CalculatorsSwitch calculator
How this works
In the 1p challenge you save 1p on day one, 2p on day two and so on, so on day 365 you save £3.65. Each day is just a penny more than the day before.
The calculator adds it up: over d days the total is the daily increase × d × (d + 1) ÷ 2. It also shows the average day and how much falls in each month, which depends on the day you start.
What it assumes
- Counting down from the biggest day saves exactly the same total.
- Interest isn’t included.
- Monthly totals follow the calendar from your start date.
Worked example
A year of pennies from 1 January
- Over 365 days you save £667.95. The last day is £3.65 and the average day is £1.83.
- Starting on 1 January 2027, January adds up to just £4.96, while December takes £108.50.
- In a leap year, 366 days gives £671.61.
- Go up by 2p a day instead and you save £1,335.90.
Worked out with the same maths as the calculator above.
What to do next
Common questions
Why does it feel easy at first and hard later?
The amounts grow every day, so the second half of the year holds about three quarters of the total. Running it in reverse puts the bigger days first instead.
Do I have to save every single day?
No. Many people save once a week by adding up that week’s days. The total is the same.
Is reverse better around Christmas?
Usually. If you start in January and count down, December’s days are the smallest, which helps when spending is highest.
How do I save pennies when I pay by card?
Move the amount by bank transfer, or add up a few days and move them at once. Rounding up to the nearest pound now and then gets you ahead of schedule.