📖 Overview
Use this calculator to test affordability before signing a personal loan agreement.
🧪 Example Scenarios
Use these default and higher-pressure example inputs to explore how sensitive this calculator is before using your real numbers.
| Input | Base Case | Higher Pressure Case |
|---|---|---|
| Loan Amount ($) | 30,000 | 34,500 |
| Annual Interest Rate (%) | 7.5 | 9 |
⚙️ How It Works
This uses a fixed-payment amortization formula over a 60-month schedule to estimate monthly repayment.
The Formula
M = P × [r(1+r)ⁿ] / [(1+r)ⁿ − 1]
| M | Monthly payment |
| P | Loan principal |
| r | Monthly rate = Annual APR ÷ 12 ÷ 100 |
| n | 60 for a 5-year (60-month) loan |
💡Even a 2% APR difference on a $20,000 5-year loan adds roughly $1,100 in total interest. Shopping multiple lenders is worthwhile.
Quick Reference
| Loan | 5% APR / mo | 7% APR / mo | 10% APR / mo |
|---|---|---|---|
| $10,000 | $188.71 | $198.01 | $212.47 |
| $20,000 | $377.42 | $396.02 | $424.94 |
| $30,000 | $566.14 | $594.04 | $637.41 |
| $50,000 | $943.56 | $990.06 | $1,062.35 |
When To Use This
- Use this tool when you need a fast decision during active planning or execution.
- Use this before committing money, time, or tradeoffs that are hard to reverse.
- Use this to compare options using the same assumptions across scenarios.
Edge Cases To Watch
- Results can be misleading if key inputs are missing, stale, or unrealistic.
- Very small or very large values may amplify rounding effects and interpretation risk.
- If assumptions change mid-decision, recalculate before acting.
Practical Tips
💡 Compare lenders using both APR and monthly payment.
💡 Shorter terms usually lower total interest but raise monthly cost.
💡 Test affordability against your lowest expected monthly income.
Frequently Asked Questions
❓ Is this only for car loans?
No. The same math applies to many fixed installment loans.
❓ What if rate is zero?
The payment becomes a simple principal divided by months.