Environmental campaigners fear the discarded face coverings could spend hundreds of years in the ground, with an estimated 20,000 tonnes expected to be dumped in the UK by March 2021 - a year after the coronavirus pandemic began.
Face coverings weigh approximately 3.5g each and data was established by predicting how many face masks would be thrown away in the next four months.
In Scotland, it has been mandatory to wear face coverings in retail, hospitality and public transport since July, except for people with a medical exemption.
According to TradeWaste, which carried out the research, the main problem with disposable face masks is that they are made from heated and pressed plastics and cannot easily be recycled.
The figures come after a major beach clean across Scotland last month found personal protective equipment (PPE) on almost a quarter of beaches.
Charlotte Green from TradeWaste said: "6.3 billion face masks is the amount the UK will throw in the bin in just four months - if the rules on mask wearing continue throughout 2021, this could top 19.2 billion."The numbers are absolutely mind blowing."
Glasgow is expected to see the most amount of face coverings being sent to landfill, with a staggering 176 tonnes predicted to be sent to the dump by March.
Edinburgh is not too far behind, with a predicted 146 tonnes being dumped - while Inverness and Dundee could see 24 and 44 tonnes dumped respectively.Campaigners across Scotland have now urged people to move away from all single-use items.
Sarah Moyes, circular economy and plastics campaigner at Friends of Earth Scotland, said: "Single-use disposable masks have become a symbol of global plastic pollution and it's clear they cause huge environmental problems.
"Not only are these plastic masks littering our streets and beaches, but even if they are disposed of properly, they will spend hundreds of years sitting in landfill sites across Scotland before they even begin to breakdown.
"If we are to seriously tackle the plastic crisis, then we must move away from all single-use items, including masks, to reusable products instead."
Zero Waste Scotland has launched a campaign to address the mounting single-use masks which are blighting the environment.
Emma Leel, litter and fly tipping prevention programme manager at Zero Waste Scotland, said: "Used disposable face coverings cannot be recycled, so they must be placed in the general waste bin.
"Choosing a reusable face covering in the first place is a win-win, as it's better for both purse and planet.
"It is estimated that people could save around £180 per year by switching to reusable face coverings from single-use for daily use.
"If we can avoid the need to pick up a single-use covering at the shops it will mean less litter and fewer problems for local authorities.
Jonathan Ratcliffe from TradeWaste said: "When we think about mask use, we're probably going to be using them for another year or so, and this problem is only going to get worse and worse."