What this is
- A family calculator that turns "how many of these do we use in a week?" into kilograms of plastic a year, compares it with your country's average, and shows what each swap would save.
- Unlike most footprint calculators, every weight and every benchmark it uses is printed here, with the source, so you (or a class) can check the working or do it by hand.
- Made and funded by No Plastic Today. Licence: CC BY 4.0. No login; nothing leaves your browser unless you choose to save a pledge (totals only).
How to use it (5 minutes)
- Simple mode shows the eight items most households use. "More options" reveals the rest.
- Enter how many of each you use per week (or per year for toothbrushes and razors, per month for toy and gift packaging). Estimate; you can refine after a week of noticing.
- Enter household size and country.
- Read the result: kg per household per year, kg per person, "that is the same as ___ 500 ml bottles", and your country comparison.
- Toggle "reusable" on any line to see the grams avoided per year and the honest break-even (how many times you must use the reusable before it beats the throwaway).
The maths
- Annual grams = sum over items of (count per week x 52 x unit weight in grams). Per-year items are multiplied by 1; per-month items by 12.
- Per person = annual grams / household size.
- Bottles equivalent = annual grams / 10 (a small still-water bottle is about 10 g).
- Optional carbon estimate = annual kg x 3.9 kg carbon dioxide equivalent (CO2e) per kg of plastic. This is a rough lifecycle average derived from the Organisation for Economic Co-operation and Development (OECD)'s figures of 1.8 billion tonnes CO2e for about 460 million tonnes of plastic in 2019 (OECD Global Plastics Outlook, 2022: oecd.org/en/publications/global-plastics-outlook_de747aef-en.html). It is labelled "estimate" on screen.
Unit weights used (grams)
- Drinks bottle up to 750 ml: 10 g still, 18 g carbonated. Sources: European Commission single-use plastics study 2018, Table A2.1 (ec.europa.eu/environment/pdf/waste/Study_sups.pdf); industry summaries (bottlefirst.com/what-does-a-water-bottle-weigh/).
- Large bottle 1–2 litres: 45 g (EC 2018 EU market average is 36.4 g across all sizes; large bottles sit above it).
- Carrier bag, single-use HDPE: 8.12 g (UK Environment Agency carrier-bag life-cycle assessment (LCA) 2011, Table 3.1: biodeg.org/wp-content/uploads/2021/04/uk-ea-publishes-lca-of-supermarket-carrier-bags-.pdf).
- Produce or bread bag: 2 g (our estimate; labelled).
- Takeaway coffee cup 11 g plus lid 3 g (EC 2018).
- Cold cup, lid and straw: 10 g plus 3 g plus 0.4 g (EC 2018).
- Takeaway container: 20 g (EC 2018 estimate).
- Ready-meal tray: 20 g (as above).
- Yoghurt or dessert pot: 5 g (our estimate; labelled).
- Crisp or sweet packet: 5.43 g (EC 2018).
- Cling film: 3 g per metre (our estimate from film thickness; labelled).
- Wet wipe: 1.1 g dry (EC 2018).
- Cotton bud, plastic stem: 0.23 g (EC 2018).
- Disposable cutlery: 2.6 g per piece (EC 2018).
- Sanitary towel: 6.2 g, of which about 36% is plastic (European Commission 2018, citing EDANA, the nonwovens and hygiene products industry association); the calculator counts the plastic fraction.
- Toothbrush: 18 g, four per year (Plastic Pollution Coalition fact card; measuringly.com/how-much-does-toothbrush-weigh/).
- Disposable razor: 10 g (our estimate; labelled).
- Toy and gift packaging: 30 g per month (our estimate; labelled).
Break-even figures for the swap toggle
- Bag for life (LDPE): 4 uses. Non-woven polypropylene bag: 11 uses. Cotton bag: 131 uses. Paper bag: 3 uses. All versus a single-use HDPE bag on global warming potential (UK Environment Agency 2011, executive summary).
- Reusable cup: the calculator uses a system weight of about 96 g (EC 2018, Table A2.3) and shows "you are ahead after about 7 cups" on plastic mass alone; the carbon break-even is higher and depends on how the cup is washed, so we do not give a single number.
- Steel straw 13.9 g, silicone straw 8.2 g, paper straw 0.8 g (EC 2018, Table A2.3).
Country benchmarks
- Plastic waste per person, 2019: United States 221 kg; OECD Europe 114 kg; Japan and Korea 69 kg; China 47 kg; India 14 kg (OECD Global Plastics Outlook, chapter 2: oecd.org/en/publications/global-plastics-outlook_de747aef-en/full-report/component-7.html).
- Single-use plastic waste per person, 2019 (closest to what this calculator measures): Australia 59 kg, United States 53 kg, South Korea 44 kg, United Kingdom 44 kg, China 18 kg, India 4 kg (Plastic Waste Makers Index 2021, by the Minderoo Foundation, a philanthropic organisation: cdn.minderoo.org/assets/uploads/resources/plastic-waste-makers-index-2021/20211105-plastic-waste-makers-index.pdf).
- Where neither source gives a national figure, the country picker falls back to Our World in Data's per-capita series (2010 vintage, labelled as such; CC BY 4.0: ourworldindata.org/grapher/plastic-waste-per-capita).
Reading your result honestly
- This counts packaging you handle at home. It does not count the plastic used to grow, make and ship what you buy, which can be large. Treat your number as "the part I can change this month".
- Reusables only win if they are reused. The break-even numbers are there so nobody buys ten cotton bags and calls it a day.
- The biggest single lines for most households are drinks bottles, produce bags and snack packets. Start there.