Investment Growth Calculator: a practical guide
What could regular saving and investing add up to?
See what regular monthly saving and an imagined investment return could add up to.
By VolatileShares · Example version 1 · Updated . Hypothetical inputs, not financial recommendations or live company data.
A worked example, in plain English
The idea in 10 seconds: Your pot has two sources: money you add and money the example gains or loses.
Separate what you add from what the model adds.
Returns can fall. This example leaves out tax, fees and rising prices.
- Hypothetical ending balance
- $16,250.76
- Total contributed
- $12,500.00
- Growth / loss
- $3,750.76
Walk me through the full calculation
Starting with $500.00 and adding $100.00 at the end of each month for 10 years, your hypothetical balance would be $16,250.76 if the annual return stayed at 5%.
You contribute $12,500.00 yourself. The other $3,750.76 comes from modeled growth, not money you put in. This assumes a constant rate, not the ups and downs of actual investments, and excludes fees, taxes and inflation.
Inputs used for this example
These are the calculator's example defaults, not suggested amounts or rates. Market calculators initially display USD. Change currency in the toolbar without creating a personal profile. Under optional Location & display settings, choose an example country for its currency and available historical CPI. Review any example household size and rent assumption before explicitly applying local assumptions: matching unedited budget/inflation fields change, while edited or restored inputs are kept. Lifestyle budgets are fictional examples, not measured national averages. Local tax, pension and borrowing links are guidance, not personal calculations. Switching currency alone does not change percentages, ages or share counts.
- Money you start with (USD)
- 500
- Money you add each month (USD)
- 100
- Yearly gain or loss to try (%)
- 5
- How many years?
- 10
Work backwards from your goal
What monthly contribution would reach my goal?
Try 0% growth to see what your own saving does.
Choose Work backwards, enter your target and the few essential inputs, then choose Calculate my goal. The answer is checked with the same forward calculation and applied in one step. Example assumptions are disclosed under More options. Expand Calculation details & tools only if you want more detail. Impossible or out-of-range goals show an error instead of invented numbers. Long numbers display commas while editing; calculations and saved snapshots keep the original precision.
Return to the interactive calculator above →How the calculation works
Monthly rate = (1 + annual return / 100)^(1/12) - 1. Each month: balance = balance x (1 + monthly rate) + contribution.
What this cannot tell you
Constant effective annual return, end-of-month contributions and no withdrawals. Excludes taxes, fees and inflation; returns are not guaranteed.
Changing an assumption changes the example, not the future. Verify source dates and actual product, tax and lending terms before relying on any result. These tools do not replace appropriately qualified advice.
Separate the saving habit from the return assumption
At a 0% return, $100 added each month contributes exactly $12,000 over 10 years. In this model, any amount above your contributions comes from the assumed return, not extra deposits. Fees, taxes and inflation are excluded.
Illustrative arithmetic, not market evidence or a promise of returns.
Keep a useful starting point
In the interactive calculator, compare different assumptions or explicitly save a named snapshot to My browser notebook. Saving is optional and browser-only, not an account or cloud backup. Revisit it on the same browser profile; restoring never refreshes prices or assumptions.