INPUT LEDGER
What is known, entered, or assumed.
| Input | Value | Origin |
|---|---|---|
| Loan principal | ₩480,000,000 | Held constant |
| Term | 30 years / 360 payments | Held constant |
| Lower-rate case | 3.5% | Illustrative assumption |
| Higher-rate case | 5.0% | Illustrative assumption |
REPRODUCIBLE CALCULATION
Follow the intermediate result.
3.5% payment
Formula or rule: Standard equal-payment formula
Result: About ₩2,155,415 per month
5.0% payment
Formula or rule: Same principal and term
Result: About ₩2,576,744 per month
Monthly difference
Formula or rule: ₩2,576,744 − ₩2,155,415
Result: About ₩421,329
First-year cash difference
Formula or rule: ₩421,329 × 12
Result: About ₩5,055,948
DECISION READING
What the result means.
A property can fit at one assumed rate and fail the same household budget at another. APT should therefore expose the rate as an editable assumption rather than burying it inside a score.
SENSITIVITY
What could change the answer.
- Shorter terms usually raise the monthly payment while reducing total interest.
- A larger cash contribution reduces both payments, but ties up more capital.
- Actual products can use different repayment structures, fees, and rate-reset rules.
BOUNDARIES
What this case does not prove.
- The calculation assumes a constant nominal rate for the full term.
- It excludes fees, insurance, early repayment, and lender-specific schedules.
- The two rates are scenarios, not current offers.
OFFICIAL SOURCES
Where factual context is verified.
RELATED APT CASES
Change one assumption and compare again.
Each case keeps inputs, arithmetic, evidence, and uncertainty in separate layers.