Why It Matters
When a headline says "U.S. rents rose 3.2% year-over-year," that number almost always comes from ZORI. Zillow ingests the asking rents on every active listing in its network, filters to the 35th–65th percentile to strip out luxury and distressed outliers, and publishes a dollar-denominated monthly index at ZIP, metro, state, and national grain. For investors, ZORI answers "which markets have rent momentum right now?" and "where are asking rents slowing down?" The catch — and it's a real one — is that ZORI is asking rent, not executed rent. Landlords who renew an existing tenant at 2% don't show up in ZORI; only the new listing at the higher ask does. That asking-vs-executed gap is why metros can look hot on ZORI and flat on what landlords actually collect. Pair ZORI with HUD Fair Market Rent (metro level, different grain) and your local property-management data for a complete read.
At a Glance
- What it is: Monthly dollar-denominated index of asking rents at ZIP, metro, state, and national grain.
- Who publishes it: Zillow Research. Free data downloads at research.zillow.com/data.
- What it measures: The smoothed mean of asking rents in the 35th–65th percentile range on active listings. Asking rents only, not executed rents or renewal rents.
- Coverage: ~850 metros, ~30,000 ZIPs, all 50 states + DC. Published separately for single-family vs multifamily.
- Publication lag: ~2 weeks after month-end. March series typically publishes mid-April.
- Methodology: Repeat-listing sampling, smoothed 3-month moving average, seasonally adjusted. Revised periodically as new data lands.
How It Works
Where ZORI comes from. Zillow operates the largest rental listing network in the U.S. When a landlord lists a unit on Zillow, Trulia, or HotPads, the asking rent gets captured. Zillow takes every active listing across its network, filters to the 35th–65th percentile of asking rents in each geography (stripping out luxury penthouses and rock-bottom distressed rentals), computes the mean, and smooths the result with a 3-month moving average. Then seasonal adjustment strips out the predictable May-to-September rent bump. What comes out is a monthly dollar number per ZIP, per metro, per state, per structure type. Unlike Home Price Index which is a unitless index, ZORI reports in actual dollars — the April 2026 ZORI for the Austin metro might be $2,180/month. That's the mean asking rent in the middle 30% of listings, not the median rent of occupied units.
ZORI vs FMR vs CPI-Rent — three different numbers, three different purposes. Investors confuse these constantly. HUD Fair Market Rent is an administrative benchmark calculated annually at the 40th percentile of gross rents (rent plus tenant-paid utilities) for standard-quality units across the whole metro — its purpose is setting Section 8 voucher caps. BLS CPI-Rent is a component of the Consumer Price Index that samples actual rents paid by a consumer panel, including renewing tenants — it's what the Fed watches for inflation, and it runs ~12 months behind ZORI because renewal rents reset slowly. ZORI is neither of those: it's the asking rent on new listings, today. When a new tenant signs a lease at the current ask, ZORI captures it. When an existing tenant renews at last year's rent, ZORI doesn't see it. That's why ZORI typically runs higher and moves faster than CPI-Rent.
What ZORI tells you as an investor. Three practical uses. First, cross-market comparison: if you're deciding between acquiring in Phoenix vs Memphis, pull 5 years of metro ZORI trends and compare the slope. Second, within-metro differentiation: ZIP-level ZORI shows which neighborhoods are pulling ahead. The Tempe ZIP near ASU might show ZORI up 4% YoY while a suburban Gilbert ZIP shows flat — different micro-markets, same metro. Third, early-warning signal: when ZORI decelerates or turns negative, new lease pricing has softened even if existing tenants are still paying last year's rent. That lag can be 6-12 months, so ZORI tells you what your cap rate will look like next year, not this year.
The coverage caveat. ZORI publishes for ~850 metros and ~30,000 ZIPs, but rural areas and smaller ZIPs with low listing volume get dropped or get wide confidence intervals. If you invest in a rural county or a ZIP outside a major metro, ZORI may not cover it — you'll see no data or a visibly noisy series. For those markets, fall back to HUD Fair Market Rent (covers every county) or local property-management data. ZORI is broad but not universal.
Real-World Example
Sofía Torres compares rent momentum in Raleigh vs Columbus before buying.
Sofía is a single-family rental investor deciding between two acquisitions: a 3-bed in Raleigh NC and a 3-bed in Columbus OH. The two properties have similar price points and similar current rent rolls. She wants to know which metro has stronger rent growth heading into the next 12-24 months.
She pulls ZORI for both metros from Zillow Research:
- Raleigh-Cary MSA ZORI (March 2026): $1,840/month, up 2.1% YoY (down from 4.7% YoY a year ago)
- Columbus OH MSA ZORI (March 2026): $1,420/month, up 3.4% YoY (up from 2.9% YoY a year ago)
The story in the numbers: Raleigh's rent growth is decelerating (from 4.7% to 2.1%). Columbus is accelerating (from 2.9% to 3.4%). Even though Raleigh still has the higher absolute rent, the momentum is moving toward Columbus.
She digs into ZIP-level ZORI within each metro. In Raleigh, the downtown ZIPs are decelerating hardest (new multifamily deliveries pressuring rents). In Columbus, the suburban ZIPs near the Intel fab site are accelerating fastest. That tells her WHERE inside each metro the rent story is playing out.
She cross-references with CPI-Rent (BLS) and HUD FMR to sanity check. CPI-Rent for the two metro regions tells a similar story but 12 months behind — Columbus CPI-Rent is still showing 2.4% where ZORI is 3.4%, which is consistent with the "asking rents accelerating, renewal rents catching up" pattern. HUD FMR (annual) confirms Columbus is still a below-median cost market with room for rent growth.
Her decision: Columbus. ZORI gave her a 20-minute read that would have taken hours of MLS and property-management data to replicate.
Pros & Cons
- Broadest free rental data source available — ~850 metros, ~30,000 ZIPs at monthly cadence
- Dollar-denominated (not just index level) — easy to compare across geographies
- 2-week publication lag is fast compared to HUD FMR (annual) or CPI-Rent (monthly but slow-moving)
- ZIP-level granularity reveals within-metro momentum differences
- Published separately for single-family vs multifamily — different markets, different trends
- Free, methodology is public and documented
- Asking rents, not executed rents — can overstate landlord cash flow growth
- Doesn't capture renewal pricing — existing tenants rolling over at last year's rent are invisible
- Coverage drops in rural areas and low-listing-volume ZIPs — no data for smaller markets
- Methodology revisions periodically reshape historical series — 2024 switched from repeat-rent to weighted mean
- Commercial source — the raw underlying data isn't publicly auditable the way federal data is
- Missing off-market SFR — landlords who fill vacancies through word-of-mouth never hit Zillow
Watch Out
- Asking ≠ executed: ZORI up 4% doesn't mean every landlord got a 4% increase. It means new listings are asking 4% more. Tenants on renewals may pay 0-2% increases. The gap widens in softening markets.
- Revisions can move history: Zillow revises ZORI as new data lands. The March 2025 reading you saw last year might read differently today. Pull fresh data for backtests, don't rely on archived snapshots.
- Low-volume ZIPs are noisy: A ZIP with 20 listings/month will have wide swings that don't reflect real rent movement. Check the listing count when reading ZORI at ZIP level — if it's under ~50, treat the number as directional only.
- Methodology changes: The 2024 switch from repeat-rent to weighted-mean methodology means pre-2024 ZORI is not directly comparable to post-2024 in the sense of the old methodology. Zillow backfilled the new series to 2015, but anyone citing "ZORI showed X in 2019" should verify which methodology they're quoting.
- Not every metro is covered: If you're investing outside a major metro, ZORI may have no data or missing ZIPs. Don't assume coverage — check the data file first.
Ask an Investor
The Takeaway
ZORI is the fastest, broadest free measure of asking-rent momentum in the U.S. For cross-market screening, within-metro ZIP analysis, and early-warning signals on rent deceleration, it's the default data source every institutional investor and housing analyst uses. The asking-vs-executed gap is real, so pair it with HUD FMR for the metro benchmark and local property-management data for what you'll actually collect. Pull ZORI at metro and ZIP level for your target markets, look at YoY and 2-year CAGR, check acceleration or deceleration, and treat it as the leading indicator it is. Free data at research.zillow.com/data, updated monthly, 2-week lag. Sister index ZHVI covers home values with the same methodology family.