-Jim Yu

Last week, a European client sent an RFQ for a custom 100ml glass jar for organic honey.

Confidently, he said: “Just design the label and carton for 100g.”

I replied: “100ml of honey weighs roughly 140g.”

He paused, then said: “Thank you — you just saved my entire shipment.”

This scenario is far too common in the packaging industry.

Many buyers, and even some suppliers, automatically equate milliliters with grams.

But as a professional packaging customization partner, it’s our responsibility to help clients avoid this hidden cost trap.

Why ml ≠ g

· Water: density ≈ 1.0 → 100ml ≈ 100g

· Honey, jams, concentrates: density ≈ 1.4–1.5 → 100ml ≈ 140–150g

· Cooking oil, emulsified sauces: density ≈ 0.9 → 100ml ≈ 90g

· Beverages with particles (pulp, coconut jelly): uneven density → must be tested

When clients assume 1:1 conversion for packaging, labeling, cartons and logistics, serious issues follow:

❌ Mismatched net content labels (violating market regulations)

❌ Overweight containers (fines during sea freight)

❌ Sufficient volume but insufficient fill weight (customer complaints)

Real Impacts on Custom Packaging

1. Bottle Design

A fixed-volume container (e.g., 100ml) must account for the actual product weight to determine wall strength and stacking layers.

For the same 100ml capacity, honey jars require a base 0.2–0.5mm thicker than water bottles to prevent breakage in transit.

2. Labeling & Compliance

Many regions require both volume (ml/L) and net weight (g/kg), or at minimum accurate labeling.

Printing “100g” while filling 140g counts as false labeling.

3. Cartons & Container Loading

A 20ft container typically allows a gross weight of 18 tons:

· Water: full volume within weight limit

· Honey: same number of jars → 40%–50% overweight → must reduce quantity or use smaller bottles

Sharing density conversion upfront prevents full-container rejections.

4. Cost & Quotation

Packaging is quoted per piece (FOB), but ocean freight is charged by weight or volume — whichever is higher.

Clients focusing only on volume often face unexpectedly high logistics costs.

A trusted supplier provides a clear ml–g–carton quantity–container weight breakdown.

Three Professional Tips for the Packaging Industry

1. Obtain real density data before sampling

Ask for a 200ml product sample or third-party density test report.

2. Create a common food density reference card

Add it as a value-added tool with your quotation:

· Water / beverage → 1.0

· Milk → 1.03

· Tomato paste → 1.2–1.3

· Honey → 1.42

· Peanut oil → 0.92

3. Mark both full capacity and recommended filling weight on drawings

Prevent clients from simply matching volume to weight.

If you’re in food, cosmetics, or personal care packaging, don’t let the density trap ruin your compliance, logistics, or reputation.

As your reliable packaging partner, we turn technical details into cost savings and risk reduction.