Affordability Metrics
Primary metric
Months of net salary to buy a 60m2 flat – computed as:
months = flat_60m2_price / avg_monthly_wage_net
On the homepage and compare page, this is displayed as years (months / 12).
Net wage calculation
Gross wages from CZSO are converted to net using Czech 2025 tax rules:
- 12.2% social/health insurance
- 15% / 23% income tax (progressive brackets)
- 2,570 CZK/month personal tax credit
Implemented in compute/czech_tax.rs.
Additional metrics
| Metric | Formula |
|---|---|
| Flat price | avg_price_m2 * 60 |
| Mortgage payment | Standard amortization formula (default: 80% LTV, 30y) |
| Payment-to-wage ratio | monthly_payment / net_wage * 100 |
| Rent vs mortgage | monthly_rent / monthly_payment |
| Monthly savings | net_wage - living_expenses |
| Years to save | Future value of annuity formula (default: 7% annual return) |
Severity colors
Based on months-to-buy:
- heat-1 (green): < 100 months
- heat-2: 100-110
- heat-3: 110-130
- heat-4: 130-160
- heat-5 (red): > 160 months