The Envirofone iPhone Battery Health Index · September 2026
How much life is left in a traded-in iPhone's battery?
We measured battery health and completed charge cycles on 37,413 iPhones traded in to Envirofone, taken from the first diagnostic test each handset received on arrival. Across 29 models, this is how much charge is left, and which iPhones fade fastest.
- Tested since
- Updated
- First diagnostic reading on arrival, before any repair
The headline numbers
Ready to quote
Needs a new battery
67%
67% of every iPhone 11 traded in to us arrives below Apple's 80% service threshold, the highest share of any iPhone we measured.
Across every model
40%
Across 37,413 iPhones, 40% were already below the threshold at which Apple advises a battery replacement.
The cost of a charge
26 points
Median battery health falls from 100% under 100 charge cycles to 74% beyond 2,001.
How hard we charge
214 a year
The typical traded-in iPhone had run about 214 full charge cycles for every year since its launch.
Chart 1 · The curve
How iPhone batteries fade with charge cycles
| Charge cycles | Devices | Median health |
|---|---|---|
| 1-100 | 1,314 | 100% |
| 101-250 | 1,424 | 99% |
| 251-500 | 3,957 | 89% |
| 501-800 | 7,746 | 86% |
| 801-1,200 | 10,799 | 81% |
| 1,201-2,000 | 10,914 | 77% |
| 2,000+ | 1,259 | 74% |
Chart 2 · The service threshold
Which iPhones arrive needing a new battery
| Model | Needs a battery |
|---|---|
| iPhone 11 | 67.2% |
| iPhone 12 mini | 61.9% |
| iPhone 11 Pro | 60.9% |
| iPhone 11 Pro Max | 59.9% |
| iPhone 12 Pro | 58% |
| iPhone SE (2nd Gen) | 57.6% |
| iPhone 8+ | 55.6% |
| iPhone 13 Pro | 52.9% |
| iPhone 12 Pro Max | 52.9% |
| iPhone X | 48.5% |
| iPhone 12 | 45.4% |
| iPhone 7 | 44.7% |
| iPhone 13 mini | 44.4% |
| iPhone 8 | 42.5% |
| iPhone 13 | 39.6% |
| iPhone XR | 37.8% |
| iPhone 13 Pro Max | 29.3% |
| iPhone 14 Pro | 27.7% |
| iPhone 14 | 15.9% |
| iPhone 14 Pro Max | 13.9% |
| iPhone SE (3rd Gen) | 10.3% |
| iPhone 14 Plus | 8.4% |
| iPhone 15 | 5.9% |
| iPhone 15 Pro | 2.2% |
| iPhone 15 Pro Max | 2.1% |
| iPhone 15 Plus | 0.7% |
| iPhone 16 Pro Max | 0.3% |
| iPhone 16 Pro | 0% |
| iPhone 16 | 0% |
Chart 3 · By generation
How each iPhone generation has aged
| Model | Median age (years) | Median health | Devices |
|---|---|---|---|
| iPhone 16 Pro Max | 1.4 | 96% | 383 |
| iPhone 16 Pro | 1.6 | 92% | 306 |
| iPhone 16 | 1.7 | 93% | 304 |
| iPhone 15 Pro | 2.4 | 87% | 948 |
| iPhone 15 Pro Max | 2.4 | 87% | 875 |
| iPhone 15 Plus | 2.5 | 88% | 272 |
| iPhone 15 | 2.6 | 87% | 1,492 |
| iPhone 14 Pro | 3.2 | 83% | 1,120 |
| iPhone 14 Pro Max | 3.2 | 84% | 931 |
| iPhone 14 | 3.4 | 85% | 2,407 |
| iPhone 14 Plus | 3.4 | 85% | 368 |
| iPhone SE (3rd Gen) | 4 | 87% | 439 |
| iPhone 13 Pro Max | 4.3 | 83% | 702 |
| iPhone 13 Pro | 4.5 | 79% | 1,249 |
| iPhone 13 mini | 4.5 | 81% | 923 |
| iPhone 13 | 4.6 | 82% | 4,400 |
| iPhone 12 Pro Max | 5.1 | 79% | 554 |
| iPhone 12 Pro | 5.2 | 79% | 1,041 |
| iPhone 12 mini | 5.3 | 78% | 1,013 |
| iPhone 12 | 5.4 | 80% | 5,398 |
| iPhone SE (2nd Gen) | 5.7 | 78% | 1,208 |
| iPhone 11 Pro | 6.1 | 75% | 506 |
| iPhone 11 Pro Max | 6.2 | 77% | 362 |
| iPhone 11 | 6.5 | 76% | 5,691 |
| iPhone XR | 7.1 | 81% | 1,597 |
| iPhone X | 7.9 | 80% | 375 |
| iPhone 8 | 8.1 | 81% | 809 |
| iPhone 8+ | 8.1 | 79% | 234 |
| iPhone 7 | 9.6 | 81% | 394 |
Every model
Every iPhone we measured
| Model | Devices | Median health | Median cycles | Needs a battery | Median age | Cycles a year |
|---|---|---|---|---|---|---|
| iPhone 12 Pro | 1,041 | 79% | 1,340 | 58% | 5.2 yrs | 256 |
| iPhone 11 Pro | 506 | 75% | 1,300.5 | 60.9% | 6.1 yrs | 214 |
| iPhone XR | 1,597 | 81% | 1,297 | 37.8% | 7.1 yrs | 182 |
| iPhone 11 Pro Max | 362 | 77% | 1,223.5 | 59.9% | 6.2 yrs | 197 |
| iPhone 12 mini | 1,013 | 78% | 1,212 | 61.9% | 5.3 yrs | 231 |
| iPhone 11 | 5,691 | 76% | 1,194 | 67.2% | 6.5 yrs | 184 |
| iPhone 8+ | 234 | 79% | 1,175 | 55.6% | 8.1 yrs | 146 |
| iPhone 12 | 5,398 | 80% | 1,172 | 45.4% | 5.4 yrs | 217 |
| iPhone X | 375 | 80% | 1,169 | 48.5% | 7.9 yrs | 147 |
| iPhone 12 Pro Max | 554 | 79% | 1,166 | 52.9% | 5.1 yrs | 229 |
| iPhone 13 Pro | 1,249 | 79% | 1,090 | 52.9% | 4.5 yrs | 244 |
| iPhone 8 | 809 | 81% | 1,071 | 42.5% | 8.1 yrs | 133 |
| iPhone SE (2nd Gen) | 1,208 | 78% | 1,038 | 57.6% | 5.7 yrs | 181 |
| iPhone 13 mini | 923 | 81% | 1,023 | 44.4% | 4.5 yrs | 229 |
| iPhone 13 | 4,400 | 82% | 987 | 39.6% | 4.6 yrs | 217 |
| iPhone 7 | 394 | 81% | 903 | 44.7% | 9.6 yrs | 94 |
| iPhone 13 Pro Max | 702 | 83% | 873 | 29.3% | 4.3 yrs | 203 |
| iPhone 14 Pro | 1,120 | 83% | 831 | 27.7% | 3.2 yrs | 256 |
| iPhone 14 | 2,407 | 85% | 749 | 15.9% | 3.4 yrs | 219 |
| iPhone 14 Pro Max | 931 | 84% | 730 | 13.9% | 3.2 yrs | 225 |
| iPhone 15 Pro | 948 | 87% | 669.5 | 2.2% | 2.4 yrs | 279 |
| iPhone 14 Plus | 368 | 85% | 632.5 | 8.4% | 3.4 yrs | 188 |
| iPhone 15 | 1,492 | 87% | 612 | 5.9% | 2.6 yrs | 231 |
| iPhone 15 Pro Max | 875 | 87% | 551 | 2.1% | 2.4 yrs | 229 |
| iPhone 15 Plus | 272 | 88% | 501.5 | 0.7% | 2.5 yrs | 202 |
| iPhone SE (3rd Gen) | 439 | 87% | 486 | 10.3% | 4 yrs | 122 |
| iPhone 16 Pro | 306 | 92% | 398 | 0% | 1.6 yrs | 254 |
| iPhone 16 | 304 | 93% | 354.5 | 0% | 1.7 yrs | 205 |
| iPhone 16 Pro Max | 383 | 96% | 280 | 0.3% | 1.4 yrs | 199 |
The method
How we worked it out
How we measured this
Every device traded in to Envirofone is run through a PhoneCheck diagnostic on arrival, before anything is repaired or refurbished. This index uses that first test only, one reading per trade-in order, for iPhones traded in by members of the public since 1 June 2024. The 20 September 2026 edition covers 37,413 devices across 29 models.
What we excluded, and why
Some handsets never return a real battery reading. PhoneCheck records those as zero charge cycles, and confusingly still reports a battery health of 100%, so keeping them in would invent a population of perfect batteries. We dropped 1,201 readings on that basis. We also check for a cycle counter that has overflowed to an impossible value; that rule caught none in this edition. We also check for a health field PhoneCheck could not parse; that rule caught none in this edition.
In total we dropped 1,201 readings out of 38,614 first tests, about 3.1%, keeping 37,413 devices across 29 models in this edition.
PhoneCheck also runs on devices that were never a customer trade-in at all: bulk supplier stock, partner units, and stock we already owned being retested. 68,813 such tests sit in our PhoneCheck history outside this index. They are not counted among the exclusions above, because they were never candidates for this index in the first place.
A model needs at least 200 devices tested before we publish a figure for it. That holds back 19 models in this edition.
What this does and does not tell you
People trade in phones they have stopped enjoying, and a tired battery is one of the reasons people upgrade. This index describes iPhones traded in to us, not the whole installed base, and it will read worse than the installed base as a result.
Roughly 99% of these readings were taken from 2025 onwards, so the index compares devices of different ages measured at the same point in time. It does not track a single model as it ages.
Battery health as reported by iOS is the device's own modelled estimate of remaining capacity against its original design capacity, not a laboratory measurement. 80% is the level at which Apple itself advises a replacement.
Why iPhone only
Android handsets report charge cycles in coarse steps rather than exact counts: 63.8% of the non-Apple cycle counts we hold are exact multiples of 40, against 2.3% for iPhone. The samples are also far thinner once split by model. Publishing the two side by side would suggest a comparison the data cannot support, so this index covers iPhone only.
What each column means
The CSV has one row per iPhone model, not per device: this edition has 29 rows, not tens of thousands. Each row aggregates every device counted in its devices column, so a downstream reader working from the file sees a model summary, never an individual handset.
| Column | Definition |
|---|---|
model | The iPhone model, as PhoneCheck reports it at test time. |
devices | Devices traded in to Envirofone and included in this edition. |
mean_health_pct | Mean battery health, as a percentage of design capacity. |
median_health_pct | Median battery health, as a percentage of design capacity. |
median_cycles | Median completed charge cycles at the first test. |
need_service_pct | Percentage below 80%, the level at which Apple advises a battery replacement. |
launched | UK launch date, from Apple's press releases. |
median_age_years | Median device age in years when tested. |
cycles_per_year | Median cycles divided by median age, to the nearest whole cycle. |
Use this data
The index is published under a Creative Commons Attribution 4.0 licence. Reuse any of it, including commercially, as long as you credit it:
Source: Envirofone iPhone Battery Health Index, September 2026, envirofone.com
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How iPhone batteries fade with charge cycles
<iframe src="https://www.envirofone.com/en-gb/iphone-battery-health/embed/curve" width="100%" height="520" style="border:0;max-width:760px" title="How iPhone batteries fade with charge cycles (Envirofone)" loading="lazy"></iframe>
<p>Source: <a href="https://www.envirofone.com/en-gb/iphone-battery-health">Envirofone iPhone Battery Health Index</a></p>Which iPhones arrive needing a new battery
<iframe src="https://www.envirofone.com/en-gb/iphone-battery-health/embed/service" width="100%" height="520" style="border:0;max-width:760px" title="Which iPhones arrive needing a new battery (Envirofone)" loading="lazy"></iframe>
<p>Source: <a href="https://www.envirofone.com/en-gb/iphone-battery-health">Envirofone iPhone Battery Health Index</a></p>How each iPhone generation has aged
<iframe src="https://www.envirofone.com/en-gb/iphone-battery-health/embed/ageing" width="100%" height="520" style="border:0;max-width:760px" title="How each iPhone generation has aged (Envirofone)" loading="lazy"></iframe>
<p>Source: <a href="https://www.envirofone.com/en-gb/iphone-battery-health">Envirofone iPhone Battery Health Index</a></p>Press enquiries
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