About & methodology

What this is

Nest Egg Math teaches the math behind financial decisions instead of issuing a recommendation. Every lesson is built the same way: a real, working example loads immediately, every assumption behind it is visible, and every one of those assumptions is a lever you can drag. The bet is that people understand a relationship — how a mortgage rate or a rent increase changes an outcome — by manipulating it, not by reading someone's conclusion about it.

What it isn't

These tools compute — they don't advise. Nest Egg Math doesn't ask who you are, doesn't tailor a recommendation to your specific situation, and doesn't tell you to buy, sell, or hold anything. The buy-vs-rent lesson, for example, is built so it can honestly say "rent" as easily as it says "buy" — a tool that always says one or the other is an ad wearing a calculator's clothes. There's no signup, and it's free: no ads tied to the outcome of any calculation, no affiliate links, no sponsored placements in the math itself.

The buy-vs-rent model, specifically

Both sides of the comparison start with the same amount of cash. The buyer puts it toward a down payment and closing costs; the renter invests it instead, and keeps investing whatever renting leaves over in any month owning would have cost more. At the horizon you choose, the model compares total net worth: home equity net of selling costs and capital-gains tax (after the §121 primary-residence exclusion) plus any side investments, versus the renter's full invested balance.

It accounts for mortgage amortization, property tax and insurance (scaled with home value and general inflation), HOA, PMI while equity is under 20%, closing costs on both the purchase and the eventual sale, rent inflation, and the tax benefit of itemizing mortgage interest and property tax (capped at $10,000 under current law) when that beats the standard deduction. It does not account for a household's other itemizable deductions, so it's a fair read on housing's own tax effect but not a substitute for a full tax return.

Privacy

The numbers you enter into a lesson never leave your browser — there are no accounts, and nothing is stored anywhere but this device. See the Privacy page for the full detail, including how to see and delete what's saved.