Plastic Footprint Calculator

How it works

Plastic a year = Σ (items per week × 52.18 × typical mass) + household bottles per month × 12 × 50 g · typical masses: drink bottle 10 g, carrier bag 8 g, coffee-cup lid and lining 4 g, takeaway container 25 g, cutlery set 12 g, straw 0.5 g, wrapper 3 g

Packaging is the largest use of plastic worldwide, and most of it is used once. This calculator counts the single-use items you buy and multiplies them by typical weights: a 500 mL PET bottle weighs about 10 g, a thin supermarket carrier bag 5–10 g (the UK Environment Agency study measured 8.1 g for a standard HDPE bag), a takeaway box 20–30 g. Actual weights vary by brand, so treat the result as an order of magnitude. Reusable bottles, bags and cups remove the most common items with no change in what you buy.

Worked example

Five bottles, four bags, three coffee cups, two takeaway boxes, one cutlery set, three straws and seven wrappers a week, plus three household bottles a month: (5 × 10 + 4 × 8 + 3 × 4 + 2 × 25 + 12 + 3 × 0.5 + 7 × 3) g × 52.18 = 9.31 kg, plus 36 × 50 g = 1.8 kg, for 11.1 kg of single-use plastic a year. A reusable bottle, bag and cup would save 4.9 kg of it.

Sources: UK Environment Agency (2011) Life cycle assessment of supermarket carrier bags · Our World in Data — Plastic pollution

Frequently asked questions