Debt calculator
Weighted Average Interest Rate Calculator
Estimate the blended interest rate across several balances by weighting each rate by the amount owed. This is useful when a single simple average would hide which loan or card balance drives the most interest cost.
Updated: June 10, 2026
Calculate weighted average rate
Formula
Weighted average interest rate equals the sum of each balance multiplied by its annual rate, divided by the sum of all balances. In shorthand: (balance × rate + balance × rate + balance × rate) ÷ total balance.
Worked example
If one balance is $1,000 at 10% and another is $3,000 at 20%, the simple average rate is 15%, but the weighted average is 17.50%. The larger 20% balance carries more weight, so the blended rate is closer to 20% than 10%.
How to interpret the result
The weighted rate is a summary of the listed balances, not a payoff plan. It can help explain the overall interest burden across cards, personal loans, auto loans, student loans, or other fixed balances. It does not show monthly payments, amortization, compounding details, fees, variable-rate changes, or creditor-specific payment allocation rules.
For payoff timing, use this page alongside the debt payoff calculator or debt avalanche calculator. To compare two new borrowing offers instead of existing balances, use the loan comparison calculator.
Common mistakes
- Using a simple average when balances are very different.
- Mixing promotional APRs, purchase APRs, and cash-advance APRs without noting which balance each rate applies to.
- Treating the estimated annual interest as an exact bill instead of a simple rate × balance snapshot.
- Forgetting that new charges, fees, minimum-payment formulas, and variable rates can change the real cost.
Related tools and guides
Estimate payoff time with the credit card payoff calculator, compare promotional-rate tradeoffs with the balance transfer calculator, review monthly debt pressure with the debt-to-income calculator, or read How to Compare Loans for broader borrowing-cost context.
For plain-English context, also read Debt-to-Income Ratio Explained if you want to connect blended borrowing cost with overall payment pressure.
Rate-bucket checklist
Result quality checklist
- Match each balance to the specific APR bucket that applies to it.
- Separate promotional, purchase, cash-advance, and penalty rates if statements split them out.
- Do not confuse weighted average cost with payoff speed or minimum-payment burden.
- Recheck the inputs after new purchases, fees, or rate resets.
- Use a payoff calculator separately if you need monthly timing or amortization.
Method and verification trail
- Method used: Each listed balance is multiplied by its entered annual rate, those weighted amounts are added together, and the total is divided by the total listed balance to estimate a blended annual rate.
- Primary source type to verify: Credit-card statements, loan statements, account dashboards, APR disclosures, and any promo-rate notices that split balances by rate bucket.
- What to verify in real documents: The current balance tied to each APR, whether rates are promotional or variable, whether cash advances or penalty APRs are separate, and whether any fee changed the balance recently.
- Scope limit: This page does not model compounding detail, statement timing, payoff order, minimum-payment rules, or lender-specific balance-allocation rules.
For site-wide methodology, review How We Calculate. For sourcing and corrections standards, review Editorial Policy.
FAQ
Is this weighted average the same as one account APR?
No. It is a blended summary across the balances and rates you enter. It does not replace any lender disclosure for an individual account.
Can a small high-rate balance matter less than a large low-rate balance?
Yes. Larger balances carry more weight in the blended rate, which is why weighted averages are more useful than simple averages for real debt snapshots.
Does this estimate monthly payments?
No. It estimates a blended annual rate and a simple annual interest snapshot only. Use payoff or loan calculators for payment timing.
Before you rely on a blended rate
Check whether each entered rate is fixed, variable, promotional, penalty, or tied to a specific purchase category. If real statements separate balances by APR bucket, enter the closest matching balance and rate pairs rather than averaging by account name alone.
For important decisions, compare this simplified estimate with account statements, loan agreements, disclosures, payoff letters, and any professional guidance that applies.