Is this the right tool?
- Best for
- A year-by-year investment scenario that separates cash contributed from growth under one constant return assumption.
- Choose another tool when
- Use Compound Interest Calculator to compare compounding frequency, or Retirement Calculator when age, inflation-adjusted income, and contribution increases matter.
Decision context
Keep deposits and uncertain growth separate
A future-value total combines money you add with market-dependent growth. Separating them keeps the planning conversation honest.
The contributions line is the part of the projection funded directly by deposits; the growth line depends on the return assumption.
More time changes the model
A longer horizon gives both contributions and assumed returns more periods to compound.
Fees and taxes are outside the model
The displayed return is not reduced for account expenses, fund costs, capital-gains taxes, or withdrawal rules.
Illustrative scenario
An investor compares increasing a contribution by $50 with assuming a one-point higher return. The two changes affect the projection differently, and only the contribution change is directly controllable.
Method notes and further reading
Investment Calculator links these resources for keep deposits and uncertain growth separate. Use the original material when a decision depends on a current rule, a personal circumstance, or a professional standard.
- Investor.gov, U.S. Securities and Exchange Commission: Financial tools and compound interest calculatorMethod reference. General compound-interest and savings education. ArithPilot does not fetch market returns or predict investment performance.Reviewed July 2026.
What this calculator does
It compounds a starting balance and periodic contributions, then reports future value, deposits, and modeled growth. The table makes the long-horizon assumption visible year by year.
When to use it
Use it when comparing a higher monthly contribution with a longer horizon, or when teaching the difference between saving more and assuming a higher return.
Inputs explained
- Initial investment: the starting invested balance.
- Monthly contribution: the recurring amount added each month.
- Annual return: the yearly growth assumption used in the projection.
- Years: the projection horizon used for contributions and the assumed return.
Formula or method
The calculator applies the selected annual return over monthly periods and adds the recurring contribution. It assumes a constant return, regular contribution timing, and no taxes, fees, or withdrawals.
Worked example
Compare a baseline run with a lower return rather than changing every input together. That separates a savings decision from an investment-performance assumption.
How to interpret the result
The growth portion is hypothetical. Actual investments can lose value, vary year to year, carry fees and tax consequences, and may not be appropriate for every horizon or objective.
Practical checks before using the result
- Use a contribution amount that can continue through a setback; a projection is less useful if it assumes deposits that are unlikely to occur.
- Consider inflation separately when the goal is future spending rather than simply a nominal account balance.
Common mistakes
- Reading a modeled average return as a guaranteed annual result.
- Forgetting that tax treatment and investment fees can materially change net outcomes.
Limitations and disclaimers
These results are general estimates only and are not financial, tax, or legal advice. They do not include live lender, payroll, tax-authority, market, contract, fee, insurance, or jurisdiction-specific data.
Related calculator context
Use Compound Interest for another compounding view and Inflation Calculator to translate a future nominal total into a purchasing-power scenario.
Related glossary terms
These plain-English definitions can help you check the terms used in this calculator before relying on the result.
Frequently Asked Questions
Why should deposits and modeled investment growth be read separately?
A longer horizon gives both contributions and assumed returns more periods to compound. The growth portion is hypothetical. Actual investments can lose value, vary year to year, carry fees and tax consequences, and may not be appropriate for every horizon or objective.
How should I test the return and contribution assumptions?
Use a contribution amount that can continue through a setback; a projection is less useful if it assumes deposits that are unlikely to occur. Consider inflation separately when the goal is future spending rather than simply a nominal account balance.
Which investment costs and market risks are outside this projection?
These results are general estimates only and are not financial, tax, or legal advice. They do not include live lender, payroll, tax-authority, market, contract, fee, insurance, or jurisdiction-specific data.