Blended Rate Calculator NZ
This blended rate calculator works out the single interest rate that represents a whole mix of debts, so you can see what your borrowing really costs across a mortgage, a car loan and a credit card at once. Enter the balance and interest rate for each loan, and the calculator weights every rate by its share of the total balance, then combines them into one blended rate. A big balance at a low rate pulls the blended figure down, while a small balance at a high rate nudges it up, which is why the result usually sits close to your largest debt. Alongside the blended rate you get your total balance and the total interest those debts cost you over a year, so you can compare your current position against a single consolidation loan or a balance transfer offer. Lenders and accountants use the same weighted average approach to describe a portfolio of facilities on one line. Use it before you consolidate, when you refinance, or any time you want a clear headline number instead of juggling several rates in your head. Enter rates as annual percentages and balances in dollars, and leave any unused rows blank.
Enter the current balance and the annual interest rate for each debt. Leave rows you do not need blank. The blended rate is weighted by balance, so your biggest debt has the most influence.
Your $270,000 of balances behaves like a single loan at 7.10%, costing about $19,183 in interest a year.
Rates are annual percentages and this is a snapshot: as balances change, so does the blend. It ignores fees, compounding differences and repayment order. Estimate only.
How it works
The blended rate is a weighted average of your interest rates, where the weight is each debt's share of the total balance. Every balance is multiplied by its rate, those products are added together, and the total is divided by the sum of all the balances. Because the weighting is by dollars, a large balance at a low rate counts far more than a small balance at a high rate, so the blended rate lands near your biggest debt and drifts up only a little for smaller, dearer debts. The yearly interest figure is simply the blended rate applied to the total balance, which is the same as adding up the interest on each debt on its own.
Worked example
Say you owe 250,000 on a mortgage at 6.5%, 15,000 on a car loan at 12.9%, and 5,000 on a credit card at 19.95%. Multiply and add: 250,000x6.5 + 15,000x12.9 + 5,000x19.95 gives 1,918,250. Divide by the total balance of 270,000 and the blended rate is about 7.10%. Applied to the full 270,000, that rate costs about $19,183 in interest over a year, which matches the interest on the three debts added together. Notice how the 6.5% mortgage keeps the blend low even though the credit card sits near 20%.
Related calculators
- Debt Consolidation Calculator: fold debts into one loan.
- Weighted Average Calculator: any weighted mean.
- Mortgage Effective Interest Rate Calculator: true rate with fees.
- Loan Calculator: repayments on a single loan.