PangPang ToolsPrincipal 1,000; annual rate 10%; 2 years; annually
Final balance 1,210.00; interest 210.00The first year earns 100; the second earns 110 because the first year’s interest is reinvested.
Finance & Tax
Compound interest calculator
About this tool
Explore how reinvesting interest changes a single initial amount over time. Compare annual, semiannual, quarterly, monthly and daily compounding at the same nominal annual rate. The result separates the initial principal from the modeled interest earned, without assuming future returns are guaranteed.
Savings & compound growth
Choose a task. Inputs stay in this page only.
Monthly deposits and lump-sum growth are calculated separately. Lump-sum terms use whole years; only complete years transfer from monthly savings.
MAKE IT SIMPLE
Result
Yearly compound growth
Amounts display two decimals. Calculations use unrounded values, so displayed rows may not add up exactly. Download all rows as CSV.
| Year | Opening balance | Interest earned | Closing balance |
|---|
Worked examples
Principal 1,000; annual rate 0%; 5 years; monthly
Final balance 1,000.00Changing compounding frequency has no effect at a zero rate.
Questions & answers
What is the difference between nominal and effective annual rates?
The nominal rate is divided by the number of periods. At a positive rate, reinvesting during the year produces an effective annual rate of (1 + i/m)^m − 1, which is higher than i when m is greater than one.
Can I include monthly deposits?
No. This tool models one initial amount only. Regular deposits need a separate cash-flow model with deposit timing assumptions.
MAKE IT SIMPLE
Result
Monthly savings schedule
Amounts display two decimals. Calculations use unrounded values, so displayed rows may not add up exactly. Download all rows as CSV.
| Month | Opening balance | Deposit | Interest | Closing balance |
|---|
Worked examples
Initial 0; monthly 100; annual 12%; 2 months; month-end
Final 201; principal 200; interest 1Month one ends at 100. Month two earns 1 interest on the opening 100 and adds another 100.
MAKE IT SIMPLE
Result
Worked examples
Target 1,400; existing balance 200; interest 0%; deadline 12 months
Required monthly deposit 100; contributed principal 1,400; projected balance 1,400With no growth, the 1,200 gap is filled by twelve equal month-end deposits of 100.
Target 1,200; existing balance 0; annual interest 6%; deadline 12 months
Required monthly deposit 97.28; contributed principal 1,167.36; projected balance about 1,200.00At an assumed monthly rate of 0.5%, each deposit earns interest until the deadline. Rounding the deposit upward slightly exceeds the target.
Questions & answers
Why can the projected balance be slightly above my target?
The monthly deposit is rounded upward to the nearest 0.01 to avoid falling short. With positive interest, that can make the final projection slightly higher than the chosen goal.
Does the estimate include savings-account tax or changing rates?
No. It assumes one constant nominal annual rate, monthly compounding and month-end deposits. Compare actual product conditions, taxes and fees before deciding how much to set aside.