Some buyers choose a 256GB used iPhone 15 Pro simply to “keep it longer”. That may be sensible for frequent video work, but first separate ordinary video from ProRes. Apple limits internal ProRes recording differently by capacity; this is a functional distinction, not only room for more files.
1. Find out what fills your current phone
Open Settings > General > iPhone Storage to see which apps and media consume the space. If you sync photos, also understand which versions remain locally and whether downloading originals requires a connection. iCloud capacity is not extra built-in phone storage.
Estimate how many videos you shoot each month, how often you offload them and which large apps must stay available offline. 128GB can fit lighter needs; 256GB reduces file housekeeping when active video projects live on the phone.
2. ProRes changes the 128GB decision
Apple says ProRes files can be much larger than HEVC. Its support table limits internal recording on 128GB models to 1080p 30fps, while 256GB and larger models can record ProRes 4K 30fps internally. This does not limit every video mode: ordinary 4K recording is a separate question.
If you mostly make family clips or short social posts in standard formats, you may rarely use ProRes. Do not pay more merely because a codec sounds professional. If you colour-grade video regularly, map out your editing and offloading workflow.
3. What does an external drive solve?
Apple supports recording ProRes directly to an external USB-C drive on iPhone 15 Pro, including 4K 60fps when the drive, format and cable meet its requirements. That enables a specific production workflow, but adds gear to carry, connect and manage.
Do not choose 128GB based only on “you can attach a drive” without checking speed, exFAT formatting, power and a USB 3 cable. A recording drive is not your backup; make another copy after the shoot.
4. More storage cannot repair a poor used unit
Compare Battery Health, Parts and Service History, Activation Lock, cameras, USB-C and appearance across the actual phones. A suspiciously cheap 256GB unit needs an explanation, not an automatic bargain label. Read the returns policy for that specific used item.
Verify the real capacity under Settings > General > About instead of a promotional picture. Try recording video and transferring a file through USB-C, checking for errors or abnormal heat.
5. Choose by workflow and today’s actual price gap
Choose 128GB when your current storage remains comfortable, you rarely keep large videos and you do not need internal ProRes 4K. Choose 256GB if you often shoot, edit and retain video on the phone or want internal ProRes 4K 30fps as listed by Apple.
TECHBUY’s used iPhone 15 Pro page shows current prices, colours, SIM options and capacities. Compare units in similar condition. Our eSIM versus physical SIM guide addresses regional versions before you order.
Conclusion
If you use internal ProRes, 128GB and 256GB differ in recording capability as well as capacity. For ordinary use, the actual phone’s condition and your file-management habits still matter most. Sources: Apple’s ProRes guide and storage check.
