HELOC Calculator: Draw, Repayment & Total Cost 2026

How a HELOC works

On the defaults — a $50,000 draw at 8.5% APR, a 10-year draw period and a 20-year repayment period — the draw payment is $354.17 a month (interest only), the draw-period interest is $42,500.00, the repayment payment is $433.91 a month, the repayment interest is $54,138.40, and the total interest across both phases is $96,638.40 on total paid of $146,638.40. The draw payment is the balance times the monthly rate: $50,000.00 × 8.5% ÷ 12 = $354.17. The draw interest is the balance times the APR times the draw years: $50,000.00 × 8.5% × 10 = $42,500.00. In repayment the same $50,000 is amortized over 240 months, which is why the repayment payment ($433.91) is higher than the draw payment even though the balance is the same — it has to pay the principal down as well as the interest.

The worked example, line by line

Setup: balance drawn $50,000.00, APR 8.5%, draw period 10 years, repayment period 20 years.

Line 1 — the monthly rate. 8.5% ÷ 12 = 0.708333% a month.

Line 2 — the draw payment. $50,000.00 × 0.708333% = $354.17 a month, interest only.

Line 3 — the draw-period interest. $50,000.00 × 8.5% × 10 years = $42,500.00.

Line 4 — the repayment payment. $50,000.00 amortized over 240 months at 0.708333% a month = $433.91 a month.

Line 5 — the repayment total and interest. $433.91 × 240 = $104,138.40 paid in repayment, of which $54,138.40 is interest.

Line 6 — the totals. Total interest $42,500.00 + $54,138.40 = $96,638.40; total paid $42,500.00 + $104,138.40 = $146,638.40. Rounding convention: totals are computed from rounded payment figures, so rounded parts may differ by a cent from their rounded sum.

Every branch, checked

Balance $25,000: draw $177.08/mo, draw interest $21,250.00, repay $216.96/mo, total interest $48,320.40. Halving the balance halves every figure — the model is linear in the balance.

Balance $100,000: draw $708.33/mo, draw interest $85,000.00, repay $867.82/mo, total interest $193,276.80. Doubling the balance doubles the interest in dollars, but the payments per dollar do not change.

APR 7%: draw $291.67/mo, draw interest $35,000.00, repay $387.65/mo, total interest $78,036.00. A point and a half less APR saves $18,602.40 of total interest on the same $50,000.

APR 10.5%: draw $437.50/mo, draw interest $52,500.00, repay $499.19/mo, total interest $122,305.60. Two points more APR adds $25,667.20 of total interest — the APR is the lever that matters most.

Draw period 5 years: draw $354.17/mo, draw interest $21,250.00, repay $433.91/mo, total interest $75,388.40. Halving the draw period halves the draw interest; the repayment payment does not change, because the balance entering repayment is still $50,000.

Repayment period 10 years: draw $354.17/mo, draw interest $42,500.00, repay $619.93/mo, total interest $66,891.60. Halving the repayment period raises the monthly payment by $186.02 but cuts the repayment interest by $29,746.80.

The reverses, worked backwards

APR for a $500 draw payment: 12.00% — exact, because $50,000.00 × 12% ÷ 12 = $500.00. At 12.00% the repayment payment is $550.54; at 11.99% the draw payment is $499.58. The star is a PERCENT.

Smallest balance for a $300 draw payment: $42,352.95 — the exact unrounded balance is $42,352.9412. At $42,352.95 the draw payment is $300.00; one cent less, $42,352.94, gives an unrounded draw payment of $299.99999 — just below $300, even though it displays as $300.00 after rounding. The star is DOLLARS (balance).

Repayment months for a payment of $500 or less: 175 months (14.58 years) — at 175 months the repayment payment is $499.37; at 174 months it is $500.82. The star is MONTHS.

APR for a repayment payment of $450 or more: 9.01% — at 9.01% the repayment payment is $450.18; at 9.00% it is $449.86. The star is a PERCENT.

Draw months for $25,000 of draw interest: 71 months — at 71 months the draw interest is $25,145.83; at 70 months it is $24,791.67. The star is MONTHS.

Smallest balance for $100,000 of total interest: $51,739.23 — at $51,739.23 the total interest is $100,001.52; one cent less, $51,739.22, the total interest is $99,999.12. The star is DOLLARS (balance).

What the defaults assume

The draw payment is interest only — the balance does not fall during the draw period, so the balance entering repayment is the full amount drawn; the APR is held fixed across both phases, but most HELOCs are variable-rate, so a real line’s payments move with the prime rate; the model does not include annual fees, draw fees, minimum draw amounts, or a minimum monthly payment; it does not model further draws during the draw period. At 0% APR the draw payment is $0.00 and the repayment payment is $208.33 ($50,000.00 ÷ 240), and the total interest is -$0.80 — a rounding artifact, because 240 × $208.33 = $49,999.20, eighty cents short of the $50,000.00 principal. With a $0 balance every figure is $0.00. With a 0-year draw period the draw interest is $0.00 and the total interest is $54,138.40 — repayment only. With a 1-year repayment period the repayment payment is $4,360.99 and the repayment interest is $2,331.88. At 20% APR the draw payment is $833.33 and the repayment payment is $849.41. Rounding convention: totals are computed from rounded payment figures, so rounded parts may differ by a cent from their rounded sum; the reverses are smallest-value solutions, and the exact unrounded figures (12.00%, $42,352.9412, $299.99999, 175 months, 9.01%, 71 months, $51,739.23) are stated wherever the rounded figures appear.

Output · formula · meaning

Who uses this

• The homeowner weighing a $50,000 draw: they learn the draw payment is $354.17 a month and the total interest is $96,638.40 — and they check the 10-year repayment branch ($619.93 a month, $66,891.60 of interest) to see what a shorter repayment buys.
• The borrower who needs the draw payment under $500: they learn the APR has to be 12.00% or less for a $500 draw payment on $50,000 — and they check the 7% branch to see what a lower rate saves.
• The borrower sizing the balance: they learn $42,352.95 is the smallest balance with a $300 draw payment — and they check the $25,000 branch to see the payments on a smaller draw.
• The borrower planning the long run: they learn $51,739.23 is the smallest balance whose total interest passes $100,000 — and they check the 71-month reverse to see how fast draw interest reaches $25,000.

Accuracy & limitations

The math is first-principles: the draw payment is the balance times the monthly rate, the draw interest is the balance times the APR times the draw years, and the repayment payment is the standard amortization formula on the same balance over the repayment months — every figure is rounded to cents half-up, and the reverses are smallest-value solutions with the exact unrounded figures ($42,352.9412, $299.99999) stated wherever the rounded figures appear. What the model cannot do is predict YOUR HELOC bill: most HELOCs are variable-rate, so the APR moves with the prime rate and the payments move with it — this calculator holds one rate fixed across both phases. It does not model annual fees, draw fees, minimum draws, minimum monthly payments, further draws during the draw period, or the tax treatment of the interest. Use it to size the two phases, then read your lender’s disclosure for the fees and the rate rules.

Frequently asked questions