The old rule of thumb — “monthly plans give you more data per dollar, prepaid is only for visitors” — is wrong in 2026. Once you price it out, prepaid often delivers more data for less money. The real trade-offs are speed, expiry and the extras you get bundled. Here is how the numbers actually look.
| Prepaid SIM | Monthly plan | |
|---|---|---|
| Example | SoSIM 60GB FUP + 5,000 mins | 3HK 5G 30GB SIM-only |
| Price | HK$48 / 30 days | HK$124 / month (24-mo) |
| Per GB | ≈ HK$0.80 | ≈ HK$4.13 |
| Speed | Capped (SoSIM 42Mbps) | Full 5G speeds |
| Commitment | None — renew when you want | 12–24 months |
Before you decide, you need to know how much data you actually use — that single number drives everything below. Most people overestimate it. Your phone already records it for free, so check your last few months first.
What prepaid actually costs in 2026
SoSIM (3HK network) is the price benchmark. A new card costs HK$33 and includes 50GB of local data (fair-use, then throttled to 128kbps) plus 1,500 voice minutes for the first 30 days. After that, renew at HK$48 for 30 days and it upgrades to 60GB with 5,000 minutes. That works out to roughly HK$0.80 per GB — far below almost any monthly plan.
If you want longer validity, Lucky SIM (China Mobile HK network) sells big data packs instead: 365-day 20GB + 2,000 mins for HK$100, 2-year 100GB + 3,000 mins for HK$225, and 3-year 200GB for HK$328. These suit light users who never want to think about renewing. Club SIM (csl network) is the opposite end — app-first and flexible, but its data packs run HK$38 for 1GB up to HK$168 for 10GB, so it is not the pick for heavy data.
What a monthly SIM-only plan actually costs
Monthly plans have fallen a lot, but they still cost more per GB than the best prepaid. Using current published SIM-only prices: CMHK 5G 40GB is HK$88/month (12-month), SmarTone 5G 50GB is HK$118/month (24-month), 3HK 5G 30GB is HK$124/month, and 3HK 5G 100GB is HK$228/month. Even the cheapest monthly sits at roughly HK$2–4 per GB.
The 30GB-a-month test
Take a person who really uses about 30GB a month, mostly on Wi-Fi at home and work. On prepaid, one SoSIM renewal covers them at HK$48 — the 60GB pack even leaves headroom. Over a year that is about HK$576. On a monthly plan they need the 30–40GB tier: CMHK 40GB at HK$88 works out to HK$1,056 a year, and the 3HK 30GB plan at HK$124 costs HK$1,488 over 12 months. Prepaid is roughly 40–60% cheaper for the same usage.
Prepaid gotchas worth knowing
- Data and number expire. A SoSIM card is valid 120 days after activation; you must top up at least HK$20 to keep the number alive (top-ups can extend validity up to 730 days).
- Registration is mandatory. Under the SRRS every prepaid SIM must be tied to an ID before use — you can register up to 10 prepaid cards per operator. See our real-name registration guide.
- Speed is capped. SoSIM runs up to 42Mbps (4.5G), so heavy downloaders or gamers may notice slower speeds than a 5G monthly plan.
- No bundled China or roaming data. If you cross the border weekly, a monthly plan with built-in GBA data usually beats stacking prepaid roaming add-ons.
- New prepaid numbers announce themselves. Outgoing calls from a freshly activated prepaid card play an OFCA-mandated “this call is from a new prepaid card” notice to the person you ring — small but real friction.
Choose prepaid if…
- You are visiting Hong Kong short-term.
- You use under ~20GB a month and want the cheapest data per GB.
- You want a spare or second line you control by topping up.
- You are giving a line to a kid, a senior or a domestic helper who only needs the basics.
Choose a monthly plan if…
- You want full 5G speeds for streaming, gaming or hotspot.
- You cross into Mainland China or the Greater Bay Area regularly and want bundled data.
- You value premium roaming day-passes, physical stores and real support.
- You prefer one fixed, predictable bill — even if it costs more per GB.
You can switch without losing your number
Number portability in Hong Kong is free, quick and works in both directions — you can move a prepaid number onto a monthly contract, or drop a monthly plan down to prepaid, and keep the same digits. SoSIM’s self-service port-in can complete in as fast as 3 days. If you are not sure, start cheap on prepaid, test the network, then port up. See our number-porting guide for the steps.
Frequently asked questions
Is prepaid actually cheaper than a monthly plan in Hong Kong?
For data, usually yes. SoSIM renews at HK$48 for 60GB (≈HK$0.80/GB) while a 30–40GB monthly plan costs HK$88–HK$124 a month. Prepaid is roughly 40–60% cheaper for a ~30GB user — but it caps speed at 42Mbps, expires if you stop topping up, and has no bundled China or roaming data.
Can I keep my number if I switch between prepaid and monthly?
Yes. Hong Kong number portability is free and works in both directions, so you can move a prepaid number onto a monthly plan or back again and keep your digits. See our number-porting guide for the steps.
Do prepaid SIMs expire in Hong Kong?
Yes. A SoSIM card, for example, is valid 120 days after activation, and the number is lost once it lapses unless you top up. Topping up at least HK$20 extends validity, and larger top-ups can push it out to 730 days.
How many prepaid SIMs can one person register?
Under the SRRS you can register up to 10 prepaid SIMs with each mobile operator. If you hit the limit with one operator, you can still register cards with another.