HELOC Payment, Repayment Shock & CLTV Method, Formula & Examples
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This method guide explains the calculation sequence behind the HELOC Payment, Repayment Shock & CLTV Calculator. It owns formulas, input definitions, timing, rounding and reference checks; the calculator remains the only page that performs the numeric scenario.
Calculation sequence
Interest-only payment equals the entered balance times the monthly rate. Repayment uses standard amortization over the entered repayment period. CLTV combines the first mortgage with the draw or full line and divides by home value.
Inputs and evidence
Use current written documents for every material input. The calculator supports: Market and currency, Current home value, First-mortgage balance, HELOC credit limit, Modeled HELOC balance, Current HELOC annual rate, Stress annual rate, Interest-only draw period, Repayment period, Upfront and closing fees.
Reference example
With a 50,000 draw, zero interest and a ten-year repayment period, principal-only repayment is 416.67 per month. Against a 500,000 home and 300,000 first mortgage, draw CLTV is 70%.
Boundary and error checks
Test zero-rate branches where available, minimum and maximum supported inputs, and a scenario in which the main result reverses. Reject blank, non-finite or out-of-range values rather than silently substituting them.
Model boundary
Rates may change, minimum-payment formulas differ and the line can be frozen or reduced. The model does not determine approval, available equity, property value, tax deductibility or foreclosure risk.
Sources and review status
Sources and model boundaries checked 2026-10-08. CalculatorGeek Editorial Team verified this page for publication on 2026-10-16. Existing formulas, source dates, model boundaries, and professional-advice limitations remain in force.
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