Abel's Calculators

Built by a dog, for humans

We factor in more than the others.

Most financial calculators online give you a number. We give you the full picture — modeling the real variables that shape your net worth: taxes, investment opportunity cost, equity, PMI, break-even timing, and more. Because a decision that looks obvious on a basic calculator can look very different when the math is actually complete. Abel is a dog and he knows this.

Your Current Loan

Original Loan Amount ($)

Interest Rate (%)

Original Term (months)

Remaining Term

years

months

Remaining Balance (calculated)

—

This is the balance that would be refinanced today

Home Value ($)

PMI Rate (%/yr)

Applied when LTV > 80%

Current Loan Extra Payment ($/mo)

Extra principal paid monthly — shortens payoff and builds equity faster

ARM / Rate Adjustment (optional)

new rate

starting year

If your rate adjusts (ARM), enter the adjusted rate and the year it kicks in. Leave blank for fixed.

Shared Settings

Marginal Tax Rate (%)

Capital Gains Rate (%)

Deductible Loan Balance Cap ($)

IRS caps deductibility at $750k for loans after 12/15/2017

Filing Status

2025 standard deduction used

Other Itemized Ded. ($/yr)

SALT, charitable, etc.

Portfolio Return — nominal (%)

Project N Years

Use a nominal (not inflation-adjusted) return — e.g. 8% for a broad stock index, which implies ~5% real at 3% inflation. This keeps the math consistent: your mortgage payments are fixed nominal dollars, so the portfolio must be in the same units. Both scenarios are compared in nominal dollars, so the difference between them is still meaningful even though the absolute figures grow with inflation. Every dollar not spent on your mortgage goes into this portfolio — payment savings, interest tax savings, and freed-up cash after payoff. Closing costs and extra paydown are treated as money pulled out on day one.

⌗

Configure your scenarios and hit Calculate

Each scenario compares that refi option vs. keeping your current loan,
measured as net worth impact (equity + investments) year by year.

Leave Feedback

Have a suggestion, found a bug, or just want to say something? We'd love to hear it. Name and email are optional.