APR vs APY Calculator - Compound Interest Comparison

Calculation Type

Input Details

Stated annual interest rate

How often interest compounds

Understand the true cost or return of your money!

APY reveals the real rate after accounting for compound interest.

APR vs APY: Understanding the Difference

APR (Annual Percentage Rate) and APY (Annual Percentage Yield) are both measures of interest rates, but they serve fundamentally different purposes. According to the FDIC, understanding this distinction is crucial for making informed financial decisions about savings and borrowing.

๐Ÿ”‘ Key Distinction

  • APR = Simple annual rate (no compound interest)
  • APY = Effective annual rate (includes compound interest)
  • APY is ALWAYS the true rate you earn or pay!

What is APR (Annual Percentage Rate)?

APR is the nominal or stated annual interest rate without accounting for the effect of compound interest within the year. It represents simple interest as if it were calculated and paid once annually.

Where APR is used:

  • Credit cards: Stated APR on purchases (e.g., 18% APR)
  • Mortgages: Loan interest rate including some fees
  • Auto loans: Annual financing rate
  • Personal loans: Borrowing cost before compounding
  • Student loans: Interest rate disclosed to borrowers

APR formula (simple interest):

Interest = Principal ร— APR ร— Time

Example: $10,000 at 5% APR for 1 year = $10,000 ร— 0.05 ร— 1 = $500 interest

What is APY (Annual Percentage Yield)?

APY is the effective annual rate that accounts for compound interest. It shows what you actually earn or pay when interest compounds multiple times per year and you earn "interest on interest."

Where APY is used:

  • Savings accounts: Must disclose APY by law (Truth in Savings Act)
  • Money market accounts: True earnings with compounding
  • Certificates of Deposit (CDs): Actual yield over term
  • Investment returns: Real return with reinvestment
  • High-yield savings: Competitive rates with compounding

APY formula (compound interest):

APY = (1 + r/n)^n - 1

Where:
r = APR as decimal (5% = 0.05)
n = number of compounding periods per year

Example: 5% APR with monthly compounding
APY = (1 + 0.05/12)^12 - 1 = 1.05116 - 1 = 0.05116 = 5.116%

The Power of Compound Interest

Compounding frequency determines how much APY exceeds APR. The more frequently interest compounds, the higher your APY relative to APR.

Compounding FrequencyTimes Per Year5% APR โ†’ APY$10,000 Earns
Daily3655.127%$512.67
Monthly125.116%$511.62
Quarterly45.095%$509.45
Semi-annually25.063%$506.25
Annually15.000%$500.00

Key insight: Daily compounding earns $12.67 more per year than annual compounding on just $10,000. On $100,000, that's $126.70 extra annually - enough for a nice dinner each year just from compounding!

Real-World Applications

For Savers: Maximizing Returns

When comparing savings accounts, always use APY, not APR:

Savings Account Comparison

  • Account A: 4.40% APR, daily compounding = 4.50% APY
  • Account B: 4.45% APR, monthly compounding = 4.55% APY
  • Account C: 4.50% APR, quarterly compounding = 4.58% APY
  • Best choice: Account C (highest APY = most earnings)
  • On $25,000: Account C earns $1,145/year vs Account A's $1,125 = $20 extra

For Borrowers: Understanding True Cost

Credit cards state APR but charge interest with daily compounding, making the effective cost higher:

Credit Card True Cost

  • Stated rate: 18% APR (advertised)
  • Compounding: Daily (365 times per year)
  • True cost: 19.72% APY (what you actually pay)
  • On $5,000 balance:
  • APR suggests: $900/year interest
  • APY reality: $986/year interest
  • You pay $86 more than APR suggests!

When APY Matters Most

High-impact scenarios:

  • Large balances: Even 0.1% APY difference on $100,000 = $100/year
  • High interest rates: 10% APR compounds to 10.52% APY (daily) - 0.52% difference is significant
  • Long time periods: Compounding effect multiplies over years and decades
  • Credit card debt: Daily compounding makes stated APR very misleading
  • Investment comparisons: True return requires APY, not APR

Low-impact scenarios:

  • Low rates (under 1%): APR vs APY difference is minimal (pennies)
  • Small balances (under $1,000): Practical difference measured in cents
  • Short terms (under 1 year): Compounding hasn't had time to work
  • Annual compounding: APY = APR, no difference

Why Banks Show Different Rates

Regulatory requirements from the Truth in Savings Act (Regulation DD) dictate disclosure rules:

  • Savings accounts MUST show APY: Protects consumers by showing true earnings
  • Loans typically show APR: Industry standard for borrowing costs
  • Credit cards show APR: Not required to disclose APY (which would be higher)
  • Marketing tactic: Banks highlight whichever number looks better (APY for savings, APR for loans)

How to Use This Calculator

Our APR vs APY calculator helps you:

  • Convert APR to APY: See true rate with any compounding frequency
  • Compare multiple accounts: Standardize rates to APY for accurate comparison
  • Calculate real earnings: See exact dollar impact on any balance
  • Evaluate compounding effect: Test how daily vs monthly vs quarterly affects returns
  • Understand loan costs: Calculate true cost of credit card debt with daily compounding
  • Make informed decisions: Choose best savings account or lowest-cost loan based on facts

For related calculations, explore our Compound Interest Calculator for growth projections, Savings Calculator for goal planning, Loan Calculator for borrowing costs, and Investment Calculator for portfolio returns.

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