Packaging is often a brand’s most visible and most measurable emissions source, and the choice of material matters more than weight: a few grams of aluminium can outweigh a heavy paper carton. This calculator totals the cradle-to-gate carbon of a multi-component pack and scales it to your annual volume.
How it works
Each component blends a virgin and a recycled emission factor by its recycled content, then the components are summed:
blended factor = virgin × (1 − recycled%) + recycled × recycled%
component CO2e = weight (kg) × blended factor
per-unit CO2e = sum of all components
annual CO2e = per-unit CO2e × annual volumeBecause recycled grades carry far lower factors, raising recycled content shifts the blended factor toward the cleaner value — the simplest way to cut a pack’s footprint without redesigning it.
Approximate emission factors by material
These figures are representative of UK DEFRA guidance ranges for material production. Actual published DEFRA factors should always be confirmed before use in official reporting.
| Material | Virgin factor (approx kg CO2e/kg) | Recycled factor (approx kg CO2e/kg) |
|---|---|---|
| PET plastic | ~2.2 | ~1.0 |
| HDPE plastic | ~2.0 | ~0.9 |
| Glass | ~0.9 | ~0.5 |
| Aluminium | ~9–12 | ~0.4–0.6 |
| Steel | ~2.3 | ~0.5 |
| Cardboard / paperboard | ~0.9 | ~0.5 |
| Corrugated board | ~0.7 | ~0.4 |
The aluminium row stands out. At 9–12 kg CO2e/kg for virgin metal and ~0.5 for recycled, the range is almost 20:1. A single 10 g aluminium cap can carry 0.09–0.12 kg CO2e — more than a 200 g glass bottle at 50% recycled cullet. This is why the lightest component is sometimes the biggest contributor.
Worked example: a glass bottle with an aluminium cap
A beverage brand uses a 200 g glass bottle (0% recycled cullet), a 3 g aluminium cap (50% recycled), and a 2 g paper label (30% recycled). Using approximate factors:
- Glass bottle: 0.200 kg × 0.9 = 0.180 kg CO2e
- Aluminium cap: 0.003 kg × (9 × 0.5 + 0.5 × 0.5) = 0.003 × 4.75 = 0.014 kg CO2e
- Paper label: 0.002 kg × (0.9 × 0.7 + 0.5 × 0.3) = 0.002 × 0.78 = 0.0016 kg CO2e
- Per-unit total: approximately 0.196 kg CO2e
At 1 million units per year, that is about 196 tonnes CO2e annually from packaging material production alone. Switching the glass to 50% recycled cullet would reduce the bottle’s contribution to roughly 0.140 kg CO2e — saving around 40 tonnes CO2e per year across the volume.
What this does and does not cover
This calculator covers cradle-to-gate material production — the carbon embedded in making the packaging material from raw inputs. It does not cover:
- Transport of packaging materials to your filling site
- Energy used in the filling and sealing process
- Distribution of the finished product to retail or consumer
- End-of-life emissions or credits (recycling, landfill, incineration)
For a full lifecycle assessment (LCA), these additional stages need to be added. The material production stage is typically the largest single contributor for most packaging types, which is why it is the standard starting point for hotspot analysis.