VOID FILL PLANNING
How Much Void Fill Do I Need?
Use empty volume as a planning bound, then measure a representative pack because material behavior and product geometry control real usage.
SHORT ANSWER
Start with the inputs you can verify
Start with carton internal volume minus the volume displaced by the packed product and inserts. That difference is an upper-bound planning estimate, not an order quantity: irregular shapes, compression, settling, and intentional air spaces change actual use. Choose material for the required job—blocking, bracing, cushioning, or surface protection—then weigh or meter several representative packs and base purchasing on the measured average plus documented process variation.
Calculate empty volume carefully
Use internal carton dimensions. Subtract the displaced volume of products, dividers, trays, and fixed cushioning; do not subtract a product’s bounding box if large open spaces inside that box cannot actually accept fill.
For multiple items, model the intended arrangement. A layout change can alter void geometry even when total product volume stays the same.
Estimated empty volume = internal carton volume − displaced packed-component volumeMatch the material to the function
Void fill is often asked to do several jobs at once. Blocking and bracing limit movement; cushioning manages shock; wrapping protects surfaces; fill occupies otherwise empty regions. A volume result alone cannot tell you whether a material provides adequate protection.
Loose paper, air pillows, foam, and molded materials have different bulk density, compression, recovery, and settling behavior. Convert volume to mass or item count only with supplier data or a measured packing trial for the chosen material and packing method.
| Factor | Effect on estimate | Control |
|---|---|---|
| Irregular product shape | Bounding volume overstates displacement | Trial the intended orientation |
| Material compression | Loose volume changes under closure | Measure closed packs |
| Settling in transit | Restraint may decrease | Use validated packing method |
| Operator variation | Usage varies pack to pack | Standard work and sample checks |
Worked example: convert trials into a purchase quantity
A 1,000-unit order packed 12 per carton needs 84 cartons before waste. If three trial packs average 1.5 L of kraft paper and one divider per carton, a 5% planning allowance gives 133.35 L of paper and 89 dividers before supplier pack rounding. The material-bill worksheet makes those component assumptions visible.
Keep the 84-carton base requirement, measured trial range, material option, and 5% allowance in the job record. If the last carton uses a different configuration, model it separately instead of silently assuming every carton is identical.
Turn a pack trial into a purchase estimate
Pack several representative cartons using the proposed standard work. Measure material by weight, length, sheet count, or pillow count—whichever purchasing unit can be controlled. Record the average and range, then multiply by forecast carton count and add only a documented setup or process allowance.
A shake check can reveal obvious movement but is not a substitute for distribution testing. Use relevant carrier guidance and an appropriate test protocol when product risk warrants it.
- Use production carton and fill materials, not convenient substitutes.
- Include all accessories, documentation, and inserts.
- Measure closed external dimensions and packed weight.
- Define acceptance criteria for movement and product condition.
- Revalidate after product, carton, supplier, or packing-method changes.
A practical workflow
- Calculate the carton’s internal volume and estimate displaced packed volume.
- Identify whether the pack needs restraint, cushioning, surface protection, or a combination.
- Run several production-representative packing trials.
- Measure actual material use in the purchasing unit and document variation.
- Validate the pack, then scale measured usage to forecast volume.