Model two lines with clear inputs fast. Compare draw periods, margins, and closing fees easily. Pick the option that fits your monthly budget best.
A simple reference dataset showing how differences in margin and fees can affect total cost.
| Scenario | Home Value | Mortgage | Amount | Index | Margin A | Margin B | Closing A | Closing B |
|---|---|---|---|---|---|---|---|---|
| Sample | $350,000 | $210,000 | $50,000 | 5.50% | 1.50% | 2.00% | $450 | $650 |
| Lower Fees | $350,000 | $210,000 | $50,000 | 5.50% | 1.75% | 1.90% | $0 | $0 |
| Shorter Term | $350,000 | $210,000 | $35,000 | 5.50% | 1.50% | 2.00% | $450 | $650 |
When two lines look similar, total cost is usually driven by rate structure, fees, and how long you carry a balance. A higher margin can add interest even if the offer feels close. On a $50,000 balance, a 0.50% higher rate is roughly $250 more interest per year. Closing costs and annual fees act like fixed charges and matter more on smaller balances or shorter timelines.
This calculator estimates an available line using home value, your current mortgage balance, and a target combined loan-to-value (CLTV). For example, a $350,000 home with an 85% CLTV and a $210,000 mortgage suggests about $87,500 of remaining room. Lenders may use different limits, so treat this as a planning range.
During the draw period, many lines allow interest-only payments, estimated as Principal × (Rate ÷ 12). If you draw $50,000 at 7.0%, the initial monthly interest is about $291.67. After the draw ends, the repayment period typically amortizes the balance, so the monthly payment rises as principal is paid down. A 15-year repayment at 8.0% is roughly $478 per month on $50,000, excluding fees.
For variable pricing, the tool models a yearly rate path using an expected annual change and a lifetime cap. If rates climb 0.50% per year with a 4.00% cap, a 7.0% start rate can reach 11.0% at the cap. Use the chart to compare how each option reacts to rising rates.
Review total interest, total fees, and total cost side by side, then check the highest estimated monthly payment to gauge budget impact. If total costs are within a small range, the lower peak payment can be the safer choice. Also consider flexibility: lower fees can help if you plan to repay early, while a lower margin can help if the balance stays outstanding. Export CSV or PDF to discuss scenarios with your lender or advisor.
1) Why does the draw payment look lower than the repayment payment?
During the draw phase, many lenders allow interest-only payments, so you may pay only interest on the balance. When repayment begins, payments usually include principal, which increases the monthly amount.
2) What does “index + margin” mean?
The index is a reference rate used by the lender. The margin is the lender’s add-on. Your variable rate is typically the index plus the margin, unless an introductory rate applies.
3) How does the cap affect the comparison?
A lifetime cap limits how far the variable rate can rise from its starting level. If two offers have different caps, the higher cap can create more risk and potentially higher interest costs over time.
4) Are fees really that important?
Yes. Closing costs and annual fees act like fixed costs. They matter most for smaller balances, short holding periods, or when you plan to repay early, because you have fewer months of interest to “dilute” fees.
5) Can I compare different draw and repayment terms?
Absolutely. Enter each offer’s draw years and repayment years exactly as disclosed. Different structures can change cash flow dramatically even when rates are similar, especially when repayment starts.
6) How accurate are the variable-rate estimates?
They are planning estimates. The chart uses your assumed annual change and cap, but real pricing can move unevenly and may include floors, periodic caps, or minimum payment rules. Use this to compare scenarios, not to predict exact bills.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.