See balances grow across months, quarters, or years. Add recurring contributions and annual step-ups fast. Get clear totals, interest earned, and exports instantly here.
| Scenario | Principal | Rate | Years | Contribution | Frequency | Compounding | Estimated Ending* |
|---|---|---|---|---|---|---|---|
| Lump sum | $10,000 | 8% | 10 | $0 | — | Monthly | $21,900 |
| Monthly saver | $5,000 | 7% | 15 | $200 | Monthly | Monthly | $74,000 |
| Step-up deposits | $2,000 | 9% | 20 | $150 | Monthly (+5% yearly) | Monthly | $110,000 |
For a fixed rate and fixed compounding, a lump sum grows as: FV = P × (1 + r/n)n·t, where P is principal, r is annual rate (decimal), n is compounds per year, and t is years.
With regular contributions, a common closed-form approximation is: FV = P(1 + r/n)n·t + PMT × (( (1 + r/n)n·t − 1 ) / (r/n)), and if contributions happen at the beginning of each period, multiply the PMT term by (1 + r/n).
This calculator uses a period-by-period schedule to support taxes, step-ups, rate changes, and timing options. Each month, it applies an effective monthly rate derived from your chosen compounding.
Compounding controls how often interest is added to the balance. With the same nominal annual rate, more frequent compounding produces a slightly higher effective return because interest begins earning interest sooner. For example, at 10% nominal, annual compounding yields about 10.00% effective, while monthly compounding is about 10.47% effective. Over 20 years, even a small effective-rate difference can compound into a noticeable gap in the final balance, especially when paired with recurring deposits. Use the same horizon and deposits when comparing frequencies for a fair test.
Contributions usually drive long-term results more than small compounding differences. A monthly deposit increases the invested base, which increases future interest. Timing matters: beginning-of-period deposits earn one extra period of growth versus end-of-period deposits. In a 15‑year plan with steady deposits, switching timing can add roughly one contribution’s worth of extra compounding, especially at higher rates. A 3% yearly step-up often offsets inflation and increases total invested capital.
Many savers increase deposits as income rises. The annual contribution change feature applies a yearly percentage step-up to your deposit amount, which can materially shift outcomes. The annual rate change input lets you test gradual rate drift, such as a laddered portfolio or changing market conditions. A small 0.25 percentage‑point change per year accumulates into meaningfully different schedules over long horizons.
Taxes reduce growth because they remove a portion of earned interest. This calculator applies tax only to positive interest for each period, then compounds the remaining net interest. Inflation is shown through a “real” ending balance, discounting the nominal result by your chosen inflation rate. Comparing nominal and real values helps you judge purchasing power, not just account balance. Inflation inputs help compare purchasing power.
The schedule breaks results into periods, showing starting balance, contribution, gross interest, tax, net interest, and ending balance. Use the monthly view for audits and cash‑flow planning, or yearly view for faster comparisons between scenarios. Export CSV for spreadsheets and budgeting, and export PDF for sharing a consistent, print‑ready summary with stakeholders.
It is the stated yearly rate before compounding adjustments. The calculator converts it into an effective monthly rate based on your selected compounding frequency.
Closed-form formulas assume constant rates and uniform deposits. This tool uses a period-by-period schedule to support taxes, deposit timing, step-ups, and rate changes.
Yes. Total Contributed includes the starting principal plus all recurring contributions added over time, matching what you actually put into the account.
Tax is calculated on positive interest earned in each period, then subtracted from gross interest to get net interest, which is the amount compounded forward.
It estimates the ending value in today’s purchasing power by discounting the nominal ending balance using your inflation rate across the full time horizon.
Use monthly for detailed tracking and verifying assumptions. Use yearly for a compact overview that is easier to compare across multiple what‑if scenarios.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.