How to Use Blended Rate Calculator
The Blended Rate Calculator is straightforward to use:
- Add a loan or deposit — Enter its principal and annual rate.
- Add more rows — Click + Add loan until all your balances are represented.
- Read the result — The Blended Rate Calculator shows the weighted-average rate, total principal, and weighted annual interest.
Formula & Theory - Blended Rate Calculator
The Blended Rate Calculator uses the principal-weighted average:
BlendedRate = Σ (Principal_i × Rate_i) / Σ Principal_i
TotalPrincipal = Σ Principal_i
WeightedInterest = Σ (Principal_i × Rate_i)This formula assumes:
- All rates are expressed as the same nominal annual rate (APR).
- All accounts compound at the same frequency, or have been pre-converted to effective annual rates.
- All accounts share the same time horizon (so weighting only depends on principal).
Why principal weighting? The interest paid (or earned) by an account in a given period equals Principal × Rate × Time. When you sum the interest across accounts and divide by total principal × time, the time cancels out and you’re left with a principal-weighted rate average.
Example:
- Loan A: $10,000 at 8%
- Loan B: $30,000 at 5%
- BlendedRate = (10,000 × 0.08 + 30,000 × 0.05) / 40,000 = (800 + 1,500) / 40,000 = 5.75%
A common use of the Blended Rate Calculator is to evaluate a debt consolidation offer: if a single refinance loan has a rate below the blended rate of your existing debts, it saves money before accounting for fees and term changes.
Use Cases for Blended Rate Calculator
- Debt consolidation analysis — Compare a consolidation loan’s rate to the blended rate of your current debts.
- Student loan refinancing — Federal + private mix often has a blended rate; refinancing makes sense only if the new rate is lower.
- Mortgage + HELOC combo — Compute the effective rate when first and second mortgages coexist.
- Deposit portfolio yield — Bank deposits + CDs + money market accounts — what’s your overall savings rate?
- Business financing — Mix of term loans, lines of credit, and SBA loans — what’s the company’s blended cost of debt?
- Comparison shopping — Quickly evaluate whether a new offer beats your existing weighted rate.
The Blended Rate Calculator gives you a single number that captures the financial reality of a portfolio of rates.