HELOC Calculator
See your draw period payment and repayment period payment side by side, including the exact dollar increase when interest-only draws convert to full principal and interest.
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Enter your values above to see the results.
Tips & Notes
- ✓Budget for the repayment period payment from day one — the draw period interest-only payment dramatically understates your true monthly obligation over the full term.
- ✓HELOC rates are variable — a 2% rate rise during your draw period raises both the draw payment and the repayment period payment simultaneously.
- ✓Pay down principal during the draw period even though not required — every dollar paid reduces the repayment balance and the payment shock at conversion.
- ✓The credit limit on a HELOC can be frozen or reduced if your home value declines — never rely on it as a guaranteed emergency fund.
- ✓Shop HELOCs by the margin over prime (the fixed component), not the current rate — the margin is the permanent cost while the prime rate changes monthly.
- ✓Some lenders let you convert a HELOC balance to a fixed-rate loan during the draw period — useful when rates spike and you want payment certainty.
Common Mistakes
- ✗Planning your budget around the draw period interest-only payment without modeling what repayment will cost — the conversion catches many borrowers off guard.
- ✗Treating a HELOC as long-term financing when rates are rising — the variable rate can transform a comfortable draw payment into a strained repayment budget.
- ✗Drawing the full credit limit immediately rather than as needed — you pay interest on every dollar drawn, even if not yet productively deployed.
- ✗Confusing a HELOC with a home equity loan — HELOCs are revolving variable-rate lines; home equity loans are fixed-rate term loans with immediate P&I.
- ✗Using HELOC funds for depreciating purchases like vehicles or vacations — the interest is not tax-deductible for non-home-improvement uses under current law.
- ✗Not reading the draw period end date — many borrowers are surprised by the conversion because they never tracked when the interest-only period expires.
HELOC Calculator Overview
A HELOC (Home Equity Line of Credit) works in two phases that most borrowers dramatically underestimate. During the draw period, you pay interest only on what you borrow — payments feel manageable. During the repayment period, the full balance converts to principal-and-interest payments that can be 40-100% higher. Planning around this conversion is essential.
What each field means:
- Credit Line — maximum amount you can borrow; interest is charged only on what you actually draw
- Interest Rate — variable rate tied to prime; this rate changes when the Federal Reserve moves rates
- Loan Term — total HELOC term (draw period + repayment period combined)
- Down Payment — not applicable; HELOCs are lines of credit, not purchase loans
What your results mean:
- Monthly Payment — your draw period interest-only payment at the current rate on your full draw
- Total Paid — total payments over both draw and repayment periods
- Total Interest — all interest paid; higher than most borrowers expect due to repayment period
- Repayment payment — the significantly higher P&I payment that starts when the draw period ends
Example — $60,000 HELOC at 8.5%, 10-year draw + 15-year repayment:
Draw period payment (interest only on $60,000): $425/month Repayment period payment (P&I, 15 years): $591/month Payment jump at conversion: +$166/month (+39%) If rate rises to 10.0% by repayment start: Repayment payment: $644/month — jump: +$219/month from draw period Total interest over full 25-year HELOC: approximately $76,200
EX: $80,000 needed — HELOC vs home equity loan at current rates HELOC at 8.75% variable (10yr draw + 15yr repayment): Draw: ~$583/month | Repayment: ~$800-$900/month depending on future rates Total interest: ~$100,000+ — rate uncertainty is significant Home equity loan at 8.25% fixed (20-year term): Fixed payment: $686/month for 20 years — no surprises Total interest: $84,640 — certain and lower if rates rise Fixed loan wins on cost and certainty unless you need phased access to funds.
HELOC draw period payment by balance and rate (interest only):
| Balance Drawn | 7.0% | 8.5% | 10.5% |
|---|---|---|---|
| $20,000 | $117 | $142 | $175 |
| $40,000 | $233 | $283 | $350 |
| $60,000 | $350 | $425 | $525 |
| $80,000 | $467 | $567 | $700 |
Payment jump at HELOC conversion — $60,000 balance:
| Rate at Repayment | 15-year repayment | 20-year repayment | Jump from 8.5% draw |
|---|---|---|---|
| 7.0% | $539 | $465 | +$114 / +$40 |
| 8.5% | $591 | $521 | +$166 / +$96 |
| 10.5% | $662 | $600 | +$237 / +$175 |
HELOC rates move with the prime rate — when the Federal Reserve raises rates, HELOC payments rise within months. Borrowers who maxed their HELOC at 5% during low-rate environments found payments nearly doubling when the prime rate rose to 8.5%. Budget for the repayment period payment from the moment you open the line, not the draw period payment — it is the repayment payment that determines whether a HELOC is affordable over its full life.
Frequently Asked Questions
The draw period is when you can borrow against the credit line, repay, and reborrow — typically 5-10 years. Most HELOCs require only interest payments during this time. The repayment period follows — typically 10-20 years — during which no new borrowing is allowed and the full outstanding balance must be repaid through P&I payments. The total HELOC term is both periods combined. The critical point: the repayment payment is substantially higher than the draw period interest-only payment, especially if rates have risen during the draw period.
Most lenders require that total debt on the property — first mortgage plus HELOC — not exceed 80-85% of home value. With a $400,000 home and $280,000 mortgage (70% LTV), you might access a HELOC of $40,000-$80,000 (reaching 80-90% combined LTV). Your actual limit depends on the appraisal, credit score, and lender standards. Credit scores below 680 typically face tighter limits or denial. HELOCs are not available to recent buyers with small down payments until meaningful equity builds up.
HELOC interest is deductible on federal taxes only if funds are used to buy, build, or substantially improve the home securing the line — the IRS requirement since the 2017 Tax Cuts and Jobs Act. Interest on HELOC funds used for debt consolidation, education, or consumer spending is not deductible. Additionally, you must itemize deductions to claim mortgage interest deductions. With the higher standard deduction now in effect, most homeowners no longer itemize, making deductibility moot for the majority of borrowers.
Some lenders offer a fixed-rate advance or rate-lock feature that allows you to lock a portion of your outstanding HELOC balance into a fixed-rate loan during the draw period. This freezes the rate on that amount while the rest remains variable. It typically comes with a slightly higher rate than the current variable rate as the cost of certainty. Not all HELOC products include this feature — worth asking for when shopping, particularly if you plan to draw a large amount that you want to protect from rate increases.
Lenders can freeze or reduce your available credit limit if home value falls significantly, as permitted under standard HELOC terms when combined LTV exceeds certain thresholds. You receive notice that new draws are suspended, though existing balance payments continue normally. This happened to many borrowers during 2008-2010 — homeowners relying on HELOC availability as an emergency fund found access suspended when they needed it most. Always maintain a separate liquid emergency fund rather than relying on a HELOC for financial resilience.
A HELOC is better for phased or ongoing expenses — home renovations spread over 2-3 years, business working capital, or a flexible reserve. You borrow only what you need when you need it, minimizing interest cost. A home equity loan is better for a single large defined expense with a fixed cost. The fixed rate provides certainty and the payment starts immediately. If rates are rising, the home equity loan protects from increasing costs. If rates are stable or falling, the HELOC often costs less total interest because you borrow gradually.