The Best Free House Hacking Calculators in 2026

Every house hack comes down to one number: what you will actually pay each month to live in the property after the rent comes in. I ran that number over and over before buying my duplex. A spreadsheet works, but a good calculator is faster, and the free ones have gotten good enough that there is no reason to pay for software on your first deal.

Here are the free house hacking calculators worth your time in 2026, including one I built myself. I will be upfront about which is which.

What a house hacking calculator needs to get right

A house hack is not a normal rental, because you live in it. The number that matters most is your effective housing cost, meaning your full monthly payment minus the rent your tenants pay, with real expenses included. A calculator that skips vacancy and repairs will tell you a comfortable lie. The two lines beginners most want to zero out are the two that decide whether the deal survives a bad month.

Beyond that, you want cash flow and cash-on-cash return so you can compare one deal against another. If a tool gives you those three numbers from inputs you can find in a listing, it is doing its job.

The five calculators

1. VanToVault House Hacking Calculator

Full disclosure: this one is mine, so weigh that as you read. I built the free house hacking calculator because the tools I wanted while shopping for my duplex were locked behind accounts and paywalls. You enter the purchase price, down payment and loan terms, the rent the other unit could bring, and your taxes, insurance, and expenses. It returns your monthly payment, cash flow, cash-on-cash return, and your effective housing cost. Any site can embed it for free.

2. RentalRealEstate House Hacking Calculator

The simplest tool of the group. The RentalRealEstate house hacking calculator takes five inputs, your mortgage payment, taxes, insurance, other expenses, and tenant rent, and returns a single net housing cost figure. Free, no signup, and part of a suite of more than 40 rental calculators. It is a good 30-second gut check, though it is light on return metrics like cash-on-cash.

3. SparkRental House Hacking Calculator

The SparkRental house hacking calculator frames the question a little differently: it shows what share of your mortgage payment the rent will cover. It includes vacancy, maintenance, and property management in the math, which more tools should copy, and it returns both the coverage percentage and your net monthly housing cost. Free and no signup required.

4. BiggerPockets Rental Property Calculator

The most complete analysis tool of the group. The BiggerPockets rental property calculator produces cash-on-cash return, IRR, cap rate, and long-term projections, plus printable PDF reports you can hand a lender or a partner. It is built for standard rentals rather than house hacks, so it will not center your effective housing cost, and sustained use sits behind a Pro membership. I compared it to my own tool in more detail in a free BiggerPockets calculator alternative.

5. DealCheck

DealCheck is an app rather than a page, available on the web, iOS, and Android. It can import listing data, run rentals, BRRRR deals, flips, and small multifamily, and generate professional reports. There is a free plan to start and paid tiers for the full feature set. It is more than a first house hack needs, but if you end up analyzing deals every week, it earns a spot.

Tools that pair well with these

A calculator is only as good as the rent number you feed it. Check what the other unit could rent for with Rentometer or Zillow rent estimates, then confirm against actual local listings. For pure payment math with a clean amortization breakdown, the Calcuja mortgage calculator is a solid standalone tool.

How I would use them on a real deal

Estimate the rent first, since everything downstream depends on it. Run the quick read in my calculator or the RentalRealEstate tool to see whether the deal is even close. If it survives that, run the deeper numbers before making an offer, and compare the result against what a good cash on cash return looks like so you are not grading your own homework.

The tool matters less than the discipline of complete inputs, vacancy and repairs included. If you want to see that logic worked through an actual purchase, it is all in The Duplex Math, Line by Line.