Real Estate Cash Flow Calculator

Comprehensive real estate cash flow calculator including capex reserve - the often-forgotten line that separates accurate from optimistic projections. Capex reserve (5-10% of effective gross income) covers major expenses (roof, HVAC, kitchen) that don't show in monthly numbers but eventually crush returns if ignored.

Example: 24k gross rent annual, 5% vacancy = 22.8k effective gross. 8k operating expenses, 1.14k capex reserve (5%), 14k debt service = £-340 annual cash flow. Tight margin even before factoring full capex reality (replacing roof every 25 years = 15k = 600/year amortised). Many 'positive cash flow' rentals show losses once full capex captured.

Operating expenses to include: property management (8-12% of gross), maintenance (5-10%), property taxes, insurance, HOA/service charges, utilities (if landlord-paid), marketing/turnover costs. Capex reserve covers 'big ticket' items: roof (25-year life, 4% per year), HVAC (15-year, 7%), kitchen/bath remodels (15-25 year, 4-7%), exterior paint (10-year, 10%), water heaters (10-year, 10%). 5-10% of EGI is conservative starting point.

Quick example

With annual gross rent of 24,000 and vacancy of 5% (plus annual operating expenses of 8,000 and annual debt service of 14,000), the result is -340.00. Change any figure and watch the output shift — it's often more useful to see the pattern than to memorise the formula.

Which inputs matter most

You enter Annual Gross Rent, Vacancy %, Annual Operating Expenses, Annual Debt Service, and Capex Reserve %. Not every input has equal weight. Adjusting one input at a time toward extreme values shows which ones move the result most.

What's happening under the hood

Effective gross - operating expenses - capex reserve - debt service. The formula is listed in full below. If the number looks off, you can retrace the calculation by hand — that's the point of showing the working.

Why investors run this

Most people's intuition for compounding is wrong — not because the math is hard, but because linear thinking doesn't account for curves. Running numbers through a calculator like this one is the cheapest way to recalibrate that intuition before making an irreversible decision about contribution rate, asset mix, or retirement age.

What this doesn't capture

Steady-rate math ignores real-world volatility. Actual returns are lumpy; sequence-of-returns risk matters most in drawdown; fees and taxes drag on compound growth; and behaviour changes in drawdowns can reduce outcomes below the projection. The number represents one scenario rather than a forecast.