitres and published on 37 of the 39 containers in this group as at 19 October 2026. The volume of product is a property of the buyer's product and we publish no fill volume and no fill weight.

The Davis Pack Supply catalog, measured 19 October 2026. 196 rows: 39 containers and 157 closures, and the largest-capacity shelf in this library. 950 to 18,927 mL with a median of 3,785, which is exactly one US gallon; all 37 containers with a capacity on file are over a quart, 21 are over a gallon and 5 are at five gallons. 32 HDPE and 7 PET, with no glass, polypropylene or metal. 22 white, 8 natural, 7 clear, 1 blue, 1 black. 20 tubs and pails, 10 jars, 9 bottles, and 12 of the 20 are pails. 9 plastic round pails, 5 PE wide mouth containers, 4 HDPE round tubs, 4 HDPE round tubs with handle, 4 plastic square grip containers, 3 HDPE single wall canisters, 2 tight head pails. 20 of the 39 have no neck finish recorded, which are the pails; 8 are at 110-400 and 5 at 120TT. Closures: 111 continuous thread polypropylene lids, 16 metal or aluminum CT caps, 10 dome lids, 7 plastic round pail lids, 6 round tub lids, 3 sealing discs. Liners: 46 heat induction seal, 22 F217, 22 No Liner, 21 unrecorded, 20 pressure sensitive, 10 foam, 8 Plastis standard, 8 PE foam.

Written from 21 CFR 100.100 and from the catalog as it stood on 19 October 2026. That section concerns misleading containers and is not a pet food labeling guide: the guaranteed analysis, nutritional adequacy statement, feeding directions and ingredient definitions that govern a pet food label come from state feed laws and the AAFCO model regulations, which are not federal and are not described here. Our capacity field is the actual capacity of the container, which is one of the two terms in the regulation's own definition of slack-fill; the other is a property of your product.