Home Equity Tool

HELOC Interest-Only Calculator - Home Equity Line Payment Calculator

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: January 10, 2025

Draw period and repayment period analysis
Payment increase (payment shock) calculation
Total interest and LTV ratio assessment

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HELOC Interest-Only Calculator
Calculate HELOC payments during interest-only draw period and repayment phase

Used to calculate loan-to-value ratio

Payment Analysis

Interest-Only Payment (Draw Period)Years 1-10

$625.00/mo

Total interest: $75,000

Principal + Interest (Repayment Period)Years 11-30

$805.59/mo

Total repayment: $193,342

Payment Increase

+28.9%

Payment increases by $180.59/month

Total Interest Paid

$168,342

Loan-to-Value

25.0%

Remaining Home Equity

$300,000

Yearly Payment Breakdown (First 10 Years)

Year 1
$625/moPrincipal: $0Interest: $7,500
Year 2
$625/moPrincipal: $0Interest: $7,500
Year 3
$625/moPrincipal: $0Interest: $7,500
Year 4
$625/moPrincipal: $0Interest: $7,500
Year 5
$625/moPrincipal: $0Interest: $7,500
Year 6
$625/moPrincipal: $0Interest: $7,500
Year 7
$625/moPrincipal: $0Interest: $7,500
Year 8
$625/moPrincipal: $0Interest: $7,500
Year 9
$625/moPrincipal: $0Interest: $7,500
Year 10
$625/moPrincipal: $0Interest: $7,500

HELOC Interest-Only Calculator Features

Draw Period Payment Calculator
Calculate interest-only payments during draw period

Typical period

10 Years

Interest-only payments on outstanding balance

Repayment Period Calculator
Calculate principal + interest payments after draw period

Typical period

10-20 Years

Fully amortizing principal and interest payments

Payment Shock Calculator
Calculate payment increase from draw to repayment period

Typical increase

100-300%

Significant payment increase when principal repayment begins

Total Interest Calculator
Calculate lifetime interest cost of HELOC

Interest components

Draw + Repayment

Total interest paid over entire loan term

Loan-to-Value Calculator
Calculate HELOC LTV ratio and available equity

Typical max

80-85% CLTV

Combined loan-to-value including first mortgage

HELOC Amortization Schedule
Year-by-year payment and balance breakdown

Shows details

Principal & Interest

Yearly breakdown of payments and remaining balance

Quick Example Result

$100,000 HELOC at 7.5% with 10-year draw and 20-year repayment:

Draw Payment

$625

Repayment

$806

Increase

+29%

Total Interest

$168K

How Our HELOC Interest-Only Calculator Works

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.

HELOC Payment Calculation Formulas

Draw Period (Interest-Only):
Monthly Payment = Balance × (Annual Rate ÷ 12)
Example: $100,000 × (7.5% ÷ 12) = $625/month
Repayment Period (Principal + Interest):
Payment = Balance × [r(1+r)^n] / [(1+r)^n - 1]
Where r = monthly rate, n = months in repayment period
Example: $100,000 over 20 years at 7.5% = $805/month

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.

📊 HELOC Payment Timeline

Visualization of payment structure across draw and repayment periods

Understanding HELOC Structure

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).

  • Draw period: Borrow/repay flexibility, interest-only payments, typically 10 years
  • Repayment period: No new borrowing, principal + interest, typically 10-20 years
  • Variable rate: Most HELOCs tied to prime rate, payments fluctuate with rate changes
  • Payment shock: Transition to repayment can double or triple monthly payment
  • Tax deduction: Interest may be deductible if used for home improvements
  • Foreclosure risk: Your home secures the loan—default can result in foreclosure

Sources & References

  • Consumer Financial Protection Bureau (CFPB) - What is a HELOC?Official consumer guidance on home equity lines of credit
  • Truth in Lending Act (TILA) - Regulation ZFederal regulations governing HELOC disclosure requirements
  • IRS Publication 936 - Home Mortgage Interest DeductionTax rules for HELOC interest deductibility

HELOC Interest-Only Calculator Examples

HELOC Payment Calculator Example
Calculate payments for $100,000 HELOC at 7.5% interest

HELOC Terms:

  • HELOC Amount: $100,000
  • Interest Rate: 7.5% (variable)
  • Draw Period: 10 years
  • Repayment Period: 20 years
  • Home Value: $400,000
  • LTV: 25%

Payment Calculation:

  1. Draw payment: $100,000 × (7.5% ÷ 12) = $625/mo
  2. Draw period total: $625 × 120 months = $75,000
  3. Repayment: $100K @ 7.5% over 20 yrs = $805/mo
  4. Repayment total: $805 × 240 months = $193,200
  5. Total interest: $75,000 + $93,200 = $168,200
  6. Payment increase: $805 - $625 = +$180 (29%)

Result: 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.

Shorter Repayment Example

$100K, 10-year repayment period

$1,207/mo (+93% increase)

Higher Rate Example

$100K @ 10% interest

$833/mo draw, $965/mo repayment

Frequently Asked Questions

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