Which capacity should you choose?
Apple lists 256GB, 512GB, 1TB and 2TB options in its technical specifications. There is no single best capacity without knowing what you store. Our approach is to estimate the space you want available near the end of ownership, then choose a tier with room above that estimate.
| Capacity | A reason to consider it | A reason to move up |
|---|---|---|
| 256GB | Your measured usage is modest, growth is slow and you are comfortable managing downloads | Your existing phone is already close to this amount, or you need a large offline library |
| 512GB | Your budget needs more space than the entry tier, but stays comfortably below this tier | Several years of photos, large games or local projects push your estimate near the limit |
| 1TB | You can identify substantial local files you intend to keep | Your actual working library and planned growth already require more |
| 2TB | You have a specific large local archive or working set and can justify its cost | More capacity will not solve an inadequate backup process |
These are decision conditions, not claims about how many photos or hours every phone can hold. File sizes vary with format, quality and app behavior. Advertised capacity is not all available for your own files; system software and installed apps also occupy space.
Make a five-line storage budget
Check the storage screen on your existing phone and record the date. Use actual usage, including apps and system space, rather than the capacity printed on its box.
- Starting usage: total space currently used, after removing only files you genuinely intend to leave behind.
- Growth: estimate annual net growth from your own history, multiplied by planned years of ownership. Do not count the same new photos in both growth and offline extras.
- Extra offline content: trips, downloaded courses, games or work projects beyond what the starting figure already includes.
- Working room: reserve space for updates, temporary files and editing/exporting projects. This is a chosen buffer, not a fixed Apple requirement.
- Estimated need: add the four amounts, then compare with the next suitable advertised tier and its available-space limits.
A worked example, with assumptions visible
Suppose your current usage is 110GB, you expect 25GB of net growth per year for four years, want 40GB of additional offline material, and choose a 50GB working buffer. The estimate is 110 + (25 × 4) + 40 + 50 = 300GB. Under those assumptions, 256GB is too small; 512GB is the first tier worth evaluating.
If the same person expects only 10GB of annual growth and needs no extra offline library, the estimate becomes 200GB. That changes the discussion, but still does not guarantee 256GB will suit future apps and system use. Replace every example number with your own. These are planning scenarios, not measurements from an iPhone Duo.
How much does each storage upgrade cost?
| Upgrade | USD | GBP | HKD | CNY |
|---|---|---|---|---|
| 256GB → 512GB | +200 | +200 | +1,800 | +2,000 |
| 512GB → 1TB | +400 | +400 | +3,500 | +3,500 |
| 1TB → 2TB | +600 | +600 | +5,200 | +5,000 |
The differences above use the same regional price data as our full price comparison, last price-checked September 13, 2026. They compare adjacent capacities in each store’s own currency, without exchange-rate conversions, trade-ins or financing. Follow the store links on the price page before ordering.
A useful personal check is to divide an upgrade’s extra cost by your expected ownership months. That spreads the device premium for comparison; it is not a financing offer or a prediction of resale value.
Can cloud storage replace a larger phone?
Cloud space and local device capacity solve different problems. Compare two realistic routines: keeping your library locally, or keeping some originals online and downloading them when needed. Include the ongoing subscription cost over your ownership period, not just its first month.
Then ask what happens with unreliable Wi-Fi, a limited mobile plan or a long trip. Check which files and apps must work offline. Avoid assuming every app can move all its data to a cloud service, or that a streaming subscription permits every title to be downloaded indefinitely.
For creative work, allow temporary space for both source files and exports. In Duo Studio, your chosen local media and an exported film may coexist while you work. Save the export somewhere intentional; additional phone capacity alone is not a backup.
Before ordering
Keep a copy of your worksheet, your current usage figure and the assumptions behind your growth estimate. If two tiers both cover it, the smaller one may be a reasonable budget choice. If your estimate barely fits, revisit the buffer and the cost of deleting or moving files later.
Continue with the buying checklist or the Hong Kong vs mainland China guide if network activation is also part of your decision.