Works for mortgages, auto loans and any fixed-rate installment loan. Extra payment applies fully to principal.
📊 Amortization Schedule
| Month | Payment | Principal | Interest | Balance |
|---|
🏦 What Is a Loan Calculator?
A loan calculator computes the relationship between four core numbers behind any fixed-rate installment loan — the loan amount, the interest rate, the term (how long you have to repay it), and the monthly payment. Give it any three, and it solves for the fourth. This calculator also builds a full amortization schedule, showing exactly how much of each monthly payment goes toward interest versus principal, and how quickly an extra payment each month can shorten a loan and cut the total interest paid.
📖 How to Use This Calculator (With Example)
Say you're taking out a $300,000 mortgage at 6% annual interest for 30 years. Set Solve For to "Monthly Payment", enter Loan Amount = 300000, Rate = 6, Term = 30 years, and click Calculate. The result shows a monthly payment of approximately $1,798.65, with total interest over the life of the loan of about $347,515. Now try adding $200 to Extra Monthly Payment — the payoff time drops from 360 months to roughly 279 months, saving over $91,000 in interest.
🔢 Formula Used
Where M is the monthly payment, P is the loan amount, r is the monthly interest rate (annual rate ÷ 12), and n is the total number of monthly payments. Solving for loan amount or term rearranges this same equation; solving for the interest rate requires an iterative numerical method since there's no direct algebraic solution.
👥 Who This Is For
- Homebuyers comparing mortgage offers or checking what payment fits their budget
- Car buyers figuring out a realistic auto loan payment before visiting a dealership
- Anyone with an existing loan wanting to see how much an extra payment actually saves
- Borrowers comparing offers — solve for the real interest rate behind a quoted payment
📊 ThinkForU vs Other Loan Calculators
| Feature | ThinkForU ⭐ | Typical Bank Sites |
|---|---|---|
| No Login Required | ✅ | ✅ |
| Zero Data Storage | ✅ | ❌ |
| Full Amortization Table | ✅ | Often paywalled |
| Solve for Rate or Term | ✅ | Rarely offered |
| Extra-Payment Savings | ✅ | ❌ |
| Downloadable Result | ✅ | ❌ |
How is a loan payment calculated?
Using the standard amortization formula, based on the loan amount, the interest rate per period, and the total number of payments.
What is amortization?
The process of paying off a loan through regular payments, where each payment covers that period's interest first and the remainder reduces the principal balance.
Does paying extra each month really save that much interest?
Yes — extra payments apply entirely to principal, reducing the balance interest is calculated on for every remaining month, often saving tens of thousands of dollars on a mortgage-sized loan.
Why do early payments go mostly toward interest?
Early on, the balance is at its highest, so the interest portion of each payment is largest. As the balance shrinks, more of each fixed payment goes toward principal.
Can I use this for any type of loan?
Yes — the same amortization math applies to mortgages, auto loans, personal loans, and any other fixed-rate installment loan.
What's the difference between loan term and amortization period?
For most personal and auto loans they're the same. Some mortgages have a shorter term with payments based on a longer amortization period, requiring refinancing or a lump sum at the end.
Why is my real payment different from what this calculator shows?
This calculator computes principal and interest only — your actual bill may also include property tax, insurance, or lender fees.