Bulk density · Fill

Bulk density calculator for bags and containers

Know what fits in the big bag before the order is placed.

Enter bulk density or a weighed sample, plus the package volume, and get the fill weight in lb or kg.

Last updated 2026-09-27. Math runs in your browser, no data leaves your computer.

Start with the bulk density of the product you are packing. If the technical data sheet lists one, type it in, and if it does not, fill a measuring cylinder or a box of known volume, weigh it, and let the tool do the division.

A measured sample beats a data sheet figure when the lot has settled in transit, because tapped density runs higher than poured density.

Take the value from the technical data sheet and note whether it is poured or tapped, since the two can differ enough to change the bag count.

Package volume and weight limit

Type the usable volume of the package you plan to fill. Bag and container volumes vary by supplier and build, so take them from the specification sheet rather than a generic figure.

The choice only labels the answer, and the volume you type below does the work.

Use the fill volume on the bag or container specification, because outside dimensions overstate what a bulging bag or a lined container really holds.

For a big bag this is the safe working load printed on the label, and for a container it is the payload limit, so the fill never exceeds the rating.

Before the booking, screen the name on the invoice. Shipment pre-check is on the paid plans, from USD 59 a month.

General guidance only. Verify against the cited primary sources before you commit to a shipment, declaration, or contract.

How bulk density sets the fill

Buyers order powders by weight and factories pack them by volume, and bulk density is the bridge nobody checks until the goods arrive. A light product ordered in 1,000 kg big bags either ships in half full bags, arrives in more bags than the booking allowed for, or gets packed into bags the factory overfilled past their rating.

The tool converts every input to kg/m3 first. A sample gives grams divided by milliliters, which equals g/mL, and multiplying by 1,000 gives kg/m3. The fill by volume is bulk density times usable volume, and when you add a weight limit the tool reports the lower of the two as the real fill.

Unit factors come from NIST Special Publication 811: 1 lb/ft3 is 16.01846 kg/m3, 1 ft3 is 0.02831685 m3, 1 US gallon is 3.785412 L, and 1 lb is exactly 0.45359237 kg.

Worked example: 1,000 kg big bags of a light powder

The booking. A buyer orders 20 metric tons of a powder packed in 1,000 kg big bags, and the bag supplier specifies 1.0 m3 of usable volume with a 1,000 kg safe working load. Twenty bags at the rated load cover the order exactly, and the booking looks fine on paper.

The failure. The data sheet lists a bulk density of 0.55 g/mL, which is 550 kg/m3 or 34.34 lb/ft3, so a 1.0 m3 bag holds only 550 kg before it is full. The factory can ship 37 bags instead of 20 and blow the space on the booking, or overfill a bag it cannot close, so either the bag changes or the order quantity per bag changes.

The fix. Run the density through the tool and it shows that 1,000 kg needs 1,000 / 550 = 1.82 m3 of usable volume. The buyer either specifies a bag with at least that volume and the same rating, or accepts 550 kg bags and books space for 37 of them, and the goods ship on the plan everyone signed.

Working out how many drums or IBCs fit on a pallet and in a container rather than bags? The drum and IBC palletising calculator lays out the pallets and gives the count per container.

Need the freight bill on a light cargo where volume drives the rate? The chargeable weight calculator compares actual and volumetric weight for sea, air and courier.

Frequently asked

How do I convert bulk density from lb/ft3 to kg/m3?

Multiply lb/ft3 by 16.01846 to get kg/m3, the factor published in NIST Special Publication 811. Going the other way, divide kg/m3 by 16.01846, so a powder at 550 kg/m3 is 34.34 lb/ft3. A reading in g/mL is the same number as kg/L, and multiplying it by 1,000 gives kg/m3.

What is the difference between bulk density and true density?

Bulk density includes the air between particles, so it is always lower than the true density of the solid and it is the number that decides how much fits in a bag. The same powder also reads higher once it has been tapped or has settled in transit, so a TDS may list both a poured and a tapped value.

Why does my bag hold less than the tool says?

The tool fills the usable volume you enter completely. Real bags leave headspace for closing and stitching, and big bags bulge rather than filling square, so use the usable volume from the bag specification and not the outside dimensions multiplied together.

Which limit decides the fill, volume or weight?

The fill stops at whichever limit runs out first. A light powder fills the volume before it reaches the safe working load, while a dense one hits the weight limit with space to spare, and the tool shows which of the two binds for your product and package.

Need a factory for this chemical?

Tell us the chemical, grade and quantity. A person on our team in Shanghai sends you a real, checked factory, and your first one is free.

Get your free Factory Match Or talk to our team

Related tools

Sourzi shows what official files say. It is not customs or legal advice. For a binding answer, ask a licensed customs broker, a CBP ruling or an Australian Border Force Tariff Advice.

File dates and links are on Data sources.