Castro Valley vs. Union City vs. Newark: Where to Rent in the East Bay in 2026
Most East Bay rental searches start with Oakland, Berkeley, Fremont, or Hayward. Castro Valley, Union City, and Newark sit in the gaps between those names, and renters tend to scroll right past them. That is a mistake if your budget is between $2,200 and $2,900 and you need either a BART seat or a reasonable drive to the Peninsula.
These three are not interchangeable. One is unincorporated county land in the hills with a BART station. One is the best-positioned transit city in the southern East Bay. One has almost no transit at all but puts you minutes from the Dumbarton Bridge. Here is how they compare in 2026.
Why these three belong in the same search
Draw a line down I-880 from San Leandro to the Dumbarton Bridge. Castro Valley sits just east of that line where I-580 and I-238 meet. Union City sits on it, halfway between Hayward and Fremont. Newark sits west of it, wrapped by Fremont on three sides and by the bay and the Cargill salt ponds on the fourth.
What they share is a price position. Fremont averages roughly $2,900 to $2,950 across all unit types in 2026, with one-bedrooms near $2,600 and two-bedrooms above $3,200. Hayward averages closer to $2,450 to $2,500, with one-bedrooms around $2,230. All three of our cities land in between, and each one gives you something Fremont and Hayward do not.
What they do not share is housing stock. Castro Valley is mostly single-family homes and small complexes, so apartment inventory is thin and turns over slowly. Union City has real mid-rise and garden-apartment inventory plus a growing cluster of new construction near BART. Newark has the newest buildings of the three, because the city has been approving large residential projects on former industrial and bayfront land for years.
What you will actually pay in 2026
Treat all of these as ranges, not quotes. Small-market rent data swings hard month to month because a handful of listings can move the average, and you will see individual sources disagree by $300 or more on the same city.
Castro Valley
Overall averages cluster around $2,500 to $2,625. By unit type, expect studios roughly $1,200 to $1,700, one-bedrooms around $1,950 to $2,300, two-bedrooms around $2,400 to $2,700, and three-bedrooms starting near $3,100. Castro Valley is one of the few Bay Area submarkets where year-over-year rent has been flat or slightly down, with some sources showing a drop of several percent.
The catch is supply. A lot of what rents in Castro Valley is a house, a duplex half, or an in-law unit listed by an individual owner rather than a leasing office. That means fewer listings, less predictable pricing, and far more competition for the good ones.
Union City
Overall averages sit near $2,495 to $2,550. One-bedrooms are the noisiest number in the whole comparison, with credible sources landing anywhere from $2,200 to $2,700, so budget around $2,400 to $2,500 and treat anything under $2,300 as worth seeing quickly. Two-bedrooms generally run $2,600 to $3,000.
Newark
Newark is the most expensive of the three, averaging roughly $2,700 to $2,850. Two-bedrooms sit around $2,700 to $2,900, and one-bedrooms around $2,300 to $2,600. You pay that premium for newer buildings and for Dumbarton access. Single-family rentals in Newark frequently list at $4,000 and up, so if you see a median near that figure, it is counting houses, not apartments.
Castro Valley: hillside quiet with a BART station
Castro Valley is the largest unincorporated community in Alameda County. There is no mayor and no city police department, so the county sheriff and county fire handle services. For a renter this mostly shows up in slower code enforcement and in the fact that Castro Valley has no local rent control ordinance of its own, which puts you under California's statewide rules rather than something stricter like Oakland's or Hayward's.
The layout is simple. Castro Valley Boulevard is the commercial spine, running east from the BART station past the main retail strip. Redwood Road climbs north toward Lake Chabot Regional Park, which gives you more than 20 miles of trails and a marina roughly 10 minutes from most of town. Head east and you reach Five Canyons and Palomares Hills, two hillside master-planned neighborhoods built mostly from the 1980s through the early 2000s. Both are overwhelmingly owner-occupied, so rentals there are usually whole houses or townhomes.
The BART station is the real draw, and it is underrated. Castro Valley is on the Dublin and Pleasanton line, which runs direct into downtown San Francisco without a transfer. Figure roughly 40 minutes to Embarcadero. That is competitive with a lot of Oakland neighborhoods, for several hundred dollars less in rent.
Castro Valley Unified School District has a strong local reputation, which matters if you are renting with kids and also means family-sized rentals get the most competition.
Rent here if you want trail access and a quiet street, you commute to San Francisco or the Tri-Valley, and you are willing to wait for the right listing instead of choosing from twenty at once.
Union City: the best transit position of the three
Union City was created in 1959 when the separate communities of Alvarado and Decoto merged, and you can still feel both. Decoto, west of the BART station, is the older grid of tree-lined streets with homes largely from the 1960s through the 1980s. Alvarado, to the north, mixes historic Old Alvarado with newer townhome pockets like Sugar Mill Landing and sits close to Union Landing, the big open-air retail center off I-880.
The reason to pick Union City is the station. Union City BART puts you on the Fremont line with a direct ride into San Francisco in roughly 45 to 50 minutes. More importantly, it is the eastern anchor of the Dumbarton Express, the DB and DB1 bus lines that run weekdays across the Dumbarton Bridge to East Palo Alto, Menlo Park, downtown Palo Alto, the Palo Alto Caltrain station, and Stanford Research Park. Almost nowhere else in the East Bay lets you reach both downtown San Francisco and Stanford on transit from one address. Union City Transit runs local routes 1 through 9 feeding the station, and AC Transit adds regional service.
The city has been building out a Station District around that transit hub, with hundreds of new apartments, condos, and townhomes approved on the land south of Decoto Road, including a meaningful share of below-market-rate units. Practically, that means more new inventory coming online near BART, and it means construction noise in parts of the station area right now. Ask about it on tours.
Union City schools are New Haven Unified, anchored by James Logan High School. Quarry Lakes Regional Recreation Area, shared with Fremont, gives you swimming and fishing on the east side of town.
Rent here if transit is non-negotiable, especially if you or a partner commutes to the Peninsula while the other goes into San Francisco.
Newark: the Peninsula commute play
Newark has no BART station. The nearest ones are Fremont and Union City, both a 10 to 15 minute drive depending on traffic. If you are a car-free renter, Newark is the wrong choice, and no amount of rent savings fixes that.
If you drive, Newark's geography is excellent. Highway 84 runs straight from town onto the Dumbarton Bridge, which means Menlo Park, Palo Alto, and the Stanford Research Park are genuinely close in off-peak traffic and tolerable at peak compared to going around the bay. Meta, Tesla, Logitech, and a cluster of life-science and hardware employers have Newark-area facilities, so plenty of people here have a sub-15-minute commute.
Old Town Newark along Thornton Avenue and Cherry Street is the historic core, with older housing and small infill projects. NewPark Mall anchors the retail center near the I-880 and Mowry interchange. The newest apartment inventory is generally in the planned communities on the western and bayfront side of the city, which is also where you will find the best amenity packages and the highest rents.
Two local realities worth knowing. Newark sits low and close to the bay, so check the flood zone designation and ask whether renters insurance needs a flood rider. And because the city is surrounded by Fremont, your address can say Newark while the park, grocery store, or school boundary you care about sits across a line you cannot see. Verify school assignment with Newark Unified directly rather than trusting a listing's claim.
Rent here if you drive, you work on the Peninsula or in Newark and Fremont itself, and you want a newer unit for less than Fremont charges.
How to choose between them
If you commute to San Francisco and want the shortest train ride, Castro Valley wins on time and Union City wins on frequency and backup options.
If you commute to the Peninsula, Newark wins if you drive and Union City wins if you do not.
If you want the lowest realistic rent, Castro Valley and Union City are roughly tied near $2,500 overall, with Castro Valley cheaper on one-bedrooms and Union City cheaper on larger units more often.
If you want a new building with a gym, parking, and in-unit laundry, Newark has the deepest supply, followed by the Union City station area. If you want a house with a yard, Castro Valley has the most of them.
What to know before you sign
None of these three cities has its own local rent control ordinance the way Oakland and Hayward do, so most tenants here fall under California's statewide protections for buildings older than 15 years. Confirm the building's age and ask directly whether the unit is covered, because that determines how much your rent can rise at renewal.
Budget for parking separately in Newark and the Union City station area, where newer buildings often charge for a space. In Castro Valley, where many rentals are houses, parking is usually included but utilities usually are not.
Finally, watch timing. All three markets are thin enough that inventory arrives in bursts. In Castro Valley especially, the right listing may appear once a month, so being set up to see it the day it posts matters more than negotiating hard on a listing that has sat for three weeks.
Iris tracks listings across all three of these cities as they post, so you can describe what you need in plain language and get matched to units that fit instead of refreshing three different search sites. If you are comparing the East Bay's middle, that is the fastest way to see everything that is actually available right now.