Principal vs interest calculator
Show how a selected mortgage payment splits between principal and interest.
What this calculator covers
Use this principal vs interest calculator to inspect a specific payment inside a fixed-rate mortgage and see how much of that payment actually reduces the loan balance.
The walkthrough keeps the principal share, interest share, and remaining balance visible together so the changing amortization mix is easier to understand than in a full schedule table.
Frequently asked questions
- Why does so little of an early mortgage payment go toward principal?
- Each payment's interest charge is calculated on the outstanding balance at that moment, so when the balance is at its highest the interest piece is also at its largest. As you make payments and the balance falls, the interest portion shrinks and more of each fixed payment goes toward reducing principal.
- Does the principal-vs-interest split change on a fixed-rate loan?
- Yes. The monthly payment amount stays fixed for the life of the loan, but the allocation shifts continuously. Early payments are weighted heavily toward interest; later payments are weighted heavily toward principal. This is the defining feature of a fully amortizing schedule.
- What is the remaining balance shown here?
- It is the amount still owed on the loan immediately after the selected payment is applied. This is an estimate based on a standard amortization model, not an official lender payoff quote, which may differ due to rounding, escrow, or other account-specific factors.
- Does this include escrow, PMI, or extra payments?
- No. The calculation models only the principal-and-interest portion of a fixed-rate payment. Escrow (taxes and insurance), PMI, and any extra principal payments are outside this split and would need to be considered separately.
Tool
Run the calculation
Result
RESULT · PRINCIPAL
â„–055
Primary result
$397.88
At payment 60, a $320,000.00 fixed-rate loan has about $397.88 going to principal and $1,624.74 going to interest out of the $2,022.62 monthly payment.
- Principal payment
- $397.88
- Interest payment
- $1,624.74
- Principal share
- 19.67%
- Interest share
- 80.33%
- Remaining balance
- $299,554.97
Step-by-step solution
- 1.Use the mortgage amortization formula to set the monthly payment at $2,022.62.
- 2.Advance the schedule to payment 60 and split that payment into $397.88 of principal and $1,624.74 of interest.
- 3.Track the cumulative totals to estimate $20,445.03 of principal repaid, $100,912.17 of interest paid, and $299,554.97 still outstanding after that payment.
Walkthrough
Visual walkthrough
Every fixed mortgage payment includes both interest and principal, but the mix changes over time as the balance falls.
01
Start with the fixed payment
The loan amount, rate, and term determine one monthly payment for the full amortizing schedule.
$2,022.62 monthly payment
02
Split the selected payment
Interest is charged on the balance still outstanding at that moment, and the rest of the payment reduces principal.
$397.88 principal / $1,624.74 interest
03
Read how the mix is changing
The principal and interest shares show whether the payment is still mostly interest or whether more of it is now reducing the balance.
19.67% principal share