Loan Repayment Calculator & Amortization Guide
Before you sign for a car loan, personal loan, or mortgage, it is crucial to understand the true cost of borrowing. Use our simulator to see exactly how much interest you will pay over time.
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True Cost Amortization Estimator
Enter your loan details to calculate your real monthly payment and total interest.
The True Cost of Borrowing
When you borrow money, you don't just pay back the principal (the amount you originally borrowed). The longer you take to pay it back, the more you pay in interest. This is why extending a loan from 3 years to 5 years lowers your monthly payment, but significantly increases the overall cost of the purchase.
Loan Example: A $10,000 Purchase
Visualizing your total interest is critical for financial planning. Here is how a standard $10,000 personal loan at 5% interest over 24 months breaks down:
Paying an extra $529 just for the privilege of borrowing money for two years is a cost that should be factored into your Monthly Budget before you ever visit the dealership or bank.
Amortization vs. Simple Interest
Banks calculate most standard loans (like car loans and mortgages) using an amortization schedule. This means your monthly payment stays the same, but the portion going toward interest versus principal changes every month.
The actual formula banks use to calculate your fixed monthly payment ($M$) looks like this:
Where P is the principal, r is your monthly interest rate (annual rate ÷ 12), and n is the total number of months.
Why Use Simple Sheet Instead of Excel?
While Microsoft Excel and Google Sheets are incredibly powerful, they are not designed for quick, on-the-go checks while you are at a dealership or bank. Conversely, basic note-taking apps lack mathematical functions. Simple Sheet bridges that gap perfectly.
| Feature | Excel / Sheets | Notes App | Simple Sheet |
|---|---|---|---|
| Live Math Calculations | ✅ | ❌ | ✅ |
| Mobile-Friendly Entry | △ (Clunky) | ✅ | ✅ |
| Easily Shareable URL | △ (Needs login) | ❌ | ✅ |
How to Estimate Repayments in Simple Sheet
While the calculator above uses the official bank formula, you can use our Simple Sheet Template for rapid, on-the-go estimations when you just need a quick baseline:
- Open the App: Click the "Open Full Template in App" button to load the loan template.
- Set Principal: Enter your total loan amount in the "Base" field at the top.
- Add Interest: Use the first row to add your total expected interest using the
%toggle and+operator. - Divide by Term: Use the second row to divide (
÷) that total amount by the number of months in your loan term. - Review Payment: The final result is your estimated baseline monthly payment!
Note: Because this template uses linear estimations, it will provide a baseline for your Savings Goal rather than a bank's official amortized quote.