Interest Calculator
Compare simple and compound interest estimates across rate, term, and compounding assumptions
Calculate with Interest Calculator
Investment Details
Interest & Term
Results
Simple Interest vs Compound Interest
* Comparison based on initial principal only, without additional contributions
Accumulation Schedule
| Year | Deposit | Interest | Balance |
|---|---|---|---|
| 1 | $5,000 | $1,114 | $26,114 |
| 2 | $5,000 | $1,419 | $32,533 |
| 3 | $5,000 | $1,740 | $39,273 |
| 4 | $5,000 | $2,077 | $46,350 |
| 5 | $5,000 | $2,431 | $53,781 |
Assumptions
Use Interest Calculator for financial estimate planning when you need a clear estimate, transparent inputs, and a result you can review before taking the next step.
Worked example
When To Use Interest Calculator
- Start with a representative scenario in Interest Calculator so rates, dates, balances, or other key assumptions match the question you are comparing.
- Review whether the estimate matches the planning scenario before you use it for a budget, plan, or discussion.
Sample Input And Output Checks
- Start with inputs that match the real scenario, not only a rounded placeholder.
- Review amount, rate, term, timing, fees, tax treatment, and decision horizon before trusting the output.
- Use the result as an estimate to review against statements, lender terms, tax forms, quotes, or qualified advice when the decision is material.
About This Tool
Compare Simple and Compound Interest on One Scenario
This interest calculator compares simple interest and compound interest using the same principal, annual rate, and term so the difference is easy to read. Simple interest applies the rate only to the original principal: Interest = Principal x Rate x Time. Compound interest adds interest back into the balance at the selected frequency, so later periods use a larger base. The result is an estimate based on the assumptions you enter, not a recommendation to choose a product or investment. For detailed calculations with regular contributions and scenario ranges, explore our Compound Interest Calculator.
How Compounding Frequency Changes the Estimate
Compounding frequency controls how often interest is added back to the balance. The calculator can compare annual, semi-annual, quarterly, monthly, and daily compounding with the same principal and rate. More frequent compounding usually increases the ending balance in the model, but the difference may be small for short terms or low rates. When comparing real accounts, check the stated APY, fees, withdrawal limits, taxes, and product terms rather than relying only on the calculated balance. Use our Interest Rate Calculator when you need an APR/APY conversion for a separate rate comparison.
When Regular Contributions Need a Separate Model
This page is best for one principal amount and a fixed rate assumption. If you want to add monthly or annual deposits, use a contribution-based calculator so the result separates starting principal, added money, and interest. Contribution projections are sensitive to timing, rate assumptions, taxes, and fees, so treat them as comparison ranges rather than guarantees. For broader projections with recurring contributions, scenario assumptions, and inflation context, explore our Investment Calculator.
Practical Uses and Assumptions to Check
Use this calculator for quick comparison tasks: checking a quoted savings rate, comparing two compounding schedules, or seeing how term length changes a fixed-rate estimate. Before using the result in a real decision, verify whether the rate is APR or APY, whether interest is taxable, whether fees apply, and whether the product has penalties or balance limits. Loan products use separate payment and amortization rules, so use our Loan Calculator or Mortgage Calculator when the question is about payments, payoff timing, or principal reduction.