Premium Bond Calculator

supersteamer

Has the Premium Bonds Odds Calculator gone a bit wrong or am I just misunderstanding it?

Just for fun, I tried to see what odds I had of winning £1 million over 1..5 years if I put in 50k, and it came back with:

1 1 in 5,747

2 1 in 46,994

3 1 in 1,290

4 36.8%

5 45.6%

I'm no statistician, but that doesn't look anywhere close to right!   Why would my odds be far worse after 2 years than 1 year?   NS&I would be very quickly broke if there was a 45.6% change of winning after 5 years!

Even better, if I take out £2000, I see that I have odds of winning £1 million of 51.8% after investing 48k for 5 years.    So better odds with less money and more likely to win the jackpot than not!  

grumbler

What calculator and what's "1 1 ", "2 1" etc.?

https://www.moneysavingexpert.com/savings/premium-bonds-calculator/ for £1M, £50K and 1.5 years shows: "You are lucky - only 0.452% of people who have put £50,000 in premium bonds over 1 year 6 months win more than £1000000"

eskbanker

Yes, looks broken to me!

On the basis that there are roughly 120bn bonds in each draw (helpfully for round numbers!) and two £1m prizes, an individual bond has 1 in 60bn chance of winning £1m in a month, and so about 12 in 60bn chance in a year, so 50K bonds roughly 600k in 60bn or 1 in 100,000.

It's not exact but 2 years would therefore be about 2 in 100,000 and so on....

supersteamer

Sorry, that could have been better formatted....

Yes, it's the calculator on this site which you've linked to.  My output were taken from the "Full breakdown of your prize-winning chances"

Bonds: £50,000
Over What Time?

1 year:  1 in 5,747

2 year:  1 in 46,994

3 year:  1 in 1,290

4 year:  36.8%

5 year:  45.6%

grumbler

I don't understand what you are doing

For "How lucky am I" I don't see "Full breakdown of your prize-winning chances" option.

For "What will I win?" with £50K and 1.5years I see the breakdown, but by winnings, not years:

At least £1,000	99.6%
At least £1,500	87.1%
At least £2,500	18.8%
At least £5,000	2.00%
At least £10,000	1.16%
At least £25,000	1 in 134
At least £50,000	1 in 173
At least £100,000	1 in 203
At least £1,000,000	1 in 221

eskbanker

grumbler said:

I don't understand what you are doing

For "How lucky am I" I don't see "Full breakdown of your prize-winning chances" option.

For "What will I win?" with £50K and 1.5years I see the breakdown, but by winnings, not years:

At least £1,000	99.6%
At least £1,500	87.1%
At least £2,500	18.8%
At least £5,000	2.00%
At least £10,000	1.16%
At least £25,000	1 in 134
At least £50,000	1 in 173
At least £100,000	1 in 203
At least £1,000,000	1 in 221

OP is trying to establish the odds of winning £1m from a maximum holding over 1 year, 2 years, etc, up to 5 years (i.e. five separate answers):

supersteamer said:

Just for fun, I tried to see what odds I had of winning £1 million over 1..5 years if I put in 50k

but the calculator is spewing out nonsensical figures, as both of you have demonstrated!

supersteamer

I've run it 5 times (1 year ... 5 years) and am just looking at the last row of the output in each case (At least £1,000,000):

For "Over What time?" 1 Year

At least £1,000,000

1 in 5,747

For "Over What time?" 2 Years

At least £1,000,000

1 in 46,994

For "Over What time?" 3 Years

At least £1,000,000

1 in 1,290

For "Over What time?" 4 Years

At least £1,000,000

36.8%

For "Over What time?" 5 Years

At least £1,000,000

45.6%

supersteamer

eskbanker said:

but the calculator is spewing out nonsensical figures, as both of you have demonstrated!

Thanks for confirming.  It's a pity - I was already planning my mansion...

Who do I ask to fix it?

grumbler

Yes, I see now - nice pictures, but absolute nonsense.

And for "What will I win?" with £50K

1 year      - At least £1,000,000  1 in 5,747

1.5 years - At least £1,000,000  1 in 221

2   years -  At least £1,000,000  1 in 46,994

1.5 seems to be the optimal term. LOL

grumbler

I reported the problem, but there is a special thread for discussing this calculator - Discuss tool

eskbanker

supersteamer said:

eskbanker said:

but the calculator is spewing out nonsensical figures, as both of you have demonstrated!

Thanks for confirming.  It's a pity - I was already planning my mansion...

Who do I ask to fix it?

https://www.moneysavingexpert.com/site/site-contacts/ has some email addresses, including:

Spotted an error, broken link or technical problem in an article or guide?
Tell us about the problem at brokenlink@moneysavingexpert.com  

[...]

Not sure who to contact?
Please email furtherhelp@moneysavingexpert.com and our team will aim to help as much as possible.

Ignore all that, correct answer given below by @grumbler!