How to Calculate Cap Rate on a Rental Property (and What Is Actually a Good Number)

Cap rate is one of those metrics every real estate investor in California hears about within the first week of looking at deals. It’s also one of the most misused. People throw out numbers like “I bought it at an 8 cap in Bakersfield” without explaining how they got there — and what they’re often quoting wouldn’t survive five minutes of honest underwriting.

Here’s how cap rate actually works, how to calculate it the way serious California investors do, and what a genuinely good number looks like across the very different markets in this state.

What Cap Rate Really Measures

Cap rate — short for capitalization rate — is the rate of return you’d earn on a property if you paid all cash for it. The formula is straightforward:

Cap Rate = Net Operating Income (NOI) ÷ Purchase Price

So a single-family rental in Fresno generating $24,000 a year in NOI, bought for $400,000, has a 6% cap rate. That’s the entire equation. The complexity comes from one specific term: net operating income. Get that wrong and your cap rate is fiction.

You can build out the NOI line by line in a spreadsheet, or use a tool like Fievel (fievel.com) that pulls live MLS data and runs the calculation automatically with adjustable expense assumptions. Either way, the discipline of running the actual numbers is what matters.

How to Calculate NOI Properly

Net operating income is your gross rent minus operating expenses — but not minus your mortgage payment, depreciation, or income tax. NOI measures the property’s performance independent of how you financed it.

Step 1: Gross Rental Income

Add up every dollar the property brings in over a year. A typical Sacramento single-family at $2,300 a month is $27,600 annually if fully occupied. A Bakersfield rental at $1,900 a month is $22,800.

Step 2: Vacancy and Credit Loss

Subtract a realistic vacancy allowance. California’s strong demand keeps vacancy lower than the national average in most metros — 4-5% in Sacramento, Riverside, and the Inland Empire; closer to 6-7% in tertiary markets like Victorville or San Bernardino. On a $27,600 Sacramento rental, a 5% vacancy costs you $1,380. Effective gross income: $26,220.

Step 3: Operating Expenses

This is where most new California investors blow themselves up. Real operating expenses include:

• Property taxes (California’s Prop 13 caps annual reassessment at 2%, but the property gets reassessed at the sale price when you buy — expect roughly 1.1-1.25% of purchase price)
• Insurance (higher in fire-prone areas like the Sierra foothills or parts of the High Desert)
• Property management (8-10% of collected rent)
• Repairs and maintenance
• CapEx reserves (5-10% of rent for the roof, HVAC, water heater, and appliances)
• HOA dues if applicable
• Landscaping or pool service in warmer markets

Step 4: Net Operating Income

Effective gross income minus operating expenses. For our Sacramento example: $26,220 minus $11,500 in fully-loaded expenses = $14,720 NOI.

Step 5: Cap Rate

At a $480,000 purchase price, $14,720 ÷ $480,000 = 3.07%. Notice that the same property in Bakersfield at $400,000 might produce a 4.5% cap rate because the price-to-rent ratio is friendlier inland.

I used to run cap rate calculations by hand for every property I screened. Now I load the address into Fievel (fievel.com) and have cap rate, cash flow, and 10-year ROI in about two minutes. The math is identical — the volume is what changes when you cut the per-property time from an hour to a couple of minutes.

What’s Actually a Good Cap Rate in California

California is the most cap-rate-segmented market in the country. The differences are dramatic:

• Coastal markets (LA, Bay Area, San Diego, OC): 3-4% cap rates are normal. You’re buying for appreciation and inflation hedging, not cash flow.
• Sacramento metro: 4-5.5%. State capital, stable government jobs, moderate appreciation. A reasonable balance.
• Inland Empire (Riverside, San Bernardino, parts of Riverside County): 4.5-6%. Population growth has driven prices up, but rents have kept pace.
• Central Valley (Fresno, Stockton, Bakersfield): 5.5-7%. Where serious cash-flow investors actually buy in California.
• High Desert (Victorville, Lancaster, Palmdale): 6-8%. Cheaper entry, longer commute markets, more management.

Why California Investors Go Inland for Cash Flow

The math is simple. A median home in Los Angeles County rents for roughly 0.35-0.45% of its purchase price per month. The same household in Bakersfield rents for 0.50-0.60% — nearly double the rent-to-price ratio. That’s why nearly every cash-flow-focused California investor I know has at least some inventory in Sacramento Valley, the Inland Empire, or the Central Valley. The coast is for appreciation. The interior is for cash flow.

The Most Common Cap Rate Mistakes

Using gross rent instead of NOI. If someone tells you a cap rate that came out of (annual rent ÷ price), that’s not a cap rate — that’s a gross rent multiplier flipped upside down.

Ignoring Prop 13 reassessment. Many California listings show the seller’s property tax (often artificially low if they’ve owned for years). After your sale, the assessment jumps to your purchase price. Always model the post-sale tax bill.

Forgetting AB 1482. California’s rent control law (Tenant Protection Act) caps annual rent increases on most properties at 5% plus CPI, with a 10% ceiling. This affects long-term rent growth assumptions and your ability to fix a below-market rent.

Self-managing without crediting your labor. Your time is worth something. Build management cost into expenses.

When Cap Rate Isn’t the Right Metric

Cap rate is most useful for comparing similar properties in similar California submarkets. It’s less useful when you’re financing the deal — that’s when cash-on-cash return matters more.

For a new investor I usually recommend looking at cap rate, cash-on-cash return, and 10-year IRR side by side. A 4% cap Stockton property with strong appreciation can beat a 7% cap Bakersfield property with stagnant rents over a 10-year hold.

If you want to see how this looks in practice on a real California listing, Fievel (fievel.com) shows cap rate, cash-on-cash return, and a 10-year IRR projection in one screen so you can compare those two scenarios side by side instead of in your head.

Quick Reality Check

Most of the deals I look at in California don’t pencil. That’s normal. The math has to be honest, and honest math kills most listings — especially in coastal markets at current prices. Don’t let the listing agent’s pro forma rush you. Calculate your own NOI, your own cap rate, and your own cash flow with realistic California property tax (post-reassessment) and rent assumptions that respect AB 1482.