Why You Should Calculate, Not Just Compare Monthly Fees
A lower monthly fee does not automatically mean a lower total cost. A 36-month contract can look cheaper per month while costing more overall, because you pay for 12 extra service months. This guide shows the break-even method, then illustrates it with a clearly labelled hypothetical example and verified same-tier 3HK plans checked against GoPlan Production data on 2026-09-21.
Hong Kong Contract Terms: What the GoPlan Snapshot Shows
In GoPlan Production data checked on 2026-09-21, contract terms are not limited to two choices: 0 months (1 plan), 24 months (68 plans), 28 months (2 plans), 30 months (14 plans) and 36 months (55 plans). These are plan counts in the dataset, not market share or a popularity ranking. 24-month and 36-month terms are the mainstream options, but 30-month terms also exist.
Hypothetical Example: HK$128 x 24 Months vs HK$108 x 36 Months
This example is hypothetical and is not a quote from any real provider. It exists only to show the arithmetic. The 24-month option costs HK$128 per month; the 36-month option costs HK$108 per month. The monthly difference is HK$20, and the extra commitment is 12 months.
| Item | 24-month option | 36-month option | Difference / note |
|---|---|---|---|
| Monthly fee (hypothetical) | HK$128 | HK$108 | HK$20 lower per month |
| Contract term | 24 months | 36 months | 12 extra months |
| Total spend (hypothetical) | HK$3,072 | HK$3,888 | 36-month total is HK$816 higher |
| Like-for-like first 24 months | HK$3,072 | HK$2,592 | HK$480 saved at the lower rate |
| Cost of the extra 12 months | Not applicable | HK$1,296 | Cost of extra service months, not a net loss |
Break-Even Method: How Cheap Must 36 Months Be?
Break-even means finding the monthly fee at which the 36-month option no longer costs more than the 24-month option over the same 36-month horizon. The formula is: 24 x M24 + 12 x expected future monthly fee versus 36 x M36. In the hypothetical example, HK$3,072 + 12 x HK$68 = HK$3,888, so the future monthly fee break-even is HK$68. This is a scenario threshold, not a forecast of market prices.
- Compare total spend over the full contract term, not the headline monthly fee.
- Compare like-for-like spend over the first 24 months when both options cover the same service.
- Compare cost per GB only when the local data allowances are the same or genuinely comparable.
- Treat the extra 12 months as an option cost, not just a discount.
Opportunity Cost: What You Give Up by Locking In 12 More Months
Market prices may change within 12 months, and your data needs may rise or fall. A longer contract also reduces flexibility to switch provider, renew on new terms or port in elsewhere, and you may miss new-customer or renewal promotion windows. Opportunity cost cannot be reduced to one number; assess it against your own usage and plans.
Early Termination Risk: The Real Constraint of a 36-Month Contract
Early termination usually involves remaining contract charges, an administrative fee or a specified calculation method. The exact amounts and terms are not listed in the GoPlan snapshot, so they are not stated here. The longer the contract, the longer the remaining period and the longer the potential risk window. Confirm the written early termination terms before signing.
Verified Same-Tier Example: 3HK 5G 24-Month vs 36-Month
Each pair below is 3HK, 5G, open eligibility, unlimited after allowance, 1 Mbps post-FUP and the same Greater Bay Area allowance, with one line. In this snapshot, the 36-month member has the same monthly fee but 50% more local data. That is extra data rather than a lower monthly fee, and it should not be generalised to all providers.
| Monthly tier | 24-month plan | Local data | 36-month plan | Local data | Greater Bay Area data | Post-FUP speed | Term difference |
|---|---|---|---|---|---|---|---|
| HK$88 | 5G 手機計劃 30GB · 24 個月 | 30GB | 5G 手機計劃 45GB · 36 個月 | 45GB | 2GB | 1 Mbps | 12 extra months, 50% more local data |
| HK$118 | 5G 手機計劃 60GB · 24 個月 | 60GB | 5G 手機計劃 90GB · 36 個月 | 90GB | 4GB | 1 Mbps | 12 extra months, 50% more local data |
| HK$163 | 5G 手機計劃 120GB · 24 個月 | 120GB | 5G 手機計劃 180GB · 36 個月 | 180GB | 6GB | 1 Mbps | 12 extra months, 50% more local data |
Who Should Choose 24 Months, and Who Should Choose 36 Months?
Choose 24 months if your data needs may rise, you want to keep flexibility to switch or port in, you expect market prices or promotions to change, or you do not want long-contract early termination risk. Choose 36 months if your data needs are stable, the same monthly fee clearly buys you more local data, you are confident you will not need to switch within three years, and you accept a longer commitment. If you are unsure about usage or may relocate or switch, a no-contract option may suit you better.
Pre-Signing Checklist
- Calculate total spend over the full contract term, not just the monthly fee.
- Confirm contract term, monthly fee, local data, post-FUP speed, Greater Bay Area data and roaming data.
- Confirm the early termination terms and how any charge is calculated.
- Confirm whether the promotion applies for the whole contract term.
- Compare at least one same-tier 24-month and 36-month option.