HELOC Draw and Repayment Phase Calculator
How to Build a HELOC Scenario
Enter one deliberately simplified draw path so the phase change remains visible.
Select a display currency.
Constant rate is a strong simplification
Many HELOCs use variable rates. Run additional scenarios rather than treating one entered rate as a forecast.
A Fixed-Draw Two-Phase Model
The model assumes the full entered draw is outstanding from the first draw month, no additional draws or principal payments occur, and monthly payments equal interest only. At the repayment transition, the same principal is amortized into equal monthly payments over the entered repayment term. The same nominal rate is held constant throughout. The CLTV comparison is arithmetic at your entered percentage, not an available credit limit.
HELOC Phase Examples
Constant 9% two-phase scenario
Fixed-draw assumptions
Phase payment estimate
The model charges $45,000 draw-phase interest and then amortizes $50,000 over 180 months.
Zero-rate boundary
Fixed-draw assumptions
Phase payment estimate
No interest accrues, so repayment divides principal evenly.
Test payment shock
Compare the repayment payment with the interest-only amount and rerun the model at higher rates.
Frequently Asked Questions
Still have questions about this calculation?
Try the CalculatorHELOC Phase Formulas
Interest-only and amortizing phases use the same constant nominal annual rate.
Formula
Interest-only payment
draw × annual rate / 12
Draw-phase interest
interest-only payment × draw months
Repayment payment
PMT = draw × r / (1 − (1+r)^−n)
Available line at entered CLTV
max(0, home value × entered CLTV − existing mortgage balance)
Scientific Background
CFPB explains that a HELOC is revolving credit secured by a home, commonly with a draw period followed by repayment, and warns that payments may rise. Federal Reserve consumer guidance describes variable-rate plans and index-plus-margin pricing. This calculator does not predict those changes.