Lab
Mortgage Lab
Compare mortgage scenarios with different terms, rates, and tranches. Visualize payment timelines and uncertainty.
alpha
- finance
- nl
- mortgage
- calculator
- risk
Global settings
€
Post-Reset Rate Model
Display Options
€/mo
Highlights scenarios exceeding this amount
Scenarios
EditingAggressive (5yr)
€
Same payment each month
Divide mortgage into multiple fixed periods
€/mo
Key metrics
| +/− | |||||
|---|---|---|---|---|---|
| Aggressive (5yr) | € 1.730 | € 1.984 | +14.7% +€ 254 | € 2.242 if rate = 5.73% | € 298.938 (43% of total paid) |
| Conservative (20yr) | € 1.864 | € 1.926 | +3.3% +€ 62 | € 2.038 if rate = 5.73% | € 278.429 (41% of total paid) |
| Moderate (10yr) | € 1.796 | € 1.959 | +9.1% +€ 163 | € 2.172 if rate = 5.73% | € 285.788 (42% of total paid) |
Worst Case = payment at reset if the new rate lands at the top of the 90% uncertainty band.
- Lower initial payment
- Aggressive (5yr)
- € 1.730/mo
- Lowest total interest
- Conservative (20yr)
- € 278.429
- Most stable (lowest reset risk)
- Conservative (20yr)
- +€ 175/mo risk
Quick start guide
Understanding the chart
- Solid line: Your payment during the fixed rate period (you know exactly what this will be)
- Dashed line: Expected payment after rate reset (based on predicted market rate)
- Shaded area: Uncertainty range (90% confidence) - your actual payment will likely fall in this band
- Vertical line: When your fixed period ends and rate resets
Key decisions
- Lower initial payment? Choose shorter fixed period (5yr) - but higher reset risk
- More stability? Choose longer fixed period (20yr) - pay slightly more now, less uncertainty later
- Lowest total interest? Compare in the metrics table below
- Risk tolerance: Check the "Worst Case" column - can you handle that payment?
Advanced features
- Tranche Mode: Split into multiple tranches (e.g., 70% @10yr / 30% @20yr)
- Extra Payments: Model monthly extras or lump sums to pay off faster
- Budget Guardrails: Set max comfortable payment to highlight risky scenarios