Where to find your battery health on iPhone

Your iPhone stores a battery health report that you can read yourself without any tools or apps. Open Settings, then tap Battery, then Battery Health & Charging. You will see a percentage labeled Maximum Capacity — this is the number that matters.

Maximum Capacity tells you how much charge your battery can hold right now compared to when it was brand new. A new iPhone shows 100%. As the battery ages, this number drops. You will also see a Health Status line that says either "Normal" or describes a condition like "Service Recommended" or "Service Battery."

This screen also shows Charging Optimization status, which is a separate feature that slows charging to protect the battery during overnight charging. That is not the same as battery health, though both appear on the same page.

Key Takeaways

  • Maximum Capacity percentage in Settings > Battery > Battery Health & Charging shows how much charge your battery can hold compared to when it was new.
  • A battery at 80% capacity or higher is considered normal; below 80% means the battery is aging faster than expected.
  • Health Status will tell you if Apple thinks the battery needs service before you see a major drop in capacity.
  • Maximum Capacity naturally drops 1% to 2% per year under normal use, so a two-year-old iPhone at 85% is typical.

What the percentage actually means

Maximum Capacity is not the same as your current battery level. If your Maximum Capacity is 85%, that means your battery can only hold 85% of the charge it held when new. If you charge to 100%, you are actually charging to 85% of the original capacity.

This affects how long your phone lasts between charges. An iPhone at 85% capacity will run about 15% shorter before the battery drains completely. The difference is noticeable but not dramatic — you might lose 20 to 30 minutes of screen time per day.

The percentage also reflects the total number of charge cycles your battery has been through. A charge cycle is one full drain and recharge, though partial charges count too. An iPhone battery is designed to retain 80% capacity after about 500 full charge cycles, which typically takes two to three years of normal use.

When Health Status shows a warning

If your Health Status says anything other than "Normal," Apple is flagging that your battery is degrading faster than expected. The most common message is "Service Recommended", which means the battery is still working but has degraded enough that Apple suggests you consider a replacement.

A message saying "Service Battery" means the battery has degraded significantly and you should get it replaced soon. Your phone will still work, but the battery may drain quickly or shut down unexpectedly even when the battery percentage shows charge remaining.

"Battery Unavailable" is rare and means the battery cannot be read properly — this usually requires service. None of these messages mean your phone is broken or unsafe. They mean the battery is no longer performing at its design standard.

How battery degradation happens

Lithium batteries degrade every time they charge, no matter what you do. Heat speeds up degradation significantly. If you regularly charge your phone in a hot car, use it while charging, or leave it in direct sunlight, the battery will age faster than the 1% to 2% per year you would see with normal use.

Letting the battery drain completely to 0% regularly also stresses it more than keeping it between 20% and 80%. Charging to 100% every single day wears the battery faster than letting it sit at 80% most of the time. However, these factors matter much less than the total number of charge cycles — a battery that has been through 1,000 cycles will show degradation no matter how carefully you treated it.

Fast charging generates more heat than standard charging, so it degrades the battery slightly faster. Wireless charging also generates more heat than wired charging. Neither is harmful in the short term, but over two or three years the difference becomes visible in your Maximum Capacity percentage.

Deciding whether to replace your battery

At 80% capacity, your battery is still within Apple's design specification and you have no urgent reason to replace it. Many people use iPhones at 75% to 80% capacity for months or years without problems. The choice depends on how much the shorter runtime bothers you.

At 70% capacity or below, you will notice the phone draining noticeably faster. If you are away from a charger for a full day, you may not make it to evening. This is when most people decide replacement is worth the cost and inconvenience.

If your Health Status shows "Service Recommended" or "Service Battery," Apple is telling you the battery is outside normal parameters. You can ignore this and keep using the phone, but you are closer to the point where unexpected shutdowns become likely. An Apple Store or authorized repair shop can replace the battery — the cost varies by iPhone model but typically ranges from $50 to $100.

What Charging Optimization does

The Charging Optimization setting on the same screen is a separate feature from battery health. When it is on, your iPhone learns your charging patterns and slows charging to 80% overnight, then finishes the last 20% closer to when you wake up. The goal is to keep the battery from sitting at 100% for hours, which degrades it slightly.

This feature does help extend battery lifespan, but the effect is small — maybe a few percentage points of capacity over a year. If you turn it off, your battery will degrade slightly faster, but not dramatically. The feature is on by default and most people leave it alone.

Frequently Asked Questions

Is 85% battery health bad?

No. A battery at 85% capacity is still within normal range and will work reliably for most people. You will notice slightly shorter runtime between charges, but the phone is not in danger. Most people do not replace a battery until it drops to 70% or below, or until Health Status shows a warning.

Can I improve my battery health percentage?

No. The percentage reflects physical wear to the battery and cannot be reversed by changing settings or charging habits. You can slow future degradation by avoiding heat and not letting the battery drain to 0% regularly, but the damage already done is permanent. Battery replacement is the only way to restore capacity.

Why did my battery health drop suddenly?

A sudden drop usually means the phone was exposed to heat or the battery went through several charge cycles in a short time. If it dropped 5% or more in a few days, check whether you have been charging in a hot environment or using the phone while charging. If the drop continues or Health Status shows a warning, the battery may be failing and should be checked by Apple.

Does closing apps or turning off background refresh help battery health?

No. Those settings affect how fast your battery drains during the day, not how fast it degrades over time. Battery health is determined by charge cycles and heat exposure, not by how you use the phone. You can extend runtime by closing apps, but it will not improve the Maximum Capacity percentage.

Should I replace my battery before I sell my iPhone?

That depends on the buyer and the price difference. A phone with 80% battery health will sell for slightly less than one at 100%, but the difference is usually $20 to $50. If a battery replacement costs $70 to $100, it may not be worth doing before sale. If the battery is at 60% or below, replacement might increase the resale value enough to justify the cost.