We use an average balance calculation to work out the number of entries you get in a Prize Savings Account draw. 

We use this system to keep things fair and reward people who keep money in the account for a long time.   

This article explains average balance in considerable detail including many examples and fully breaking down the calculations themselves, but the important things to take away are:

• The earlier you deposit in the month the more entries you get.
• In the month after you deposit, every £10 of your balance will always = one entry in the draw (provided you don’t withdraw).
• Use the entry calculator on the Prize Savings Account webpage to see how many entries you’ll get if you deposit today.

How much do you need to deposit on a given day to get one entry?

One entry = one full £10 of average balance. 

But note, due to the average balance calculation the amount you need to deposit to get one new entry on a given day slowly increases from £10 throughout the month to a maximum of £310 (but note the exact amount depends on the number of days in the month, i.e. whether there are ; 28, 29, 30, or 31 days in the month).

How much do you need to deposit on a given day to qualify for the draw?

‍You have to hold a minimum average balance of £100 on the last day of the month to be entered into the draw. 

Note: we are changing the minimum average balance from £100 to £10 from 1 December 2025. 

Again, due to the average balance calculation, the amount you need to deposit on a given day to gain a £100 minimum average balance within the same month steadily increases from £100 throughout the month to a maximum of £3,100.

Again, please see the entry calculator on the Prize Savings Account webpage to see how many entries you’ll get if you deposit today and if you’d qualify to enter. 

How is your average balance calculated? 

Your average balance is calculated using the formula below. 

Average balance  = ([# days in month with £𝑥 balance] × [£𝑥 balance]) ÷ [# days in month]

‍Example 1: depositing on the first day of the month
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• You deposit £1,000 on the first day of the month;
• hold it for the entire month;
• don’t deposit further;
• your average balance for the month is £1,000;
  
  • (30 x £1,000)/30 = £1,000
• so, you will get 100 entries in that month’s draw; 
  
  • £1,000/10 = 100 (rounded down to nearest whole number).

Example 2: depositing mid month

• You deposit £1,000 on the 15th day of the month;
• hold it for the remainder of the month;
• don’t deposit further;
• Your average balance is based on:
  
  • 14 days of zero balance, and 
  • 16 days of £1,000;
• your average balance for the month is £533.33;
  
  • (16 x £1,000)/30 =  £533.33;
• so, you will get 53 entries in that month’s draw;
  
  • £533.33/10 = 53 (rounded down to nearest whole number).

Example 3: depositing on the last day of the month

• You deposit £1,000 on the last day of the month;
• Your average balance is based on:
  
  • 29 days of zero balance, and; 
  • 1 day of £1,000;
• your average balance for the month is £33.33;
  
  • (1 x £1,000)/30 =  £33.33;
• so, you will get 0 entries in that month’s draw as your average balance is under £100;
• but with the new minimum elgibility rules from December 2025 onwards you would get 3 entries;
  
  • £33/10 = 3 (rounded down to nearest whole number).

However, in all of the examples above, you would get 100 entries in the following month’s draw. 
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What if I make multiple deposits across the month?

If you make multiple deposits across the month then your average balance will be calculated based on the day of each given deposit. 

For example if you deposit… 

• £1,000 on the 1st (31 days left)
• £50 on the 9th (22 days left)
• £500 on the 16th (15 days left)

You would get 127 entries in total this month from £1,277.42 average balance, based on:

• 100 entries from your £1,000 deposit on the 1st
  
  • (£1,000 x 31) / 31 = £1,000 average balance
  • £1,000 / 10 = 10 whole entries
• 3 entries from your £50 deposit on the 9th
  
  • (£50 x 22) / 31 = £35.48
  • £35.48 / 10 = 3 whole entries
• 24 entries from your £500 deposit on the 16th
  
  • (£500 x 15) / 31 = £241.94
  • £241.94 / 10 = 24 whole entries

The following month you would have 155 entries based on £1,550 total balance (assuming you don't withdraw).

‍Why do we use average balance to calculate entries?

‍We understand that this might sound complicated, but we designed the account to operate in this way to make it fair for everyone (i.e. stop people who simply deposit big sums of money on the last day of the month having an unfair advantage).

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