More than two thirds (68%) of homeowners received the money as a gift not to be paid back.
The average amount required was £17,900 compared to the average first-timer deposit of just under £25,000, meaning parents would contribute 71.6% of the deposit.
Miguel Sard, head of Santander Mortgages, said: “Raising a deposit can be a huge challenge and our research shows that many rely on financial help from their parents in order to get a foot onto the property ladder.
“Buying your first home can be a daunting but there are ways to make it easier and support is available to help first-time buyers with upfront costs.
“The mortgage market is still competitive, with options available to suit most budgets. Our range of Help to Buy mortgages offer competitive fixed and tracker rates to buyers with a 5% deposit and our 1I2I3 Current Account also gives 1% cash back on mortgage payments.”
Nearly three in 10 (29%) received the money as an interest-free loan, while just 3% of parents contributed towards the deposit as an investment.
Even for parents who are yet to become homeowners themselves a third (34%) said they would make a contribution towards their child’s deposit.
Almost three quarters (72%) of females were granted money by their parents compared to 62% of men.
Santander’s Help to Buy: mortgage guarantee products are 2-year tracker at 4.99%, 2-year fixed at 5.49% and a 5-year fix at 5.49%, all without an initial fee.
All products come with the Homebuyer Solution, which includes a free valuation plus £250 cashback.