Climate and science.
Thousands of people will take part in a national survey on how much they consume.
The count is put together by Everyday Plastic.
According to research, the US uses more plastic per person than the UK.
The count will shed light on how households consume material that is harmful to the environment.
Huge amounts of energy and fossil fuels are needed to make new plastic, and it sticks around in our environment for a long time. It's only possible to recycle plastic two or three times.
There are microplastics found in everything from human blood to snow.
From 16 to 22 May, around 151,000 households, 96 MPs, and 4,180 classrooms will be recording their plastic use.
Government figures show that UK households recycled 42% of their waste in 2020.
Some of the plastic that is put in the recycling bin goes to landfill or to be thrown away. The plastic waste was sent from the UK to Turkey.
This count is the UK's biggest ever investigation of plastic. Millions of us do our part to recycle, but we don't know where our plastic waste ends up.
The founder of Everyday Plastic filled 40 bin bags with waste.
This experience changed my life and made me understand the problem in a different way. I wondered if other people would do the same experiment as I did.
Participants in the Big Plastic Count receive a pack explaining how to count the plastic in 19 categories. They tally up each type of plastic waste before putting it in the bin.
The data will be analysed by Everyday Plastic to produce a national picture of plastic waste.
Radical action by the government and supermarkets is required to reduce how much plastic is produced.
Maria Hughes, who lives in Newport, Wales with her husband and two children, said she is taking part because she feels like we are dying in plastic.
I can't achieve the change on my own. We need manufacturers and supermarkets to change the packaging of our food.
Retailers have been committed to removing single-use packaging for some time. Many have signed up to the Plastics Pact, working with suppliers to eliminate problematic or unnecessary single-use plastic packaging. UK supermarkets are investing in their reuse/refill offerings to cut down on packaging.
The government wants to introduce a deposit return scheme and other measures to reduce plastic waste.