A free savings calculator on iPhone lets you project how a starting balance plus regular deposits grows into a future value, with the money you contributed shown separately from the interest earned, all inside your phone's browser without installing a finance app. The tool takes five inputs (starting balance, deposit amount, deposit frequency, annual interest rate, and number of years) and returns three numbers: the projected future value, your total contributions, and the interest earned on top. The starting balance grows by compound interest, and each recurring deposit is treated as the end-of-period contribution in an ordinary annuity, so every new deposit starts earning interest from the moment it lands. Because the calculator lives in a normal web page, it works the same in Safari, Chrome, and any other iPhone browser, recalculates in real time as you type, and sends nothing to a server.
Why Use a Browser-Based Savings Calculator on iPhone
The App Store lists dozens of savings and compound interest calculators, including iPhone-only titles that promise multi-currency support, ETF projections, and colorful charts. Most of them work fine, but they share a few drawbacks worth weighing: you have to download the app, grant it permissions, sometimes create an account, and update it when iOS changes. A browser-based Savings Calculator sidesteps all of that. You open the page in Safari, type your numbers, and watch the future value update as you adjust the deposit amount or the rate. No installation, no sign-up, and nothing about your inputs leaves the device.
For many people the deciding factor is simply having one calculator that matches how a real savings account actually behaves: a starting balance that compounds, plus a stream of deposits that land on a schedule. Some iPhone apps focus on lump-sum compound interest, others on investment portfolios, and a few on retirement income. If your question is the everyday one, "if I keep putting $200 a month into savings at 4%, how much will I have in 10 years?", a recurring-deposit calculator is the right tool.
How to Use the Savings Calculator on iPhone
- Open Safari on your iPhone and load the Savings Calculator page. The interface is a single form, so it fits the iPhone screen without zooming or horizontal scrolling.
- Tap the Starting Balance field and type the amount already in the account today. Use the on-screen number pad.
- Tap Deposit Amount and enter how much you plan to add each period. Leave it at zero to model a single lump sum.
- Tap Deposit Frequency and pick Monthly, Quarterly, or Annually from the menu. This choice changes the periodic rate and the total number of periods the calculator uses internally.
- Tap Annual Interest Rate and enter the rate as a percentage, for example 4.5. Use the rate your bank actually advertises, not a promotional teaser rate.
- Tap Years and enter how long you plan to keep saving. Short horizons suit vacation or emergency funds; long horizons suit a down payment or college fund.
- Read the three output figures: the projected Future Value, the Total Contributions (starting balance plus every deposit), and the Interest Earned (future value minus total contributions).
- To compare scenarios, change any input, for example bump the monthly deposit from $200 to $300, and the three figures update instantly without leaving the page or pressing a separate calculate button.
If you want the calculator one tap away, in Safari tap the Share button, choose Add to Home Screen, and confirm. The page opens full-screen next time like a regular app, but it never asks for updates, notifications, or tracking permissions.
What Each Input Controls
The calculator has five inputs and three outputs, and each input changes the future value in a predictable way. The table below summarizes what each input does and where the right number usually comes from.
| Input | What it controls | Where to find the right value |
|---|---|---|
| Starting Balance | The lump sum already in the account, which compounds on its own. | Your bank's current statement. |
| Deposit Amount | How much you add each period. | Your automatic transfer or budget. |
| Deposit Frequency | How often the deposit lands and interest is added. | Match your real schedule; most automatic transfers are monthly. |
| Annual Interest Rate | The yearly rate the account pays, before compounding. | Your bank's published APY or interest rate. |
| Years | How long the projection covers. | The target date of your savings goal. |
The three outputs are the projected future value, the total contributions (starting balance plus deposit amount times number of periods), and the interest earned, which is the future value minus the contributions. Splitting the final number this way is what makes the tool useful for planning: you immediately see how much of the balance is your own discipline and how much is growth.
How the Math Combines Starting Balance and Recurring Deposits
Under the hood, the calculator combines two standard formulas. Your starting balance grows by compound interest using initial × (1 + i)^N, where i is the periodic rate and N is the total number of periods. Each recurring deposit is treated as an ordinary annuity, added at the end of every period, and grows as contribution × ((1 + i)^N − 1) / i. Adding the two pieces gives the future value. The periodic rate i is the annual rate divided by the number of compounding periods per year, and N is the number of compounding periods per year multiplied by the number of years. This is the standard future-value framework described in the Future value entry on Wikipedia and matches how recurring savings grow in practice, as further explained in the compound interest reference.
When the annual interest rate is 0, the formula collapses to initial + contribution × N: no growth, just arithmetic. Total contributions are simply the starting balance plus every deposit you make, and interest earned is the future value minus total contributions, so you can see exactly how much of the final balance is growth versus money you set aside. If you want the algebra written out for your own numbers, the guide Savings Calculator Formula: Compound Interest + Annuity walks through the substitution step by step.
Worked example you can verify by hand. Starting balance $1,000, monthly deposit $200, annual rate 5%, 10 years. The periodic rate is 0.05 ÷ 12 ≈ 0.004167, and the total number of periods is 120. The starting balance grows to $1,000 × (1.004167)^120 ≈ $1,647. The recurring deposits grow to $200 × ((1.004167)^120 − 1) ÷ 0.004167 ≈ $200 × 155.28 ≈ $31,056. The future value is therefore $1,647 + $31,056 ≈ $32,703. Total contributions are $1,000 + $200 × 120 = $25,000, so interest earned is $32,703 − $25,000 = $7,703. If you plug the same five inputs into the calculator, you will land within a few dollars of those numbers.
How Deposit Frequency Changes the Future Value
Switching from annual to monthly deposits at the same annual rate produces a slightly higher future value, because interest is calculated and added more often. The relationship goes in one direction: more frequent deposits and compounding always beat less frequent ones when the annual rate is positive, but the gap is small for short horizons and modest rates. To feel the gap, enter the same inputs three times in a row and flip the frequency between monthly, quarterly, and annual; the future value moves, and total contributions change too because the number of periods depends on the frequency.
| Deposit Frequency | Periodic Rate (i) | Total Periods (N) for 10 Years | Effect on Future Value |
|---|---|---|---|
| Monthly | Annual rate ÷ 12 | 120 | Highest, because interest is added most often. |
| Quarterly | Annual rate ÷ 4 | 40 | Lower than monthly. |
| Annually | Annual rate | 10 | Lowest, because compounding is applied once a year. |
The values above are the formulas the calculator uses internally, not computed dollar amounts; for the dollar result on your specific inputs, use the tool. Note that the deposit frequency also changes what "deposit amount" means: $200 a month is $600 a quarter and $2,400 a year, so keep the cadence consistent when you compare scenarios.
What This Calculator Doesn't Account For
Because the calculator runs in your iPhone's browser and uses standard formulas, it makes a few simplifying assumptions. Deposits are assumed to arrive at the end of each period, which is the ordinary-annuity convention and is slightly conservative; depositing at the start of each period would earn a little more interest. The interest rate is treated as fixed for the whole horizon, even though real savings rates move with central-bank policy and bank pricing decisions. Account fees, taxes on interest income, minimum-balance requirements, and promotional teaser rates are not modeled. Treat the future value as a planning estimate, not a guarantee, and verify any decision based on it with a licensed professional.
For questions the savings calculator is not built for, the growth of a single lump sum, the erosion of buying power by inflation, or how long it takes to pay off a debt, other calculators on the site handle those directly. The compound-interest math the savings calculator relies on is the same math those tools build on, but the inputs and outputs differ.
Related reading: Loan Payoff Calculator on iPhone: Run It Free in Safari.