NYC Affordability

Sourced vs. calculated

Every number on this site is one of two kinds, and pages label which is which:

• Cited figures come from somewhere else: a median rent from a broker report, a tax rate from the state, an income limit from HUD. Each carries its source and the period it describes. We don't round them into something tidier, and we don't invent one when no stable source exists. The citywide condo median, for example, says "Not yet tracked."
• Calculated figures are ours: your maximum rent, maximum purchase price, income needed, cash to close. They come from running cited figures and your inputs through the formulas described below. They're estimates, not quotes.

Laws, conventions, and our own guesses

Not every default deserves the same trust, so each one is tagged with what kind of number it is:

• Law or regulation: the mansion tax tiers, mortgage recording tax, transfer taxes, the $20 rental application fee cap, the one-month security deposit cap. These change only when the law does.
• Official data: the Freddie Mac mortgage rate (6.95%, survey week of September 17, 2026), HUD income limits, IRS and New York tax brackets.
• Market convention: the 40× rent rule, 80× for guarantors, a 28% co-op board DTI limit, 12 months of post-closing liquidity. Common, not universal. Your landlord or board can and will differ.
• Market survey: typical figures from broker and industry reports, like attorney fees and PMI pricing.
• Our estimate: a reasonable midpoint we chose so the calculator has something to start from, like $1,200/month co-op maintenance or $1,000/month condo common charges. Replace these with real numbers from the listing.

The full list, with every source and verification date, is on Sources & data status.

The binding constraint

"How much can I afford?" is really several questions, and the answer is whichever one says no first:

• Income (DTI): what a lender, board, or landlord will approve given your monthly housing cost plus other debts relative to gross income. For rentals this is usually the 40× rule.
• Down payment and closing costs: the cash you can put toward the purchase on closing day, including mansion tax, mortgage recording tax (condos), and fees.
• Reserves: for co-ops, the liquid assets the board wants left over after closing. Condos can include this optionally.
• Move-in cash: for rentals, first month, security deposit, fees, and any broker you hired yourself.

Each calculator computes every ceiling, reports the lowest as your maximum, and names the one that bound. That's usually more useful than the number itself: "your income supports more, but your savings don't" calls for a different plan than the reverse.

One engine, everywhere, in your browser

The co-op, condo, and rent math lives in one shared module. The calculators, the comparison dashboard, the Reality Check, and the pre-built income, salary, price, and neighborhood pages all run that same code with the same defaults, so the same inputs give the same answer on every page. Automated tests pin the tax tiers, the DTI and reserve math, and the defaults each calculator starts from.

All of it runs in your browser. Nothing you type is sent to a server, and the optional "Save inputs" toggle stores your numbers only in your own browser's local storage. The source code is public on GitHub ↗ if you'd like to check.

How defaults are reviewed, and what happens when data gets old

• There's no automatic refresh. Defaults are updated by hand when a source publishes something new, such as a new Freddie Mac survey or HUD's annual income limits.
• Each default records when it was last re-verified. Where no check is recorded, the sources page says "not yet re-verified" instead of showing a date we can't back up.
• Cited market figures keep their own as-of date, even when two numbers on the same page come from different months. We'd rather show you the real gap than pretend they were measured together.
• Every default is editable on its calculator. If you have a better number (the actual maintenance, your rate quote), use it.

Why your lender or co-op board may disagree

These calculators model the common case. Real approvals depend on things a calculator can't see:

• Lender overlays: credit score pricing, jumbo loan rules, stricter DTI caps, reserve requirements, and how they count bonus or self-employment income.
• Building rules: co-op boards set their own DTI limits, liquidity requirements, minimum down payments, and sublet and flip-tax policies. Some are much stricter than the defaults here.
• The specific unit: actual maintenance or common charges, tax abatements, assessments, appraisal, and the building's finances.
• Discretion: boards and landlords can say no for reasons that aren't in any formula.

Use the numbers here to plan and to ask better questions, then confirm with a licensed mortgage professional and a real estate attorney.

Found a mistake?

Tell us on the contact page or open an issue on GitHub ↗. Corrections to the math or a cited figure are noted in the project's change log on GitHub.