Short answer
Work out void fill by subtracting the product volume from the internal box volume, then allow around 30% extra because most fill compresses in transit. As a rule of thumb, aim for at least 50 mm of fill between the product and every wall of the box, and no more than about 40% of the box being empty space.
The calculation
Internal box volume minus product volume gives the void. A 400 x 300 x 250 mm box is 30 litres. A product occupying 18 litres leaves a 12 litre void, so you need roughly 15 litres of fill once compression is allowed for. If the void is more than about 40% of the box, the cheaper fix is a smaller box, not more filler.
Which fill to use
| Type | Best for | Notes |
|---|---|---|
| Paper void fill | General cushioning and blocking | Kerbside recyclable, widely accepted |
| Air pillows | Light goods, high volume packing | Very low cost per litre, needs a machine |
| Loose fill | Awkward shapes | Settles in transit, allow extra |
| Honeycomb paper wrap | Fragile items needing wrap and fill | Plastic-free alternative to bubble |
Cheaper than filling the gap
Void fill is the symptom, not the cause. If you are buying a lot of it, a right-sized box usually removes the cost of the fill and reduces carriage at the same time. We make boxes to exact internal dimensions in Letchworth, so right-sizing rarely carries a premium.
Frequently asked questions
- Is paper void fill recyclable?
- Yes, paper void fill goes in standard cardboard and paper recycling streams.
- Do I need a machine for void fill?
- Not for hand-tear paper or honeycomb wrap. Air pillows and high-volume paper systems need a converter, which we can supply.
- Can you supply void fill and boxes together?
- Yes, boxes, fill, tape and protective materials all ship on one order, one delivery and one invoice.
Think your packaging is bigger than it needs to be?
Send us your product dimensions and we’ll come back with a right-sized option. There is no minimum on stock lines, and bespoke corrugated runs can start from as little as one, but we will advise the most cost efficient run rate depending on size and board grade.
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