Browse all calculators →
Loans & Debt
Total Interest Paid Calculator Personal Loan Calculator Loan Repayment Calculator Loan Comparison Calculator
More
All Calculators Guides
Home› Calculators› Loans & Debt› Total Interest Paid Calculator

Total Interest Paid Calculator
with Full Borrowing Cost Breakdown

Calculate how much total interest you will pay over the life of a fixed-rate loan, compare extra-payment scenarios, and see how interest changes the full cost of borrowing.

Currency
📊
Total Interest Paid Calculator
Section 1: Loan Details
€
Original amount borrowed.
%
Fixed annual interest rate used for the full repayment term.
⏱
Choose whether the term is entered in years or months.
yrs
Total planned repayment period.
📅
Optional, used only for the payoff date estimate.
Section 2: Payment Options
€
Optional extra amount paid each month above the scheduled payment.
€
Optional fee added to total borrowing cost, but not added to principal.
Total Interest Paid
—
full interest over the actual payoff schedule
Total Repaid
—
principal plus interest
Total Cost Including Fee
—
total repaid plus upfront fee
Monthly Payment
—
scheduled payment plus any extra monthly amount
Interest Saved
—
compared with the base schedule
Months Saved
—
compared with the base schedule
Payoff Date
—
based on start date if provided
Interest as % of Principal
—
total interest divided by original loan amount
Full Breakdown
Loan amount—
Annual interest rate—
Term—
Scheduled monthly payment—
Extra monthly payment—
Upfront fee—
Total interest paid—
Total repaid—
Total cost including fee—
Interest saved—
Months saved—
Payoff date—
Interest as % of principal—
Interest Cost Scenarios
Scenario Monthly Payment Total Interest Paid Total Repaid Months to Pay Off Interest Saved vs Base
Amortization Schedule
Month Payment Principal Interest Balance
Principal vs Interest vs Fee
Principal
Interest
Fee
✦ Cal, AI Explanation
Cal is reviewing your total interest result...
💬 Ask Cal about total interest paid
Cal
Your result is ready. Ask me how much of the loan cost is interest, how extra payments change the total, or whether the term is making the loan more expensive.

💡 Interest Cost Tips

Longer repayment terms usually increase total interest even when the monthly payment looks easier.
Extra monthly payments reduce interest fastest in the early part of the repayment schedule.
A lower monthly payment can hide a significantly higher total borrowing cost.
Fees increase the total cost of borrowing even when they are not added to the loan balance.
Zero-interest loans behave differently because total interest stays at zero.

Related Calculators

Personal Loan Calculator→ Loan Repayment Calculator→ Loan Comparison Calculator→ Loan Affordability Calculator→ Car Loan Calculator→

Related Guides

How Loan Interest Works→ How to Reduce Total Interest Paid→ Why Loan Term Matters→

How total interest is calculated

Total interest paid is the sum of all interest charges applied over the full life of a fixed-rate loan. Each month, interest is charged on the remaining balance, not on the original loan amount. That means the interest share is highest early in the schedule and falls over time as the balance is reduced.

Because the balance is highest at the beginning, the early monthly payments contain a larger interest component. Over time, more of each payment goes to principal. This repayment pattern is called amortization, and it is the reason extra payments made early can materially reduce total interest.

The core formulas

M = P × [r × (1 + r)^n] / [(1 + r)^n - 1]
Total Interest = Total Repaid − Principal
Total Cost Including Fee = Total Repaid + Upfront Fee
M = monthly payment, P = principal, r = monthly interest rate, n = number of monthly payments.

Why term length changes borrowing cost

A longer term usually lowers the monthly payment, but it also keeps the balance outstanding for more months. More months means more interest charges in total, which is why a cheaper-looking monthly payment can produce a more expensive loan overall.

A shorter term usually increases the monthly payment but reduces the total interest paid. The trade-off is between monthly affordability and long-run borrowing cost.

Example comparison table

Loan Rate Term Monthly Payment Total Interest
€10,000.005.00%3 years€299.71€789.52
€25,000.006.50%5 years€489.11€4,346.53
€50,000.007.50%7 years€754.92€13,413.31
€100,000.004.90%10 years€1,054.19€26,502.57

Frequently Asked Questions

How much interest will I pay in total?+
This depends on the loan amount, interest rate, repayment term, and whether you make any extra payments. This calculator works it out by simulating the full amortization schedule month by month until the balance reaches zero.
Why do longer loans cost more?+
Longer loans usually keep the balance outstanding for more months. More months means more interest charges, so even if the monthly payment is lower, the total repayment can still be materially higher.
Do extra payments reduce total interest?+
Yes. For fixed-rate amortizing loans, extra payments reduce the balance faster, which lowers the base used to calculate future interest. That often shortens the payoff period and reduces total interest materially.
Does a fee count as interest?+
No. A fee is not interest. This calculator keeps the upfront fee separate from the loan balance and adds it only to the total cost summary so you can see the full borrowing cost more clearly.
What happens if the loan has 0% interest?+
If the interest rate is zero, total interest stays at zero and total repaid equals the original principal. Extra monthly payments still shorten the payoff period, but they do not create any interest savings because no interest is charged.