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Free HELOC interest-only calculator to calculate draw period payments, repayment phase costs, and payment shock. Calculate total interest for home equity lines of credit. Our calculator uses standard amortization formulas to project your interest-only payments during the draw period and principal plus interest payments during the repayment period, showing exactly how much your payment will increase.
Last updated: February 2, 2026
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Used to calculate loan-to-value ratio
$625.00/mo
Total interest: $75,000
$805.59/mo
Total repayment: $193,342
+28.9%
Payment increases by $180.59/month
Total Interest Paid
$168,342
Loan-to-Value
25.0%
$300,000
Typical period
10 Years
Interest-only payments on outstanding balance
Typical period
10-20 Years
Fully amortizing principal and interest payments
Typical increase
100-300%
Significant payment increase when principal repayment begins
Interest components
Draw + Repayment
Total interest paid over entire loan term
Typical max
80-85% CLTV
Combined loan-to-value including first mortgage
Shows details
Principal & Interest
Yearly breakdown of payments and remaining balance
$100,000 HELOC at 7.5% with 10-year draw and 20-year repayment:
Draw Payment
$625
Repayment
$806
Increase
+29%
Total Interest
$168K
Our HELOC interest-only calculator analyzes both phases of your home equity line of credit: the draw period (interest-only) and the repayment period (principal + interest). The calculator uses standard loan amortization formulas to project your payments in each phase, calculate the payment increase when the draw period ends, and show total interest costs over the life of the loan.
The dramatic payment increase from draw to repayment period (often 100-300%) is called "payment shock." In this example, the payment increases from $625 to $805 (29% increase) because we're amortizing over 20 years. A shorter repayment period would result in a much higher payment and greater payment shock.
Visualization of payment structure across draw and repayment periods
HELOCs have a unique two-phase structure. During the draw period (typically 10 years), you can borrow up to your credit limit, repay, and reborrow as needed, while only paying interest on the outstanding balance. This flexibility makes HELOCs popular for renovations, emergencies, and ongoing expenses. However, when the draw period ends, you can no longer borrow, and your payment increases significantly as you begin repaying the principal over the repayment period (typically 10-20 years).
Exploring home financing options? Check out our mortgage recast calculator and borrowing power calculator.
Get Custom Calculator for Your PlatformResult: Payment increases from $625/month to $805/month (+29%)
Total interest paid over 30 years: $168,200. Consider paying principal during draw period to reduce future payments.
$100K, 10-year repayment period
$1,207/mo (+93% increase)
$100K @ 10% interest
$833/mo draw, $965/mo repayment
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