CompoundFX Support

Get help with CompoundFX, the compound interest calculator for iPhone. For anything this page doesn't cover, email support@originsoftware.net.

Quick answers are in the CompoundFX questions on the FAQ, and the changelog lists what changed in each version.

Getting Started

Install CompoundFX

CompoundFX is free on the App Store for iPhone with iOS 17 or later. There is no account to create: open the app and start a calculation.

Create a calculation

A calculation starts from a few inputs: a starting principal, an interest rate, a deposit amount and schedule, and a duration. As you enter them, CompoundFX updates the projected balance, a real-time growth chart with milestone markers at $100K, $250K, and $1M, and a year-by-year breakdown of what you contributed and what you earned. The full calculator is free.

Understand the inputs

Principal: The amount you start with.
Interest rate: The annual rate of return you expect. The projection applies it at a fixed rate for the whole duration.
Deposits: An amount you add on a schedule: daily, weekly, semimonthly, monthly, or annually. Deposit amounts keep cents.
Deposit timing: Whether each deposit lands at the start or the end of its period. A deposit made at the start has that whole period to earn interest.
Duration: How long the plan runs, in years, months, weeks, or days, with sub-year precision for plans shorter than a year.
Compounding interval: How often interest is added to the balance, anywhere from daily to annually, including semimonthly.
Inflation, tax, and expense ratio: Adjustments that account for rising prices, taxes on growth, and fund fees.
Tax treatment: Annual or Deferred, to match how your account is taxed.

The formula page explains how principal, rate, compounding, and time combine.

Use Goal Mode (Pro)

Goal Mode works backward from a target amount. Instead of projecting where your inputs lead, it solves for the one value you need to reach the goal: the rate of return, the time horizon, the starting principal, or the monthly contribution. The Goal Mode page walks through worked examples of each.

Working with Scenarios

Save scenarios (Pro)

Pro saves unlimited scenarios, so you can keep each plan and come back to it anytime.

Compare scenarios (Pro)

Pro compares saved scenarios side by side. The comparison highlights every variable that differs between your plans (such as inflation, taxes, fees, compounding frequency, and deposit timing), the total dollar impact, and when one strategy pulls ahead. See scenario comparison for an example.

Manage saved scenarios

Saved scenarios live on your iPhone. CompoundFX has no accounts and no server, so there is no online copy to sign in to: everything runs locally on your device. For help organizing your saved plans, email support@originsoftware.net.

Purchases

Free vs Pro

CompoundFX is free to download, including the full calculation engine, real-time growth charts with milestone markers, year-by-year breakdowns, inflation and tax adjustments, custom contribution schedules, and branded image sharing. An optional one-time Pro purchase adds Goal Mode, unlimited saved scenarios, side-by-side scenario comparisons, and two-page PDF reports. No subscription, no accounts, no data collection. Everything runs locally on your device.

Compare Free and Pro feature by feature.

Upgrade to Pro

Pro is a one-time in-app purchase: you buy it inside CompoundFX through the App Store with your Apple Account, and there is no subscription. Pro includes every free feature. Pro supports Family Sharing, so members of your Apple Family Sharing group can use it on their own iPhones without buying it again.

Restore purchases

If you reinstall CompoundFX or move to a new iPhone, use the Restore Purchases control in the app to bring Pro back at no charge. Restoring works when the App Store is signed in with the same Apple Account you bought Pro with. If Pro still doesn't appear, check which Apple Account the App Store is using, then email support@originsoftware.net.

Troubleshooting

Calculation assumptions

CompoundFX projects growth at the fixed rate you enter, compounded at the interval you choose, with deposits on your schedule and timing. Real investments don't return a fixed rate every year, so every result is a projection based on your inputs, not a guarantee of actual performance.

Results look different than expected

Check the duration unit. A duration of 30 months is two and a half years, not 30 years.
Check deposit timing. Deposits at the start of each period earn more than deposits at the end.
Check the compounding interval and the deposit frequency. They are separate settings, and either one changes the result.
Check the adjustments. Inflation, tax, and expense-ratio settings all lower the projection, and an inflation-adjusted figure shows the balance in today's dollars.

The free web calculator on this site compounds monthly, adds contributions at the end of each month, and applies no tax or inflation adjustments. Use the same settings in CompoundFX to compare the two.

Exporting and sharing

Branded image sharing is free: share any projection as an image to text or social media. Two-page PDF reports, with an executive summary, growth chart, and milestone breakdown, are part of Pro. If Pro features are missing after a reinstall, restore your purchase first.

Supported iOS versions

CompoundFX requires an iPhone running iOS 17 or later. To see your version, open the iPhone Settings app and go to General, then About. iOS updates are under General, then Software Update.

Contact Support

Email support@originsoftware.net for help with CompoundFX. Include your iPhone model, your iOS version, and the inputs you used, so we can reproduce what you see.