Interest Rate Calculator
Free Online Interest Rate Calculator
Find the Rate · APR / APY Converter · Loan Rate Analyzer
Interest Rate Calculator
Find the Rate · APR / APY Converter · Loan Rate Analyzer
Enter any three of the four variables — principal, final value, time, or rate — and solve for the missing one. Works for both compound and simple interest. Useful for reverse-engineering returns on savings accounts, investments, or historical data.
What Are You Solving For?
Known Values
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$
yrs
%
Interest Rate
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Rate Analysis
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Solved Value
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Verification Check
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Principal (P)
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Final Value (A)
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Time Period (t)
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Interest Rate (r)
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Total Interest
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EAR (Effective Annual)
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Growth Multiplier
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Rule of 72
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🔮 Rate Scenarios
At this rate — value after 10 years:—
Rate needed to double in same time:—
Rate needed to triple in same time:—
How long to double at this rate (Rule of 72):—
Real rate after 3% inflation:—
Rate Insights
APR (Annual Percentage Rate) is the nominal rate. APY (Annual Percentage Yield) is the effective rate after compounding. Banks advertise APR on loans (looks lower) and APY on savings (looks higher). Convert between them and compare any rate across all compounding frequencies.
Enter Either APR or APY
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%
$
yrs
APR / APY Conversion
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APY (Effective Rate)
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APR (Nominal Rate)
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APY at Every Compounding Frequency (same APR)
APR (Nominal)
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APY (Effective)
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Rate Spread (APY−APR)
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Compounding Periods/yr
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Final Value at APY
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Final Value at APR (simple)
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Extra Earnings (APY vs simple)
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Monthly Interest Amount
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🔮 APR / APY Scenarios
APR needed to match this APY with annual compounding:—
If compounded daily instead (same APR):—
Credit card at this APR — monthly rate:—
0.25% higher APY over 10 years on $10K:—
Real APY after 3% inflation:—
APR / APY Insights
Reverse-engineer the true interest rate on any loan from its monthly payment. Compare loan offers, calculate what rate makes two loans equivalent, and see the true annual cost including fees — the actual APR that lenders are required to disclose.
Loan Details
$
$
months
$
$
Implied Annual Interest Rate (APR)
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Loan Rate Assessment
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Total Interest Paid
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True APR (with fees)
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Loan Amount
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Monthly Payment
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Term
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Implied APR
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Total Paid
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Total Interest
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Interest as % of Principal
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True APR (with fees)
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💸 Total Cost Breakdown
📋 Annual Amortization Summary
| Year | Principal Paid | Interest Paid | Total Paid | Balance | Int. % |
|---|
🔮 Loan Rate Scenarios
If rate was 2% lower:—
If rate was 2% higher:—
Extra $100/month toward principal:—
Opportunity cost: invest payment instead at 8%:—
Break-even vs investing (rate vs 8% return):—
Loan Rate Insights
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