Knowing how to buy a rental property is one thing… but do you actually know if it’s profitable?
Far too many brand-new landlords think they’re sitting on a gold mine, but once you deduct the real costs, the kind too many “gurus” fail to mention, you might just be breaking even. Or worse… losing money every single month without realizing it.
The good news? Learning how to calculate cash flow is simple once someone walks you through it like a friend, not a finance professor.
Most people throw this term around like confetti at a wedding, but let’s nail down what cash flow really means in rental real estate.
Cash flow is simply the money left over after all your expenses are paid.
If you collect $1,500 in rent and spend $1,200 each month on mortgage, insurance, maintenance, and property management, you’ve got $300 in positive cash flow. That’s your profit, your cushion, your monthly income stream.
If the opposite is true, and your costs are greater than your rent? You’re “cash flow negative,” which no investor wants to hear unless they’re banking big-time on appreciation (and even then, it’s risky).
Let’s break down the real numbers…
Here’s a simple formula you can use to calculate monthly cash flow on any rental:
Cash Flow = Gross Rental Income – Operating Expenses – Mortgage Payment
Now let’s break those terms down because this is where new investors get tripped up:
Gross Rental Income: This is the total amount of rent you receive per month. If you rent for $1,600/month and your tenant actually pays on time, that’s it. However, you should budget for some vacancy. A common rule of thumb is to reduce it by 5-10% to account for the months it’s unoccupied.
Operating Expenses: Here’s where people underestimate. This includes:
- Property taxes
- Insurance
- Maintenance (set aside 5-10% of rent monthly)
- Capital expenditures (repairs and replacements: think roof, HVAC, appliances)
- Property management fees if you hire out
- HOA fees (if applicable)
Mortgage Payment: This is your monthly P&I (principal and interest), NOT including taxes or insurance if you already counted them.
Let’s take a look at a real life example…
Let’s say you recently picked up a single-family home for $200,000 and put 20% down. Your mortgage might be $1,073/month (assuming a 7% rate over 30 years). You charge $1,700/month in rent.
Now let’s estimate your costs:
Mortgage: $1,073
Property Taxes: $150
Insurance: $100
Maintenance: $100 (this is ~6% of rent)
Vacancy Reserve: $85 (5% of rent)
CapEx: $100
Total Operating Expenses (not counting mortgage): $535
Now let’s calculate your cash flow:
Gross Rent: $1,700
– Operating Costs: $535
– Mortgage: $1,073
= Cash Flow: $92/month
You’re making $92 per month in actual profit. Not bad, but not the windfall some “guru” investors pretend it is. The key is to be realistic about your expenses so you don’t end up with unexpected surprises later.
If that $92 sounds a little low for your liking, there are a few ways to increase your cash flow:
You can negotiate your purchase price… The lower your mortgage, the better your cash flow.
You can add value… A renovated kitchen or bathroom lets you justify higher rent.
You can self-manage… If you’re local and handy, skip the property manager and pocket the 8-10% fee.
You can optimize rent… Many beginner landlords undercharge. Run comps and adjust accordingly.
Remember: $92 a month might not feel like a windfall, but multiply that by 3 properties and you’re pulling in an extra $276 a month. Go to 5 properties, now you’re clocking in at $460/month… that’s a car payment covered.
Real estate is a game of scale built on smart math.
Cash flow isn’t some mystical concept… it’s simple math.
Maybe your brain doesn’t light up at spreadsheets, but if you can add and subtract, you can figure this out. Just remember to account for every cost, even the ones that don’t happen every month (like replacing a busted water heater).
If the property gives back every single month without draining your wallet… congratulations, you’ve earned a real, income-generating asset. Just rinse and repeat as you grow.
