Stable Numbers
Compound Interest Calculator
Model savings growth with compound interest and monthly contributions. See final balance, total paid in, and interest earned. Share your setup or download a CSV.
Applied each month at the timing you choose below.
Nominal APR, compounded monthly.
You can mix years and months.
Start of month compounds contributions for that month. End of month adds after interest.
Optional increase to your monthly amount each year.
Used for month labels in the schedule.
Monthly compounding. Contributions applied at your chosen timing. Annual uplift increases the monthly amount on each anniversary.
Show monthly schedule
| # | Date | Start balance | Contribution | Interest | End balance |
|---|---|---|---|---|---|
Values rounded to two decimals for display. Minor rounding differences can occur.
About this calculator
The balance grows through monthly compounding. If you choose start of month timing, the monthly contribution is added before interest for that month, which gives a slightly higher outcome than end of month where interest is applied first. An optional annual uplift increases your monthly contribution on each anniversary which mirrors common savings habits.
The schedule shows month-by-month progression so you can see how contributions and interest interact. Use this for ISA planning, emergency funds or long term goals. Treat results as guidance, as banks may compound using slightly different timetables.
Explore more in the finance tools hub.