Investment property ROI calculator.

Underwrite a Maryland rental or a flip the way Samantha runs her own deals — cap rate, cash-on-cash, the 1% rule, GRM, and net flip profit. Switch between Buy & Hold and Flip mode in one click.

Acquisition
$
$
%
$
$
Financing
%
yrs
Income (monthly)
$
% vac
% mgmt
Operating expenses (annual)
$
$
$
% rent
Annual cash flow $0 $0/mo · after debt service and reserves
Cap rate0.0%NOI / total project cost
Cash-on-cash0.0%annual cash flow / cash invested
GRM0.0price ÷ annual rent
1% rule0.00%monthly rent vs price

Monthly cash flow breakdown

Gross rent$0
− Vacancy$0
− Property mgmt$0
− Taxes$0
− Insurance$0
− HOA$0
− Maintenance reserve$0
− Mortgage P&I$0
Net monthly cash flow$0
Run the numbers above to see if this deal pencils.

How investors read these numbers.

The point of underwriting isn't precision — it's pattern recognition. Samantha runs hundreds of these spreads a year. Here's how she reads each metric.

Cap rate

Net operating income divided by total project cost. NOI is rent minus vacancy, management, taxes, insurance, HOA, and maintenance — but not debt service. Cap rate strips out financing so you can compare deals apples to apples. In the DMV, a 6% cap on a B-class single-family is solid; 8%+ usually means a value-add play in Baltimore City or Prince George's.

Cash-on-cash return

Annual cash flow divided by total cash invested (down payment + rehab + closing). This is the number that pays for your kid's college. With current rates, anything over 8% cash-on-cash on a stabilized rental is a good deal. Under 4% and you're betting entirely on appreciation.

GRM and the 1% rule

GRM (Gross Rent Multiplier) is price divided by annual rent — under 100 is generally healthy in the DMV. The 1% rule says monthly rent should be at least 1% of purchase price. Almost no DMV deal hits 1% anymore — Samantha looks for 0.65%+ on stabilized rentals and treats anything below 0.5% as appreciation play, not income property.

The 70% rule (flips only)

Maximum offer = (ARV × 70%) − rehab. It's a screening tool, not a hard rule. In Anne Arundel and Howard County the 70% rule is too tight — Samantha will sometimes take a deal at 75% if the comps are bulletproof and the rehab risk is contained. In Baltimore City she stays at 65% because resale risk runs higher.

For a real underwriting review on a specific Maryland property, request a consultation or see Samantha's active investment pipeline.

Want Samantha to underwrite a deal with you?

Send the address. She'll run rents, comps, and rehab in 24 hours and tell you straight whether it pencils — flip or hold.

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