Cost of Waiting (Rate-Rise Scenario)
Side-by-side P&I and lifetime interest at today's rate vs a user-supplied future rate.
Example
You enter
- Principal (loan amount, $) 320000
- Current rate (percent) 6.5
- Future rate (percent) 7.5
- Term (years) 30
You get
- Monthly P&I at current rate $2022.62
- Monthly P&I at future rate $2237.48
- Monthly delta 214.86
Checked against published worked examples from: Standard mortgage amortization at two rates (public).
Details, formula, and sources
ScopeSame loan, same term; no forecasting. A what-if, not a recommendation.
Formula or tableP&I at current rate vs P&I at future rate, same principal and term. monthly_delta = pi_future - pi_now; total_interest_delta = (pi_future - pi_now) * n.
Source and editionStandard mortgage amortization at two rates. No forecasting model; both rates are user-supplied.
Free accessUnderlying formula is public. No specific source authority; this tile is a comparison aid.
What governsEstimate. Lender governs final underwriting and rate / fee disclosure. Appraiser governs the appraised value. State law and the agency's program guidelines may impose stricter limits than the published thresholds.
API field namesprincipal, current_rate_percent, future_rate_percent, term_years, monthly_pi_now, monthly_pi_future, monthly_delta
- Constant principal same loan amount and same term at both rates; in practice future buying power may differ if prices have movedconvention; the tile names this gap in the citation
- No prepayment 30-year fixed held to maturity; in practice refinances and sales often shorten the lifetimeconvention