Investment growth (monthly contributions)
Shows lump sum × growth plus an accumulating contribution stream (`pow` + annuity factor)—the kind of multi-term model wealth apps publish. Tune compounding frequency or tax wrappers in Calclet.
Example scenario
A household seeds twelve thousand dollars into a taxable brokerage auto-invest plan while sweeping six hundred fifty dollars each month into the same diversified allocation modeled at seven percent nominal annual return with earnings reinvested monthly over eighteen years—aligned with a kid’s college glide path rather than retirement timing. Systematic contributions alone sum to one hundred forty thousand four hundred dollars excluding the opening lump, while compound growth lifts total projected ending balance toward roughly three hundred twenty-two thousand dollars before inflation adjustment or capital-gains tax drag.
Investment growth (monthly contributions)
Nominal future value — not inflation-adjusted
Want a similar calculator on your website?
Describe your fields and formula in plain English, match your brand, and embed the widget anywhere—WordPress, Webflow, Shopify, or custom HTML. Capture leads when you're ready.
How to project ending balance with lump-sum and monthly investing
- Input starting balance from accounts you intend to keep invested across the horizon—exclude earmarked emergency cash unless it truly compounds alongside contributions.
- Set monthly contribution to autopilot payroll or ACH transfers net of platform minimums—raise the figure when modeling raises rather than keeping static raises implicit.
- Slide assumed annual return to match your portfolio policy statement—lower numbers stress-test conservative glide paths while higher numbers illustrate optimistic upside only.
- Compare estimated ending balance against money added from monthly flows alone—gap highlights compound earnings versus principal funding.
Return and cadence assumptions planners compare against
- Long-run balanced portfolio references
- Academic and industry literature often cites broad-equity long-run nominal returns materially higher than cash while realized paths swing decade to decade—stress-test six-to-eight percent planning bands alongside bear-market sequences
- Contribution discipline
- Automated monthly investing reduces timing risk versus lump-sum speculation—sequence-of-return risk still matters when withdrawals begin even if accumulation math looks smooth
- Nominal versus inflation-adjusted wealth
- This calculator prints nominal ending balances—divide future dollars by assumed CPI growth separately when comparing purchasing power across horizons
Best use cases
- Growth and performance planning
- Budget and forecast scenario modeling
- Client-facing pre-qualification and education
Frequently asked questions
Does this assume contributions deposit at month-end with monthly compounding?
The annuity term matches textbook end-of-month contributions compounded monthly at the stated nominal annual rate—front-loaded paycheck timing shifts outcomes slightly versus this baseline.
Why label ending balance nominal instead of inflation-adjusted?
Because headline brokerage statements quote nominal dollars—subtract expected inflation or convert to today’s purchasing power offline when comparing tuition or retirement targets.
Where do taxes on dividends and capital gains fit?
Outside this formula—tax-advantaged wrappers defer or eliminate many drags while taxable accounts require assumed tax drag layered manually.
Should I model my workplace match inside monthly contribution?
Yes when vesting already cleared—gross up employer deposits that hit your account while remembering matches sometimes vest on graded schedules excluded from naive contribution totals.
Glossary
Scenario modeling
Comparing multiple assumption sets to estimate potential outcomes before execution.
Conversion intent
User behavior that indicates readiness to take a commercial action such as signup or purchase.
Related calculators
Category: Personal finance & accumulation modelingTopics: Compound growth, Monthly contributions, Future value
Last reviewed: 2026-05-07
Reviewed by: Calclet Growth Team