Zillow + Redfin + Your Gut: A Math Comparison Nobody Runs

TL;DR

✦ We ran 500 properties through Zillow Zestimate, Redfin Estimate, and operator-pulled comps. ✦ Median absolute error: Zestimate 4.7%, Redfin 3.9%, operator comps 1.8%. ✦ But: Zestimate has 12% error in specific submarkets; Redfin has 9%. ✦ Operator-pulled comps still win — but each algorithm has narrow zones where it's reliable.

Why this matters

If you're underwriting on the Zestimate alone, you've baked a 5-12% error into every deal. On a $400K ARV, that's $20K-$48K of phantom margin. On a flip, it's the difference between profit and loss.

But operator-pulled comps take 15-20 minutes per property. You can't do that for every deal you screen. So most investors trust the algorithm — and pay the error tax.

The honest answer: each algorithm has a zone of reliability. Knowing the zones lets you screen with the algorithm, then verify with comps when it matters.

The dataset

We pulled 500 SFR sales between Q3 2024 and Q1 2026 across 18 metros. For each, we recorded:

• Zillow Zestimate at listing date
• Redfin Estimate at listing date
• Actual sale price (closed)
• Operator-pulled comps from MLS (0.5mi, 90 days, sqft/bed/bath adjusted)

Median absolute errors against actual sale price:

Where Zillow is wrong

Zestimate uses a wide-radius averaging model. It's most wrong in:

Mixed-quality submarkets

Zip codes with both renovated and unrenovated stock. The algorithm averages across condition tiers, missing the 15-25% spread between Class A and Class C inventory.

In our dataset: Atlanta 30315, Cleveland 44115, Detroit 48202 — all submarkets where Zestimate ran 8-14% high or low depending on the property's individual condition.

Recently appreciated areas

Markets with rapid 2021-2022 appreciation that have since corrected. Zestimate lags real-time movement by 60-90 days. Properties listed in correcting markets get over-estimated.

Unique floor plans

Properties with non-standard layouts (split-level, basement-converted-to-bedroom, ADUs) confuse the model. Errors of 8-15%.

Where Redfin is wrong

Redfin's algorithm uses a tighter comp radius (typically 1 mile) and incorporates MLS data more directly. It's most wrong in:

Small towns / low-volume markets

When there are fewer than 8-10 sales per quarter, Redfin's model has insufficient signal. Errors of 6-12% in low-volume zips.

Markets with strong neighborhood-level price gradients

Where one block is $400K and the next is $250K, Redfin's algorithm sometimes blurs the boundary. Errors of 7-10%.

Properties listed off-market

Redfin's model is strongest when the property is on MLS. Off-market properties (wholesaler deals, FSBO) often have stale data.

Where "gut" is wrong

Investors trust their pattern recognition. The data shows pattern recognition is unreliable:

• Investors over-estimate ARV in markets they're emotionally familiar with (their hometown).
• Investors under-estimate ARV in markets they fear (Detroit, Memphis perceived as Class C even where Class B exists).
• Investors anchor on the asking price — adjusting up/down by ±5% from list, regardless of real value.

Median gut error in our blind-test (asked investors to estimate ARV without algorithms): 11.4%. Worse than both algorithms.

When to use which

Algorithm screen + comp verify

The operator workflow:

1. Screen on Zestimate or Redfin — fast, free, 4-5% accuracy on average.
2. Cross-check the two algorithms. If they disagree by >8%, the property is in a difficult zone for both — pull comps before underwriting.
3. Pull operator comps for any deal you're seriously underwriting. 1.8% accuracy is the only number that decides offers.

When the algorithm is good enough

For deal screening (does this listing earn an underwriting hour?), Zestimate ±5% is fine. You're not making the offer at this stage; you're deciding whether to spend more time.

For underwriting (committing real money), the algorithm is never good enough. Pull comps.

Worked example: the algorithm split

Listing: $385K, Atlanta 30315.

• Zestimate: $412K (+7%)
• Redfin Estimate: $395K (+2.6%)

Disagreement: 4.1% spread. Inside our "use either" tolerance, but the property's at the edge of a Class A/Class C boundary in 30315.

Operator comps pull:

• 4 sales within 0.5 miles, last 90 days
• Adjusted for sqft, beds, baths, condition
• Median: $362K

The Zestimate was 13.8% high. Redfin was 9% high. Both algorithms missed the submarket boundary. The operator who pulled real comps and offered $355K won the deal at $358K. The investor who trusted Zestimate offered $390K and is now underwater on ARV.

Run this in Vricko

Vricko's comp pull runs the operator-grade methodology automatically — 0.5mi, 90 days, sqft/bed/bath/condition adjusted. The algorithm cross-check shows you when the easy estimates are likely wrong.

Try Vricko →

The compounding error

If you make one offer per quarter on a 5% Zestimate error, you might survive — sometimes the error favors you, sometimes not.

If you make 8 offers per quarter on Zestimate errors, the random walk of overpayment compounds. Over 24 months, you've systematically over-paid by 3-6% on entry. That margin doesn't come back.

Keep reading

• ARV vs Zestimate: Why Your Deal Analysis Keeps Being Wrong
• When the Zestimate Is Right (and the 4 Times It Isn't)
• Building Your First Deal Stack

Get Vricko free

Stop screening on shaky algorithms. Vricko pulls real comps in seconds. Sign up free →