Choose the wrong PIN code and a criminal who has stolen your card will be able to simply guess your code - allowing them instant access to your money.
Analysis of 3.4 million real PIN codes found that people are surprisingly predictable - with a “top ten” of most-used codes which allow thieves an easy “way in”.
Almost 11% of the passwords analysed use the code 1234. For a thief or hacker, it's a gift - giving them a one in ten chance to unlock a stolen card on the first guess.
The report by Data Genetics was analysed by America’s Yahoo! Sideshow this week - and found that the least-used code was 8068.
“As noted above, the more popular password selections dominate the frequency tables. The most popular PIN code of 1234 is more popular than the lowest 4,200 codes combined!
That's right, you might be able to crack over 10% of all codes with one guess! Expanding this, you could get 20% by using just five numbers!”
[Related: Tablet computer ownership trebles]
The research analysed 3.4 million leaked four digit passwords to find the least - and most - common.
Nearly a third of passwords - 28.3% - can be guessed using just 20 combinations.
More than 6% of people use 1111, which also provides thieves with a good 'second guess'. Another 2% choose 0000.
As well as single-number combinations such as 5555 and 9999, simple variations such as 1122 are also common.
'James Bond fans may be interested to know 0007 is found at position 23,' say the researchers.
Of the 3.4 million passwords analysed, 8068 was the least-used combination - but, the researchers warn, 'Hackers can read too.' In the wake of the research, it’s now likely that 8068 will be far less secure.
'If you are a consumer and your recognize any of the numbers to be your passwords/pins I hope you apply common sense and immediately change them to something a little less predictable,' writes the Data Genetics researcher.
'Alternatively, you could be lazy and not change things (In that case, at least the only person you are harming with this apathy is yourself.)'
The most commonly used PINS are below: