If you take out a HELOC with a $50,000 limit and draw the full amount, your monthly payment will depend on whether you make interest-only payments or interest and principal payments to start.Say the HELOC has a 9 percent interest rate and you plan to pay it off in 20 years. You’d need to pay $453 per month to reach that goal.If you want to explore a scenario of your own, use our HELOC payoff calculator.