The public are being urged to check ahead to avoid overwhelming charity shops.
WRAP has carried out a survey of 2,400 people which reveals that UK homes are set to dispose of 67 million items of clothing that they've sorted through during lockdown.
Two in five people had a clothing clear-out and most (57%) are storing items to donate to help charities, according to the research.
The data suggests 184 million textile items, like tee-shirts, blouses, jumpers, shoes and handbags, have been cleared out. Outerwear made up the bulk of items the public sorted through (37%) followed by shoes (19%).
The waste body says the charitable sector, local authorities and recyclers should prepare for the expected influx of textiles likely to be donated, as these begin to reopen over the coming weeks.
WRAP's Director Peter Maddox is asking Britons to check ahead before dropping of items to charity shops, a textile bank, retail take-back scheme or kerbside collections. "Everyone can play a role in supporting the charity and textile reuse and recycling sector.
"Our insights tell us that most people prefer to donate or recycle unwanted clothes, but with an unprecedented volume about to be unleashed it’s important that we all take a few simple steps so not to overwhelm the sector.
"Call ahead or look online, check with your local authority, but please never leave clothes in front of a closed charity shop or a full textiles bank."