Our calculation methodology.

This page provides additional detail about some of the calculations behind our sustainability messages

Total bottles transformed

How we calculated that 166,749,658 single-use plastic bottles have been transformed into our signature thread.

As of September 1, 2023, Rothy’s has purchased 1,542,434 kilograms of yarn, which is made from 100% post-consumer recycled plastic bottles, as certified by the SCS Recycled Content certification.

To calculate the total bottles transformed, we use a representative 16.9-ounce bottle weighing 9.25 grams, the average weight of a water bottle in 2014 according to Beverage Marketing Corp. There is no standard bottle weight, and the weights of plastic bottles vary across brands and markets, so we use this representative bottle weight to account for that variability.

In the recycling process, there is some material loss due to color variations, quality and other factors. Because of this material loss, the total number of bottles collected to make 1,542,434 kilograms of yarn could be greater than 166,749,658 bottles.

1,542,434 kilograms = 1,542,434,340 grams / 9.25 grams of plastic per bottle = 166,749,658 bottles

Total ocean-bound marine plastic

How we calculated that 603,167 pounds of ocean-bound marine plastic have been turned into the thread we use for our bags and accessories.

As of Sept. 1, 2023, Rothy’s has purchased 273,592 kilograms (603,167 pounds) of ocean-bound marine plastic yarn. The yarn is OceanCycle certified, verifying that the plastic was collected within 30 miles proximity to the coastline.

In the recycling process, there is some material loss due to color variations, quality and other factors. Because of this material loss, the total amount of ocean-bound marine plastic collected to make 273,592 kilograms of ocean-bound marine plastic yarn could be greater than 603,167 pounds.

Total plastic bottles per shoe

How we calculate the number of plastic bottles that it took to knit each shoe type.

To calculate the number of plastic bottles that it took to knit each shoe type, we use the weight of rPET yarn used in the upper for the standard sample size of that style of women’s, men’s or kids’ shoes. The women’s sample shoe is size 7, the men’s sample shoe is size 9, and the kids’ sample shoe is kids’ size 13.

To calculate how many bottles, we use a representative 16.9-ounce bottle weighing 9.25 grams, the average weight of a water bottle in 2014 according to Beverage Marketing Corp. There is no standard bottle weight, and the weights of plastic bottles vary across brands and markets, so we use this representative bottle weight to account for that variability. 

For example:

The rPET knit for the upper of The Point in women’s size 7 weighs 106.3 grams.

106.3 grams of rPET knit in the upper / 9.25 grams of plastic per bottle = 11.4 bottles.