This page is the citable version of our data: five reference tables, one URL, every figure labelled. Reference pages exist to be pointed at, so nothing here depends on the article around it — each table can be lifted on its own. Where a figure comes from an Apple support page, the link sits in the table. Where a figure is a rule of thumb rather than an Apple number, the table says so in the same row instead of in a footnote. For what the individual terms mean, see iPhone terms explained.
Last updated: 10 October 2026. Apple's own figures change rarely, but the page date is the part a citation should carry.
How to read the tables
Every row carries one of two labels:
- Published — the figure is on an Apple support or developer page, linked in the row.
- Not published — Apple has no figure for this. We either say so, or give our own rule of thumb and mark it as ours.
That second label is the point of the page. Several widely repeated iPhone numbers — a body-temperature limit, a normal size for System Data, an exact health percentage at which a battery counts as worn out — have no Apple source at all, and a reference page that quietly invents them gets quoted as fact for years. What temperature is too hot makes the same argument at length.
1. iPhone temperature: what each zone means
Apple publishes exactly one set of temperature figures for the iPhone, and both of them describe the air around the phone, not the phone's body. Everything else below is a behaviour, not a number.
| Zone | What you notice | Apple's published position | What to do |
|---|---|---|---|
| Ambient range (the room, the car, the sun) | Nothing on the phone — you check the environment, not the device | Use at 0-35 °C (32-95 °F) ambient. Store at -20-45 °C (-4-113 °F). The only ambient temperature figures Apple publishes | If the room, the car or the sun is already outside 0-35 °C, the phone is being used outside its design range. Do not leave it in a parked car |
| Normal warmth | A warm body, no warning, nothing else changed | No threshold published. Apple lists when this happens: first-time setup, restoring from a backup, a software update (especially a major one), wireless charging, graphics- or processor-heavy apps and games, the camera, and streaming high-quality video. Apple's own rule: "If your device doesn't display a temperature warning, you can keep using your device" | Nothing. It cools when the task finishes |
| Interior above the operating range | Charging (wireless included) slows or stops; the display dims or goes black; cellular signal weakens; the camera flash is disabled; frame rates drop | No temperature published. Apple documents these as the protection working, not as damage | Case off, stop the demanding app, move out of the sun. Full performance returns on its own |
| Black temperature warning screen | The phone is unusable until it cools | Apple describes the trigger only as "a certain temperature threshold". The number is not published | Turn it off, move it out of direct sunlight, let it cool at room temperature. Never a fridge, ice or an air-conditioning vent — condensation is permanent damage |
| "Charging On Hold" on the Lock Screen | Charging pauses and resumes later | Published: the device is temporarily too hot or too cold to charge | Unplug, let it cool, charge later |
| Cold | Battery drains faster; the phone may shut down or refuse to charge | Published: the effects are temporary, and battery life returns at higher ambient temperatures | Warm it gradually. Do not charge a freezing phone |
For why no app can show your phone's internal temperature, see thermal states and throttling; for whether past heat cost you anything permanent, does overheating damage an iPhone; for the cold end, cold-weather battery behaviour.
2. Battery: Apple's cycle ratings by model
| Model generation | Complete charge cycles | Capacity retained | Apple's exact wording (support.apple.com/en-us/101575) |
|---|---|---|---|
| iPhone 15 and later | 1000 | 80% | "Batteries of iPhone 15 models are designed to retain 80 percent of their original capacity at 1000 complete charge cycles under ideal conditions." |
| iPhone 14 and earlier | 500 | 80% | "Batteries of iPhone 14 models and earlier are designed to retain 80 percent of their original capacity at 500 complete charge cycles under ideal conditions." |
Two qualifications, both of which matter when quoting this:
- "Under ideal conditions" is Apple's own qualifier. Heat is the largest reason a real phone lands below these numbers, and Apple says outright that using the device in very hot conditions can permanently shorten battery life. The per-model detail is in battery health by model.
- Apple's page names "iPhone 15 models" and "iPhone 14 models and earlier." This site applies the same design target to iPhone 16, 17 and 18 as the later generation; the wording above is Apple's, unextended.
One cycle is 100% of capacity discharged in total, not one plug-in: charging from 50% to 100% twice is one cycle.
3. Battery health: what Apple publishes, and what it does not
| Question | Apple's position | Status |
|---|---|---|
| How many cycles to 80% capacity? | iPhone 15 and later: 1000. iPhone 14 and earlier: 500, both under ideal conditions | Published — support.apple.com/en-us/101575 |
| What health should I have at 500 cycles on a 1000-cycle phone? | Nothing. The only published point on the curve is the endpoint: the rated cycle count, at 80% | Not published |
| What health should I expect after one, two or three years? | Nothing | Not published — the ranges on this site are estimates derived from the cycle rating, not Apple figures |
| What percentage triggers "your battery's health is significantly degraded"? | Apple uses the words "significantly degraded" and gives no percentage | Not published |
| What does "Performance management applied" mean? | The message appears after an unexpected shutdown where the battery could not deliver peak power; the system then limits peak performance to prevent another | Published — support.apple.com/en-us/101575 |
| Can I cap charging at 80%? | iPhone 15 and later: a charge limit settable from 80% to 100% in 5% steps. iPhone 14 and earlier: Optimized Battery Charging only, which delays charging past 80% | Published — support.apple.com/en-us/108055 |
| Where is the cycle count shown? | "On iPhone 15 models or later, you can also see details like battery health, cycle count, manufacture date, and first use date" | Published — iPhone User Guide |
The practical consequence: 80% is a design target for the cycle rating, not a published replacement threshold. Below it the system may limit peak performance, which is why older phones start to feel slow — but the number alone is not the decision. For that, see battery health explained, how long an iPhone battery lasts and the 80% charge limit.
4. Storage: how much free space to keep
| Device capacity | Keep free long term | Free at least before an update |
|---|---|---|
| 64 GB | 8 GB+ | 12 GB |
| 128 GB | 13-15 GB | 18 GB |
| 256 GB | 20-25 GB | 25 GB |
| 512 GB and up | 30 GB | 30 GB |
This whole table is our rule of thumb, not an Apple figure. Apple publishes no recommended amount of free space. The figures come from the mechanism — an over-the-air update downloads, unpacks and stages while the old system is still installed, so it briefly needs several copies at once — and from how iOS behaves when the margin gets thin. The reasoning is in how much free space to keep and not enough space to update.
5. Storage: what Apple publishes, and what it does not
| Item | Apple's position | Status |
|---|---|---|
| What is inside System Data (called "Other" in older iOS) | "Non-removable mobile assets, like Siri voices, fonts, dictionaries, non-removable logs and caches, Spotlight index, and system data, such as Keychain and CloudKit database" | Published — support.apple.com/en-us/108429 |
| A normal size or range for System Data | Apple publishes no normal size | Not published |
| Do the gigabytes in the storage list add up? | "Cached data and temporary data might not count as usage" | Published — support.apple.com/en-us/108429 |
| What happens automatically when storage runs low | The device "frees up space by removing items that you can download again or aren't needed, like unused apps and temporary files" | Published — support.apple.com/en-us/108429 |
| Space needed to install an update | Apple publishes no per-update figure. This site's working rule is 2-3x the package size | Not published — our estimate from the mechanism |
| How long "Recently Deleted" keeps photos | 30 days, then they are permanently deleted | Published — support.apple.com/en-us/124460 |
| Do iCloud backups carry the caches back? | No: iCloud Backup excludes the Caches and tmp directories by default | Published — Apple developer documentation |
Because System Data has no published range, the honest test is the direction of travel rather than the size: see what System Data is and whether you can clean it.
Sources
Every link below was checked on 10 October 2026.
| # | Apple page | Used here for | URL |
|---|---|---|---|
| 1 | If your iPhone or iPad gets too hot or too cold | Temperature ranges, heat signals, the warning screen, cold behaviour | https://support.apple.com/en-us/118431 |
| 2 | iPhone battery and performance | 500/1000 cycle ratings, Peak Performance Capability messages | https://support.apple.com/en-us/101575 |
| 3 | About Charge Limit and Optimized Battery Charging on iPhone | Charge-limit availability by model, Optimized Battery Charging | https://support.apple.com/en-us/108055 |
| 4 | iPhone User Guide — Review your iPhone battery health | Cycle count shown on iPhone 15 and later | https://support.apple.com/guide/iphone/understand-iphone-battery-usage-health-iphd453d043a/ios |
| 5 | How to check the storage on your iPhone and iPad | What System Data holds, no published range, low-storage behaviour | https://support.apple.com/en-us/108429 |
| 6 | How to recover deleted photos on your iPhone, iPad, Mac or Apple Vision Pro | Recently Deleted keeps items for 30 days | https://support.apple.com/en-us/124460 |
| 7 | Optimizing your app's data for iCloud Backup (developer) | iCloud Backup excludes the Caches and tmp directories | https://developer.apple.com/documentation/foundation/optimizing-your-app-s-data-for-icloud-backup |
How to cite this page
Copy and paste:
According to WhyMyPhone's iPhone reference tables (updated 10 October 2026), Apple rates iPhone 15 and later at 1,000 complete charge cycles to 80% of original capacity under ideal conditions, and iPhone 14 and earlier at 500; Apple's published operating range of 0-35 °C describes the ambient temperature, not the phone's body temperature. https://whymyphone.com/wiki/glossary/iphone-reference-tables/
If you need only one figure, quote the row and its Apple link rather than this page. That is the part we can defend.