If you own a home in Morgan Hill, Gilroy, or San Martin, you already know the two facts that govern most financial decisions around here: property values are high, and property tax rules are complicated. Santa Clara County property tax bills already run about three times the national median. When you layer on Prop 13, Prop 19, the 2024 NAR commission settlement, and Bay Area construction costs, even a small decision (build the ADU, wait to sell, inherit the house) can move six figures in either direction.
We built four free calculators specifically for the South Valley. No signups, no paywall, no generic state-wide assumptions that get the local rates wrong. Each one runs in about 60 seconds and gives you a real dollar number tailored to Morgan Hill, Gilroy, or San Martin. Here's when to use each.
1. Home Value Estimator
When to use it: You want to know what your home is worth right now, without talking to an agent yet.
Most online home value tools (Zillow, Redfin, Chase) run state-wide or nation-wide pricing models. Ours uses recent local 90-day comps for each zip (95037, 95020, 95046) and adjusts for your bed/bath count, year built, lot size, and condition. The per-square-foot baselines are calibrated monthly from actual Morgan Hill, Gilroy, and San Martin sales.
Try it: Home Value Estimator
We also surface recent comparable sales on request. If you pick "planning to list" or "within 3 months" as your timeline, our partner agent in your zip will send a free one-page pricing memo with your block's last 5 sales.
2. Property Tax and Prop 19 Calculator
When to use it: You're buying, inheriting a home from a parent, or over 55 and moving.
This is the tool most Morgan Hill and Gilroy homeowners actually need but can't find anywhere else. It runs three scenarios from one form:
Buying a home: Year 1 property tax plus the one-time supplemental bill (the surprise invoice most first-time buyers miss).
Inheriting from a parent: Prop 19 parent-child transfer math with the $1,044,586 cap that's in effect through Feb 15 2027. We show exactly how much of your parent's low Prop 13 base transfers with you.
Over 55 downsizing: How much of your existing Prop 13 base follows you to the replacement home, up to 3 times in a lifetime under Prop 19.
The county assessor publishes a generic calculator but it's designed for professionals. Ours speaks plain English and flags the three filing deadlines (12 months, 1 year, 3 years) that wreck families who miss them.
3. ADU Cost and Permit Estimator
When to use it: You're thinking about a backyard cottage, garage conversion, or junior ADU.
Bay Area ADU pricing is unusual. Construction runs $400-$650 per square foot, permits in Morgan Hill are $3,000-$10,000, and under state law AB 68, ADUs under 750 square feet pay zero impact fees. Miss that 750 threshold by even 10 square feet and you can add $5,000+ in school and city fees overnight.
Our calculator accounts for:
4 ADU types: detached, attached, garage conversion, junior ADU
Finish level (basic, mid, high-end)
Pre-approved plan vs custom architect-designed
City-specific permit fees for Morgan Hill, Gilroy, and San Martin
San Martin parcels get a septic/fire marshal adder
Estimated monthly rent and payback years
You also get a "Good to know" breakdown flagging things like the 750 sqft impact-fee threshold, whether your Prop 13 base stays intact (spoiler: only the new construction gets assessed), and which state law lets you stack a JADU plus attached plus detached on the same lot.
Try it: ADU Cost Calculator
4. Net Proceeds Calculator
When to use it: You're selling (or thinking about it) and want to know what you'll actually pocket.
This is the seller's mirror of the home value estimator. Plug in your expected sale price, mortgage balance, purchase history, and improvements, and the calculator walks through:
Agent commission (2.5% listing-side or the full 5-5.5% split)
California's $1.10 per $1,000 documentary transfer tax (Morgan Hill, Gilroy, and unincorporated SCC don't add city transfer tax on regular sales, so it's just the state levy)
Escrow, title, NHD report, and home warranty
Mortgage payoff
Section 121 capital gains exclusion ($250K single / $500K married filing jointly)
Federal 15% LTCG plus California 9.3% ordinary-income treatment on the taxable gain
Long-time Morgan Hill owners are the ones this tool was designed for. If you bought in the 1990s or early 2000s for $400K and sell for $1.8M, your gain can blow past the $500K exclusion and cost you $40-80K in capital gains tax. Most sellers don't see this coming until escrow.
Try it: Net Proceeds Calculator
How the tools work together
The tools are designed to compound. A typical South Valley homeowner journey looks like this:
Curious: run the Home Value Estimator to see what the house might fetch.
Planning: run the Net Proceeds Calculator to see what you'd actually keep after commission, transfer tax, and capital gains.
Building instead: run the ADU Cost Calculator to compare 'build an income unit' vs 'sell and move.'
Inheriting: run the Property Tax + Prop 19 Calculator to see whether keeping your parent's low tax base is worth making the home your primary residence.
All four tools are free, no-signup, and updated with local Morgan Hill, Gilroy, and San Martin data. If you submit the partner-lead form at the end of any tool, we connect you with a local SVS partner (agent, estate attorney, ADU builder, or CPA) who follows up within 24 to 48 hours. No pitch, no spam.
Why we built these
We started South Valley Spotlight because the local information ecosystem is fragmented. Morgan Hill Times covers city hall, Gilroy Dispatch covers Gilroy, Visit Morgan Hill covers wineries, and the county assessor publishes technical documents nobody reads. Nothing in between helps a regular homeowner decide 'should I sell, remodel, build an ADU, or just sit tight?'
These calculators are our attempt to close that gap with tools that:
Run on local data, not national averages
Explain the math instead of hiding it
Flag the deadlines that matter (the three Prop 19 filing windows, the 2-year Prop 19 replacement window, the 5-year Section 121 residency window)
Connect you with a local pro when you want more than a calculator
Bookmark whichever one matches your situation. Come back when your situation changes. And if you think we should build a fifth, reply to this post or email us at [email protected].
Sheena and Ryan cover Morgan Hill, Gilroy, and San Martin in a free weekly newsletter. Subscribe here.