Nearly all the major mortgage lenders in the UK have announced increases in the cost of home loans in recent days.
Analysts are uncertain over whether there are more to come, but are urging people who need to find a new deal to act now.
Someone whose five-year deal is coming to an end faces paying more than £5,000 more a year on their next deal under a typical rate, if they borrow the same amount of money.
Many lenders allow people to lock in a new deal six months before their current one comes to an end, with an opportunity to switch if the costs come down before it kicks in.
"Borrowers expecting mortgage rates to drop in the coming weeks have had their hopes dashed," said Rachel Springall, from financial information service Moneyfacts.
"It is still essential borrowers do not delay seeking advice to navigate the mortgage maze."
How much could my mortgage payments change?
How much are you borrowing?
If you have an existing mortgage enter the outstanding balance left to pay. If not, enter the total you are looking to borrow.
£
How long will you take to pay it back?
If you have an existing mortgage enter the total number of years remaining. If not, enter the total number of years you are looking to borrow over.
years
What is your current...
For those with a mortgage enter the rate for your current fixed term. For those without a mortgage enter an interest rate from another source, such as a bank's mortgage rate calculator.
interest rate
monthly payment
interest rate
%
Choose an interest rate to compare with…
%
At this rate, your payments could change by…
monthly change
to
monthly total
The information you provided on your monthly payments would not be sufficient to pay off your mortgage within the number of years given.
This calculator does not constitute financial advice. It is based on a standard mortgage repayment formula dependent on the mortgage size and length and a fixed interest rate. It should be used as a guide only and does not represent the suitability, eligibility or availability of mortgage offers for users. For exact figures, users will need to approach an official mortgage lender.
Interest rates fluctuate based on the Bank of England's base rate and market conditions
For borrowers, the interest rate on a fixed mortgage does not change until it expires, usually after two or five years, and a new one is chosen to replace it. The vast majority of homeowners and buyers have this kind of mortgage.
Since the Iran war began, global economic uncertainty has pushed up the cost of deals.
Speaking to MPs on the Treasury Committee, Bank of England governor Andrew Bailey said UK borrowers had seen the biggest rise in mortgage rates, apart from Japan, since the conflict started than in other countries in the G7 group of major economic powers.
Someone on a typical two-year deal, and borrowing £250,000 is likely to pay £120 more a month in mortgage repayments than they would have had they secured the deal at the start of March when the US-Israeli strikes began, according to Moneyfacts.
More recently, UK government borrowing costs have been rising, which has a knock-on impact on mortgage rates.
That pressure has been maintained in the latest sale of debt by the UK on Tuesday. A 30-year bond issued by the UK was sold with a yield - or interest rate - of 5.82%, the highest since 1998.
The situation has resulted in several major lenders raising their rates in the last few days.
"The difficult bit is knowing whether this is the end or just the first round of increases," said David Hollingworth, from broker L&C.
Aaron Strutt, of broker Trinity Financial, said: "Hopefully this will be the end of the rate rises for a while, but there are certainly no guarantees.
"Multiple small mortgage price rises add up and ultimately deter people from buying homes."
Potential buyers and borrowers are being urged to seek advice and plan early.
Latest data from the Bank of England shows that more buyers are taking loans with smaller deposits, leaving them more exposed to rate changes.
The proportion of mortgages where the loan is more than 90% of the value of the home has reached its highest level in 18 years.
The latest moves on mortgage rates will be a further blow to those who are coming off much cheaper five-year deals.
However, rates are still some way short of their peaks of recent years, and how much people can borrow, and at what rate, depends considerably on their circumstances.
Moneyfacts said that, as of Tuesday, the average rate on a new, two-year deal was 5.65%. On a five-year product, the average was 5.70%.
Millennials have found it hard to buy homes – but things may be turning a corner
Faisal Islam: Chancellor's attempts to boost vibes may limit tax rises
