Calculate | No Plastic Uniforms

Calculate your school uniform's impact

The math is easy

How to Calculate Your Uniform's Emissions

First, weigh each 100% polyester item separately

Convert kilograms to grams. You'll need both.

Carbon Emissions

Add the weight in kilograms of all your uniform items together:

PE kit + blazer + other = W(kg)

Making 1kg of polyester releases 14.2kg of CO2. To calculate the carbon emissions of your uniform, take the total weight (W) and multiply by 14.2.

W(kg) x 14.2 = CO2 (kg)

This is how much carbon is released to make your uniform.

Micro-plastic Emissions in Water

Between 700 and 4000 micro-plastic fibres are released per gram in a single wash. So take the weight of your item in grams (W) and multiply by 700 and 4000, and then multiply by the number of washes per year (N). You'll have to calculate your blazer, which gets washed less, separately from your PE kit that gets washed more (see box).

W(g) x 700 x N = Min

W(g) x 4000 x N = Max

This will give you the range of micro-plastic fibre release per uniform item. Add all the Min results together and then the Max results, and this will give you the total range for your uniform for a year.

How many times does your uniform get washed?

PE kit, and shirts will probably get washed more often than trousers and blazers. UK students are in school for 39 weeks, or 9 months, and over 3 terms. So if your PE kit gets washed twice a week, (N) is 39x2=78 washes

Micro-plastic Emissions in the Air

We release three times more micro-plastic fibres in the air while we are moving around in our clothes, as when we wash them. Multiply the results from your uniform's micro-plastic release in water by 3.

Min x 3 = Min air

Max x 3 = Max air

This is how much micro-plastic your uniform releases in a year.

How to Calculate Emissions for your Class or Year Group...

Multiply each result above by the number of students in your class or year-group. Easy.

NOTE: some people may buy second-hand, or get their uniform from an older sibling, in which case, they are not adding any new carbon. You can make your calculation more accurate by estimating how many people wear second-hand, or running a survey.

... and for your whole school

To get the most accurate number of carbon and micro-plastic emissions for the students in your whole school, you should get every year group to do their own calculations. Bigger-sized clothing weighs a little bit more, and therefore will release more carbon and more micro-plastic fibres.

Huangshali Channel, northeast of Guotai Dyeing Factory, 2011. Qiu Bo/Greenpeace

Chemicals

Call or email your uniform supplier and ask them to tell you what chemicals are used in your uniform's dyes and finishes. The first step is to find the right person at your school's supplier, and then email politely, but persistently until you get an answer. A few tips:

Ask your supplier's customer service for their sustainability manager or your school's account manager;
Your deputy head, or head teacher can also help you find your school's account manager;
Ask your school's parents' association and Board of Governors for help.

Not getting an answer is not failure: you have let the company know that customers are concerned about chemicals; the more people who do this, the stronger the signal to the industry that they need to be transparent and consider the health impacts of their uniforms. Report the supplier's non-response to your school, and urge them to change to a supplier that is transparent.

Make a Presentation

Now that your have all your data, make a presentation. Design your own avatar to tell the story. Explain how climate change works, and how micro-plastics get into our water and air, and the dangers of chemicals for students, the workers who make our clothes and the planet.

Your calculations will give your school an idea of the size of the problem, and most importantly, show that there is an opportunity to make our uniforms better for us, factory workers and their communities, and the planet.