Guide / 01
When to use it
Use it to compare simple and monthly compounded returns, estimated tax, and maturity value for a lump-sum deposit such as 10,000,000 at 3.5% for 12 months.
CALC / 013
Deposit Interest Calculator
Estimate simple or monthly compound interest on a lump-sum deposit, including tax.
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355,670Gross interest
54,773Estimated tax
10,300,896Estimated maturity
Actual bank calculations and promotional rates may differ.
Guide / 02
Quick guide
- Enter the principal, annual rate, term in months, and tax rate applied to interest.
- Select simple interest or monthly compounding to match the product terms.
- Check that gross interest minus estimated tax plus principal equals the displayed maturity value.
Check
Validate the result
Set the tax rate to zero; estimated tax should become zero and maturity should equal principal plus gross interest.
Limits
Know the limits
The estimate treats the principal as a single deposit, not recurring monthly contributions. Bank day-count rules, payment timing, promotional rates, exemptions, and early withdrawal are not included.
Reference
Input and output example
Use the same units and settings when comparing your result with this example.
- Example input
Principal 10,000,000 · annual rate 3.5% · 12 months · tax 15.4% · simple interest- Result and interpretation
Gross interest 350,000 · tax 53,900 · maturity 10,296,100 This assumes one initial deposit, not monthly contributions.
FAQ
Frequently asked
Can I enter my monthly savings contribution as the principal?
Not for an accurate recurring-deposit result. Each contribution earns interest for a different length of time, whereas this calculator assumes the entire principal is deposited at the start.
Does my data leave this device?
No. This tool is designed to process its working data in your browser. Advertising may load separately, but your tool input is never sent with it.