An investigation by the BBC and Zoopla shows a sharp drop in the volume of available rental units in the past 18 months.
Lettings agencies typically have 10 rentals compared to over 16 before September 2021, according to figures shared with the BBC by Zoopla.
It suggests that the number of rental properties UK hasn't fallen but has remained roughly static since 2016 - but demand for rented accommodation has risen to more than 50 percent above normal levels, Zoopla's figures show which is pushing rents and yields higher.
The portal draws its information from listings on its website, which covers 85 percent of UK properties listed for rent. Existing tenants, aware of the shortage, choose not to move, the portal says.
"We've seen a big increase in demand for rented housing from record high immigration, the economy reopening [after the pandemic]" states Richard Donnell, executive director for research at Zoopla.
"But at the same time, we just haven't seen much new investment by landlords in rented housing. And that's creating a real crunch in availability."
The BBC investigation says some landlords are leaving the market and cashing in - 11 percent of homes for sale on Zoopla were previously rented. For others, short-term lets such as holiday lets or Airbnb offer better returns than long-term tenants. Zoopla has seen a three-fold increase in short-term lets since 2019.