DB LabsThe Idea
Choosing iPhone storage by gut feel usually leads to either buying too small and regretting it or buying too big and wasting money. A simple spreadsheet that calculates your typical photo, video, app, and message data needs gives you a clear answer. The basic formula: (monthly photos x average photo size) + (monthly video minutes x video size per minute) + apps + system + buffer. Multiply by 24 months for a 2-year plan. The result tells you which iPhone storage tier fits your life.
Why a Spreadsheet Beats Guessing
Apple sells iPhones in storage tiers that double in price every step up. The difference between 128 GB and 1 TB can be $400. That is real money to spend on something you may or may not need.
Most people choose by feel: I had 128 GB before and ran out, so I will go up to 256 GB. But this ignores how your usage actually grows over time and what specific things will fill the storage.
The Spreadsheet Columns
Build a simple spreadsheet with these rows. Use Apple Numbers, Google Sheets, or Excel. Or just write it down on paper.
Row 1: Operating System
iOS plus pre-installed apps uses about 18 GB on a fresh install in 2026. Subtract this from your nominal storage to get usable space. A 128 GB iPhone has about 110 GB usable.
Row 2: Photos
Estimate photos per day. Multiply by 30 for monthly. Multiply by 0.003 for GB per month (HEIC photos average 3 MB).
Example: 20 photos a day x 30 days x 0.003 GB = 1.8 GB per month. Over 2 years: 43 GB.
Row 3: Videos
Estimate video minutes per month. Multiply by GB per minute based on quality:
- 1080p 30 fps: 0.06 GB/min
- 1080p 60 fps: 0.09 GB/min
- 4K 30 fps: 0.27 GB/min
- 4K 60 fps: 0.40 GB/min
Example: 30 minutes per month at 4K 60 = 12 GB per month. Over 2 years: 288 GB. (This is why video planning matters.)
Row 4: Apps
Count the apps you actually use and add 30-50 percent buffer for apps you will install later. Average app size in 2026 is 200 MB. Heavy apps like games can be 4-8 GB each.
Example: 80 apps at 250 MB average = 20 GB.
Row 5: Messages
iMessage attachments grow over time. Budget 5-15 GB for 2 years of messages.
Row 6: System Data
Caches, indexes, and other system stuff. Budget 10-15 GB. This is hard to control.
Row 7: Buffer
Always leave 10-20 percent free for iOS to function smoothly. Below 5 GB free, performance degrades.
Sample Calculation: Light User
| iOS | 18 GB |
| Photos (10/day, 2 years) | 22 GB |
| Videos (10 min/month 1080p) | 22 GB |
| Apps (40 apps) | 10 GB |
| Messages | 5 GB |
| System Data | 12 GB |
| Buffer (15%) | 15 GB |
| Total | 104 GB |
A 128 GB iPhone is sufficient.
Sample Calculation: Heavy User
| iOS | 18 GB |
| Photos (50/day, 2 years) | 110 GB |
| Videos (60 min/month 4K 60) | 576 GB |
| Apps (100 apps) | 30 GB |
| Messages | 15 GB |
| System Data | 15 GB |
| Buffer | 100 GB |
| Total | 864 GB |
This person needs a 1 TB iPhone or must rely heavily on iCloud Photos with Optimize Storage.
The Optimize Storage Modifier
If you use iCloud Photos with Optimize iPhone Storage enabled, your photo and video totals shrink dramatically because originals live in iCloud. In the sample above, the heavy user could drop to 256 GB or 512 GB by using Optimize Storage and accepting brief download delays for old photos.
The Bottom Line
Spending 15 minutes on a storage plan saves hundreds of dollars over the life of your iPhone. The math is simple, the inputs are easy to estimate, and the answer is unambiguous.