Updated 2026-04-25 · honest, vendor-neutral comparison
Zestimate is Zillow's free AVM. It produces a single home-value number for ~90% of US residential addresses, with median absolute error around 7.5% on off-market homes (1.9% on active listings). It's the right choice when you need a quick free number for a starting-point check. Twellie is a paid report ($50/address). It uses a similar four-model AVM ensemble plus AI photo condition grading, then bundles the number with eight comparable sales (with line-item adjustments), a true cost-of-ownership model, a risk profile, and a negotiation strategy. Use Zestimate for casual browsing and the starting-point AVM. Use Twellie when you're about to write an offer and need to defend the price.
Both tools answer the question "what's this home worth?" — but they answer it at different depths and for different stages of the buying journey.
If you're casually checking your friend's house at a dinner party, Zestimate is the right tool. If you're 7 days from making a $400,000 offer, the math changes.
| Feature | Zestimate | Twellie |
|---|---|---|
| Coverage | ~104M US homes | ~155M US residential addresses |
| Pricing | Free | $50 per address; $199/mo for 6 reports |
| AVM accuracy (off-market) | ~7.5% MdAE | ~7% MdAE |
| AVM accuracy (active listings) | ~1.9% MdAE | Comparable when listing photos available |
| Confidence band shown | Yes (range) | Yes (range + per-model output) |
| Comparable sales shown | Recent sales nearby | 8 comps with line-item adjustments |
| Photo condition grading | No (off-market) | Yes (room-by-room AI grading) |
| True cost of ownership | Mortgage estimate only | Full: tax + insurance + maintenance + HOA |
| Risk profile (FEMA, climate) | Climate Risk only | FEMA flood + climate + environmental |
| Negotiation strategy | No | Yes (recommended offer + walk-away) |
| Inspection-response generator | No | Yes (AI-drafted credits / repairs) |
| Closing-day workspace | No | Yes (CD verifier, wire-fraud check) |
| Methodology disclosure | Black-box | Public, benchmarked vs Quantarium / HouseCanary |
| Agent-referral incentive | Yes (Zillow Premier Agent) | None |
| Best for | Quick free number, starting point | Active offer, deep due diligence |
Use Zestimate when:
Use Twellie when:
Honest acknowledgement. Zillow has 20 years of data and a massive distribution advantage. Twellie is newer, paid, and earns its fee by going deeper than a free single-number AVM can. We're not trying to replace Zestimate — we're replacing the buyer's agent, and Zestimate is a complement to that.
Try Twellie
Skip the average $25,270 buyer-agent commission and pocket the difference. $50 per report — yours forever.
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