The cradle to grave carbon footprint of a cardboard box is 0.94 kg CO2e / kg.

The cradle to grave carbon footprint of flat cardboard is 1.53 kg CO2e / kg.

A common e-commerce box that is 9 x 9 x 9 inches is estimated to emit 0.27 kg CO2e, which is the equivalent of 3.0% of a gallon of gasoline.

Cardboard boxes combine walls of cardboard with corrugated, or folded, strips of cardboard that add strength to the walls of the box. The corrugated cardboard is bonded to the walls of the box with an adhesive, or glue. Cardboard boxes are often unbleached, but some cardboard boxes also contain printed surfaces, which also contributes to the environmental impact of a cardboard box.

The greenhouse gas emissions for common box sizes is based on Uline (2021A,B,C,D,E), and is shown in the table below:

Data and Assumptions

Carbon footprint of corrugated cardboard boxes is based on the review paper Brogaard et al. (2014), which performed a literature review of the life cycle inventory of recycled products. Carbon footprint of primary source (virgin) corrugated cardboard is based on 17 studies, with a mean of 1.14 kg CO2e / kg, and a standard deviation of 0.45. The carbon footprint of secondary source (recycled) corrugated cardboard is based on 11 studies with a mean of 0.82 kg CO2e / kg, and a standard deviation of 0.31. The greenhouse gas emissions of recycled cardboard boxes are 28.1% lower than primary source cardboard boxes.

The carbon footprint of non-corrugated, or flat cardboard, is also based on Brogaard et al. (2014). The carbon footprint of primary source cardboard is based on 8 studies, with a mean of 1.85 kg CO2e / kg, and a standard deviation of 0.99. The carbon footprint of secondary source cardboard is based on 1 study, with a value of 0.61 kg CO2e / kg. Due to lack of data, Consumer Ecology assumes the same reduction in greenhouse gas emissions from recycled cardboard boxes of 28.1%.

Percentage of recycled cardboard is based on the EPA Paper and Paperboard (2021) dataset, which states that 45,970 thousand US tons of paper and paperboard were recycled in 2018, out of a total of 67,390 thousand US tons of paper and paperboard that entered the US waste stream. Therefore, 68.2% of paper and paperboard were recycled in 2018.

Consumer Ecology assumes a loss of 10% of recycled material to become new materials (PPEC, 2011), and thus the total recycled content of cardboard is estimated to be 61.4%. Based on this assumption the carbon footprint of corrugated cardboard is 0.94 kg CO2e / kg and the carbon footprint of cardboard is 1.53 kg CO2e / kg.

System boundaries are not defined in Brogaard et al. (2014), however Consumer Ecology assumes that in order to compare primary to secondary source materials, that a full life cycle (Cradle to Grave) perspective is required, as secondary source materials require assumptions about primary production and recycling rates during the waste recovery process. Otherwise, the two products would not be comparable, as intended by the study.

The carbon footprint values stated do not include biogenic carbon sequestration from the waste recovery process.

References

Brogaard, L. K., Damgaard, A., Jensen, M. B., Barlaz, M., & Christensen, T. H. (2014). Evaluation of life cycle inventory data for recycling systems. Resources, Conservation and Recycling, 87, 30-45.
 
EPA: Environmental Protection Agency. (2021). Paper and Paperboard: Material-Specific Data. See Link to Source
 
PPEC: The Paper and Paperboard Packaging Environmental Council. (July, 2011). Understanding Recycled Content (any why requiring minimum levels is not the answer for paper packaging). See Link to Source
 
Uline. (2021A). 6 x 6 x 6″ Corrugated Boxes. See Link to Source
 
Uline. (2021B). 9 x 9 x 9″ Corrugated Boxes. See Link to Source
 
Uline. (2021C). 12 x 12 x 12″ Corrugated Boxes. See Link to Source
 
Uline. (2021D). 16 x 16 x 16″ Corrugated Boxes. See Link to Source
 
Uline. (2021E). 24 x 24 x 24″ Corrugated Boxes. See Link to Source