Compound interest calculator
See your future balance and interest earned.
Example plan · try your own numbers
Your projected balance
Enter your numbers to see the possibilities.
Growth chart & what-if
Save, export & assumptions
Estimates only. Assumes unchanged rates, no withdrawals, tax or fees. Monthly approximation; your bank’s daily calculation and product rules may differ. Calculation details →
See the numbers behind the picture
Money in pictures
How does interest grow?
Interest is money the bank pays you for keeping savings in an account.
Made-up example: 10% a year. This is not a bank offer.
1 Put $100 in savings.
You put your money in the account. For this example, leave it there for a year.
2 The bank adds $10.
At 10%, your $100 earns $10 in one year. Keep that $10 in the account.
3 Next year, you earn $11.
Your first $100 earns $10. Last year’s $10 earns $1 more. Together, that is $11.
About this example
The example adds 10% once a year. No deposits, withdrawals, tax or fees. Real savings rates can change. The coins are pictures, not a count of dollars.
QUICK ANSWERS
Questions about your savings?
Choose a question. Get a plain-English answer and a useful next step.
5 questions to explore.
Answers are written in advance. Your search stays in your browser.
SavingsWhat is compound interest?
When interest is added to your savings, that interest can earn interest too. The result depends on your balance, rate, time and deposits; a projection assumes the inputs hold.
Try the compound interest calculatorSavingsWill I always earn the advertised savings rate?
A bonus rate may depend on deposits, balance changes or other account conditions. A welcome rate lasts only for its stated period, so check the ongoing rate, fees and current provider terms as well.
Compare rate conditions in a worked exampleSavingsAre the bank rates on Howloop live?
The bank explorer uses dated snapshots of public product data. Check each product’s retrieval date and confirm the current offer with the provider; the listing does not assess whether you qualify.
Explore the dated savings productsSavingsHow much do I need to save each month?
Enter your target, starting savings and timeframe in the savings-goal calculator. It estimates the end-of-month contribution using a constant rate; try a lower rate too, and include costs that your target needs to cover.
For exampleAt zero interest, a hypothetical $6,000 gap over 12 months needs $500 each month.
Calculate a monthly savings goalSavingsHow do I set an emergency-fund target?
Add up essential monthly expenses and choose how many months you want covered. Use your own bills and income circumstances; the calculator’s example is a starting point for comparison, not a personal recommendation.
Build an emergency-fund estimateNo questions match this search. Try a shorter word, or choose Show all to see every question.
More examples & how the maths works
Your numbers, in real life
A bigger advertised rate can earn less.
Start with $20,000 and add $200 at the end of each month. Compare three fictional accounts over one year.
Estimated interest earned · before tax and fees
- 5% bonus offer
- $821
- 5.5% welcome offer
- $890
- 4.2% steady rate
- $903
0.5% in the final 3 months when conditions are missed.
5.5% for 4 months, then 3.5% for 8 months.
Same illustrative rate for all 12 months.
Compare the money earned across your whole timeframe, not just the number on an advertisement.
Monthly compounding; no withdrawals. All rates are hypothetical and are not forecasts or bank offers.
Try the rate reality checkLet time work with your savings.
A savings balance has three building blocks: the money you start with, the deposits you add and the interest your account earns. Change one input at a time to see which part has the biggest effect on your plan.
How the calculation works
We add interest to the opening balance each month, then add your monthly contribution. Weekly contributions use 52 payments a year and fortnightly contributions use 26, spread across 12 months. The annual table separates your deposits from interest.
Common questions
A few good questions.
Are the bank rates live?
The bank picker uses dated snapshots of public CDR product data. Each product shows when we retrieved it. Rates can change after that date; check the provider before making a decision.
Does the calculator include bonus interest?
The picker starts with a supported base rate. For supported bonus or introductory offers, you can check the published conditions and explicitly choose a conditional scenario. It assumes you meet those conditions; it does not assess eligibility. Supported welcome rates end after their stated period, then return to the base rate. Unsupported offers require manual checking. A rate you type yourself stays constant for the whole projection.
Why might my bank pay a different amount?
Many banks calculate interest daily and credit it monthly. Actual deposit dates, differing month lengths, rounding, balance tiers, fees, withdrawals and bonus conditions all affect the result. This is a monthly planning approximation.