ganak.appHELOC Calculator
Free HELOC calculator with draw and repayment periods. See interest-only vs P&I payments, payment shock warning, amortization schedule, and rate sensitivity analysis.
Equity Check (Optional)
Draw Period Payment
$354/mo
Repayment Payment
$434/mo
Payment Shock Warning
Your monthly payment will increase by $80 (23% increase) when the draw period ends. Budget for this transition to avoid financial strain.
Cost Breakdown
Total borrowing cost over the full 30-year term
Equity Check
Based on 85% max CLTV
You likely qualify
Available equity: $140,000 | CLTV: 62.5%
Current LTV
50.0%
CLTV with HELOC
62.5%
Rate Sensitivity
How rate changes affect your payment
| Rate | Draw | Repayment | Total Interest |
|---|---|---|---|
| 8.5% (current) | $354 | $434 | $96,639 |
| 9.5% | $396 | $466 | $109,356 |
| 10.5% | $437 | $499 | $122,306 |
| 11.5% | $479 | $533 | $135,472 |
Balance Over Time
Remaining balance, cumulative principal & interest paid
Amortization Schedule
Year-by-year breakdown of payments, principal, interest, and remaining balance
| Year | Phase | Payments | Principal | Interest | Balance |
|---|---|---|---|---|---|
| 1 | Draw | $4,250 | $0 | $4,250 | $50,000 |
| 2 | Draw | $4,250 | $0 | $4,250 | $50,000 |
| 3 | Draw | $4,250 | $0 | $4,250 | $50,000 |
| 4 | Draw | $4,250 | $0 | $4,250 | $50,000 |
| 5 | Draw | $4,250 | $0 | $4,250 | $50,000 |
| 6 | Draw | $4,250 | $0 | $4,250 | $50,000 |
| 7 | Draw | $4,250 | $0 | $4,250 | $50,000 |
| 8 | Draw | $4,250 | $0 | $4,250 | $50,000 |
| 9 | Draw | $4,250 | $0 | $4,250 | $50,000 |
| 10 | Draw | $4,250 | $0 | $4,250 | $50,000 |
What Is a HELOC?
A revolving credit line secured by your home equity
A Home Equity Line of Credit (HELOC) lets you borrow against your home's equity — the difference between market value and mortgage balance — up to an approved limit. Unlike a lump-sum home equity loan, a HELOC is revolving: borrow, repay, and re-borrow during the draw period.
5-10 years — borrow as needed, interest-only minimums
10-20 years — pay principal + interest, no new draws
Prime rate + margin, adjusts monthly or quarterly
Requires 15-20% equity, max 80-85% CLTV
How to Calculate HELOC Payments
Formulas for both draw and repayment phases with a worked example
Interest-Only (Draw Period)
Monthly Payment = Balance × (APR / 12)
Fully Amortizing (Repayment Period)
M = P × [r(1+r)ⁿ] / [(1+r)ⁿ - 1]
M = Monthly payment
P = Remaining balance
r = Monthly rate (APR/12/100)
n = Repayment months
Worked Example
Inputs
Results
How HELOC Interest Is Calculated
Daily interest accrual and how variable rates affect your cost
Daily Interest = Balance × (APR / 365)
Your monthly charge is the sum of daily interest for that billing cycle. Payments made early in the cycle reduce your daily accrual immediately — unlike fixed-rate mortgages where interest is calculated monthly.
A 1% rate increase on a $50,000 balance adds ~$42/month. A 3% increase adds ~$125/month. Use the rate sensitivity table above to stress-test your budget.
Understanding Payment Shock
The payment jump when draw period ends and repayment begins
$75,000 HELOC at 9% — 10-year draw, 15-year repayment
Draw Payment
$562
Repay Payment
$761
Shock
+35%
With interest-only draws on larger balances, payment shock can exceed 100%. Strategies to reduce it: make voluntary principal payments during draw, choose P&I from the start, or refinance before repayment begins.
How to Use This HELOC Calculator
5 steps to estimate your payments and total borrowing cost
Enter HELOC amount and rate
Set the amount you plan to borrow and the current APR. Typical rates range from 7-10%.
Set draw and repayment periods
Common configurations: 10/20, 10/15, or 5/20 year splits.
Choose interest-only or P&I during draw
Interest-only minimizes draw cost but maximizes payment shock.
Check your equity qualification
Enter home value and mortgage balance. Most lenders require CLTV of 85% or less.
Review results and rate scenarios
See both phase payments, shock warning, cost breakdown, and +1% to +3% rate impact.
HELOC vs Home Equity Loan
Choosing the right home equity product
| Feature | HELOC | Home Equity Loan |
|---|---|---|
| Rate | Variable (prime + margin) | Fixed for full term |
| Disbursement | Revolving — draw as needed | Lump sum at closing |
| Payments | Interest-only then P&I | Fixed P&I from day one |
| Flexibility | High — borrow/repay/re-borrow | None — fixed amount |
| Best For | Ongoing renovations, expenses | One-time cost, consolidation |
| Risk | Payment shock + rate increases | Predictable, no shock |
HELOC Qualification Requirements
What lenders look for when approving a home equity line of credit
Home equity of at least 15-20%
CLTV (mortgage + HELOC / home value) must be 80-85% or less.
Credit score of 680+
700+ earns the best rates. Score directly affects your prime + margin.
DTI ratio below 43%
Total debts including HELOC / gross income. Some allow up to 50%.
Stable income verification
Pay stubs, W-2s, or 2 years of tax returns for self-employed.
Common HELOC Mistakes
Pitfalls to avoid when using a home equity line of credit
Budget for both phases before committing
Secured by your home — missed payments risk foreclosure
A 2-3% jump adds hundreds to your monthly payment
Borrow only what you need, keep a buffer
Only deductible if used to improve the securing home
Frequently Asked Questions
Common questions and detailed answers
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Last updated Mar 22, 2026