Bonus Saver Account Calculator: Formula, Example and What the Result Means
Shows interest earned on a bonus saver account when you miss some months. This guide walks through what each input means, the formula behind the answer and a worked example using typical Australian figures. You can follow along in the free Bonus Saver Account Calculator.
Why it matters
Australians save and invest through bank accounts, term deposits, shares, ETFs and property. Interest and dividends are taxable, franking credits can offset tax on dividends, and inflation steadily reduces the value of money that isn’t growing.
What you need to enter
The calculator asks for 4 inputs. The table shows each one with the example value used later in this guide.
| Input | Example value |
|---|---|
| Balance ($) | 10000 |
| Base rate (%) | 1.5 |
| Bonus rate (%) | 3.5 |
| Months bonus conditions met (of 12) | 10 |
The formula
Each month earns the base rate, plus the bonus rate only in months where you meet the conditions.
Worked example
Entering the example values above gives these results:
| Result | Value |
|---|---|
| Interest earned in a year | $450.64 |
| Effective rate achieved | 4.51% |
The headline figure is $450.64 (interest earned in a year). Change any input in the calculator and every result updates instantly, so you can test different scenarios side by side.
How the interest earned in a year changes with balance
The table below keeps every other input at the example value and moves only “Balance ($)” up and down by 10% and 20%. It shows how sensitive the interest earned in a year is to that one figure.
| Balance ($) | Interest earned in a year |
|---|---|
| 8,000 | $360.52 |
| 9,000 | $405.58 |
| 10,000 | $450.64 |
| 11,000 | $495.71 |
| 12,000 | $540.77 |
At 8,000 the result is $360.52; at 12,000 it is $540.77. If a small change in this input moves the answer a lot, it is worth double-checking that figure before you rely on the result.
A practical tip
Most bonus conditions need a deposit and no withdrawals. One missed month can cost most of that month’s interest.
Keep going
Before relying on the number, read Bonus Saver Account: What to Check Before You Trust the Number. You might also find these guides useful:
- Using a Net Worth Calculator in Australia: A Step-by-Step Guide
- Using a Compound Interest Calculator in Australia: A Step-by-Step Guide
- Savings Goal Calculator Explained for Australians
Frequently asked questions
- Are investment returns guaranteed?
- Only some products, such as term deposits, have fixed rates. Share and fund returns vary and can be negative.
- Is my bank deposit protected?
- The Financial Claims Scheme guarantees deposits up to $250,000 per account holder per authorised bank.
- Is this investment advice?
- No. The calculators provide general information only.
Run your own numbers in the Bonus Saver Account Calculator.
Open the calculatorGeneral information only. Rates and thresholds change, usually on 1 July. Confirm current figures with the ATO or the relevant authority, and get personal advice for decisions about your situation.