UK dollars are worth less than $1,500 (AU$1,200) and sterling has fallen by more than half in value since the Brexit vote.
But the currency’s recent slide has left it far more attractive to buy than a dollar in any other country.
A new book on currency exchange rates by the Oxford University Centre for Monetary Studies estimates the dollar is now worth about 25 per cent less in value than a pound.
The pound is down by about 5 per cent since June last year, the currency agency said.
In Australia, a new book by The Australian has also calculated the dollar has fallen from about $1.27 to $1 in just two years.
For its part, the Bank of England has warned the pound is in “very strong” demand and it expects to see the pound continue to fall for a long time.
Australia’s currency is pegged to the US dollar, so when the US government moves to devalue the currency it also reduces the value of the Australian dollar.
Since the Brexit referendum, however, the US has begun to devaluing the dollar.
So the British pound has dropped by an even larger amount than in the US.
Why are British dollars so cheap?
A currency exchange rate can make it harder to compare currencies, and there are a number of reasons why the UK dollar is cheaper than other currencies.
One of the big differences between the British and US dollar is that the US dollars are backed by the Federal Reserve, which has the power to raise interest rates to stimulate the economy.
It also makes it easier to buy a British pound than a US dollar.
If the UK government raises interest rates, the pound can fall as a result.
If the rate goes up, the UK can then raise its own interest rate, which will also lower the value and sell the pound.
If a UK government cuts interest rates and the pound falls, that could lead to a drop in demand for the currency, which could reduce the value.
And, if the pound has weakened, the value will drop as a direct result.