Plan Your Investment Growth. Reach Your Financial Goals.
CompoundFX is a compound interest calculator for iPhone that models compound growth, calculates what it takes to reach a financial target, and compares strategies.
iPhone app, iOS 17 or later
Everything You Need to Plan and Grow
The full calculator is free. Pro adds tools for planning toward a goal and weighing one strategy against another.
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Real-time growth chart Free
Your projection updates live, with milestone markers at $100K, $250K, and $1M.
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Year-by-year breakdown Free
See how much you contributed and earned in every year.
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Branded image sharing Free
Share any projection as a branded image to text or social media.
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Goal Mode Pro
Solves for the rate of return, time horizon, starting principal, or monthly contribution you need to reach a goal.
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Side-by-side scenario comparison Pro
Compare plans side by side to see where they differ, the total dollar impact, and when one strategy pulls ahead.
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Two-page PDF reports Pro
Export an executive summary, growth chart, and milestone breakdown as a PDF.
Goal Mode (Pro)
Know Your Goal. Find Your Path.
A standard projection works forward: you enter a starting amount, a rate, and a time frame, and CompoundFX shows where you end up. Goal Mode works backward: you enter the target, and it solves for the rate of return, time horizon, starting principal, or monthly contribution you need to get there.
Worked example
To reach $1,000,000 in 30 years from a $25,000 starting balance, at a 7% annual return, you need to contribute $653.37 a month.
- Required monthly contribution
- $653.37
- Total deposited, including the $25,000 start
- $260,213
- Supplied by compound growth
- $739,787
Assumptions: a constant 7% annual return compounded monthly, deposits at the end of each month, before inflation and taxes. Calculated with this site's shared calculation engine; results in the app change with your settings.
Scenario comparison (Pro)
Compare Strategies Side by Side
Save as many scenarios as you like, then compare them side by side. CompoundFX highlights the variables that differ between your plans, the total dollar impact of those differences, and when one strategy pulls ahead of the other.
More about scenario comparisonBuilt for Real-World Assumptions
Real growth depends on more than one interest rate. These adjustments are all included in the free download.
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Inflation, tax, and expense-ratio adjustments
Adjust projections for inflation, taxes, and fund expense ratios.
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Annual or deferred tax treatment
Choose annual or deferred tax treatment for your projection.
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Custom contribution schedules
Contribute daily, weekly, semimonthly, monthly, or annually.
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Custom compounding intervals
Compound anywhere from daily to annually, including semimonthly.
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Deposit timing
Make deposits at the start or the end of each period.
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Flexible duration
Enter your time horizon in years, months, weeks, or days.
Every projection is an estimate based on the inputs you provide, not a guarantee of actual investment performance.
Your Financial Scenarios Stay Yours.
No accounts, no analytics, no data collection. Everything runs locally on your device.
CompoundFX works fully offline and includes no third-party SDKs. Your saved scenarios stay on your iPhone, and the app's App Store privacy label reads Data Not Collected.
Read the privacy policyFree to Download, Pro When You Need It
Free to download. Optional one-time Pro upgrade. No subscription.
Free
- Full compound interest calculator
- Real-time growth chart
- Year-by-year breakdown
- Inflation, tax, and expense-ratio adjustments
- Annual or deferred tax treatment
- Custom contribution schedules
- Custom compounding intervals
- Deposit timing
- Flexible duration
- Sub-year precision
- Branded image sharing
Pro
Everything in Free, plus:
- Goal Mode
- Unlimited saved scenarios
- Side-by-side scenario comparison
- Two-page PDF reports
Pro supports Family Sharing.
Try the free compound interest calculator.
Run a quick projection in your browser: enter a starting deposit, a monthly contribution, a rate, and a time frame. It is a simpler tool than the app, and it needs no sign-up.
Start Planning with CompoundFX
iPhone app, iOS 17 or later. Free to download. Optional one-time Pro upgrade. No subscription.
