Product info
California eSIM plans
| Unlimited data · 5 days | $17.99 | Buy eSIM |
| Ohayu recommendsUnlimited data · 10 days | $33.99 | Buy eSIM |
| Unlimited data · 15 days | $39.99 | Buy eSIM |
| 3GB prepaid eSIM · 14 days | $8.49$2.83 / GB | Buy eSIM |
| 5GB prepaid eSIM · 30 days | $13.49$2.70 / GB | Buy eSIM |
| 10GB prepaid eSIM · 30 days | $21.49$2.15 / GB | Buy eSIM |
| 15GB prepaid eSIM · 60 days | $27.79$1.85 / GB | Buy eSIM |
| 20GB prepaid eSIM · 90 days | $34.49$1.72 / GB | Buy eSIM |
| 50GB prepaid eSIM · 90 days | $73.49$1.47 / GB | Buy eSIM |
You can install your eSIM before the trip and activate it when you arrive in United States. Validity starts after eSIM activation.
Plan details
How much mobile data you need
What's the best eSIM for California?
One city, few days – 3 GB
Maps and rideshare.
A week driving – 10 GB
Sustained navigation between cities.
The full coast run – 20 GB
San Diego to San Francisco, plus the parks.
Longer stay – Unlimited
Tethering from a city base.
Coverage and network
Coverage across a very large state
United States mobile networks
California is roughly the length of Britain and Italy combined, and coverage varies accordingly. The cities and the interstate corridors are strong. The two things that catch drivers out are Big Sur and the mountain parks, both of which are genuinely offline in places. (Speedtest by Ookla, June 2026)
Speedtest Global Index · Mobile · United States · June 2026
Download
197.34 Mbps
Upload
10.35 Mbps
Latency
27 ms
Global rank
#10 of 98
What varies where
- LA, the Bay Area, San Diego: Dense 5G across all three metros, including the transit systems.
- Highway 1 through Big Sur: The famous stretch is also the famous dead zone. Expect an hour or more with nothing between Carmel and San Simeon, and no reception at several of the viewpoints.
- Yosemite, Sequoia, the Sierra: There is signal at some entrances, visitor centres and lodges. On the valley floor it is unreliable and on the trails it is absent.
- I-5 and the Central Valley: The interstate itself is well covered end to end. Smaller agricultural roads off it are patchier than the map suggests.
From San Diego to the Oregon line
The same plan works in every state, so crossing into Nevada for Vegas or Arizona for the canyon changes nothing.
How to install eSIM
Connected in 3 steps
- 01
Buy before you fly
Choose your data plan before your trip.
- 02
Download & install
Log in to your account, tap your eSIM, and follow the on-screen instructions.
- 03
Land & activate
Activate when you arrive in United States. Turn on roaming for the eSIM and it connects to a local network.
Before you buy, make sure your phone supports eSIM — see Ohayu compatible devices list or dial *#06#. It's a free request to your phone's settings. If you see the EID number — your phone is eSIM-compatible.
Arriving in California
Airport Wi-Fi in California
LAX, SFO and San Diego all offer free terminal Wi-Fi with no session cap.
Side by side
California eSIM Comparison
Indicative comparison based on publicly listed USA plans as of July 2026. Competitor pricing and policies change - check their sites for current terms.
Frequently asked questions
Where to buy a SIM card in California?
All three major airports have carrier kiosks, priced well above retail. Target, Walmart and Best Buy in any city are cheaper. An eSIM removes the stop.
Is ID needed for prepaid across California?
No. Prepaid lines are not registered to individuals in the US, so nothing is recorded against your name. Buying an eSIM online involves no verification either.
Will it work in Yosemite and on Highway 1 through Big Sur?
Not consistently, and you should plan for that. Big Sur has long unserved stretches between Carmel and San Simeon. Yosemite has patchy signal at entrances and lodges, little in the valley and none on the trails. Download offline maps and any reservations before you leave the coast highway or enter a park.
eSIM not working in California?
If you are in Big Sur or inside a national park, there is probably no mast in range - that affects all carriers. In a city, check the Ohayu eSIM is your data line, roaming is on for it, then cycle Airplane mode. Chat and support@ohayu.com are open 24/7.
