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Why Is My iPhone Charging So Slowly?

Most slow charging is ordinary — a low-power adapter, a worn cable, heat, or the phone protecting its battery. Not a broken phone.

You're probably here because the iPhone on your nightstand doesn't seem to fill up like it used to — or it's stuck at 80%, or it gained almost nothing after half an hour while you were using it. You're wondering whether the charger, the cable, the phone, or the battery is the problem, and whether you need to do something about it. Let's sort that out in a calm order.

Direct answer: most of the time, slow charging is one of four ordinary things — a charger or cable that can't deliver much power, the phone getting warm (it deliberately slows charging in heat), the phone's own battery-protection features pausing near the top, or heavy use while plugged in. Actual phone damage is rare. The first step is a two-minute test: use a known-good adapter and cable, in a cooler spot, with the phone locked, and see whether it charges normally. If it does, your phone is fine and the cause was something around it.

Before you worry, check the estimate

On iOS 26, your iPhone can tell you how long a charge will take — a far better yardstick than any fixed “30 minutes should get you X percent.” While it's charging, open Settings > Battery: it shows the estimated time to reach 80% (or to 100%, or your charge limit, if you're already above 80%), and the same estimate appears near the top of the Lock Screen.

That estimate already accounts for your iPhone model, charger, cable, temperature, current battery level, and what you're doing with the phone — so it tells you what's normal for your setup. If it says “about 40 minutes to 80%,” that's an honest number, not a fault. And if iOS shows a “Slow Charger” note (iOS 18 and later), that's an informational heads-up that a higher-wattage charger would help — it does not mean your iPhone or charger is broken.

Start with the two-minute test

Before you suspect the phone, change what's attached to it:

Use a different adapter and cable — ideally one you know works (from a friend, or one that fast-charges another phone).
Plug in somewhere cool, out of direct sun and away from soft surfaces that trap heat.
Lock the phone and leave it alone for a few minutes.

If it charges noticeably faster, the phone was never the problem — the charger, the cable, the heat, or the heavy use was. If it's still slow with a known-good setup, work through the reasons below.

The charger and cable are the usual suspects

How fast an iPhone fills depends heavily on what it's plugged into:

A low-power adapter charges slowly. An old 5W brick takes hours. For fast charging, many iPhone models need a 20W-or-higher USB-C Power Delivery adapter (Apple's own or a compatible one) with the right cable — and newer models can use even more: Apple notes that iPhone 17 models can reach about 50% in about 20 minutes with a 40W-or-higher adapter. So what counts as “fast” depends on your model and what it's plugged into — and real time still varies with the adapter, temperature, and what the phone is doing.
Cables matter. A worn, frayed, or damaged cable delivers less power even from a fast adapter. Non-certified cables are a gamble. If charging got slower around the same time a cable got beat up, try a different cable.
Wireless speed depends on what you're using. A MagSafe or Qi2-certified charger can charge fast on many iPhones — some current iPhone and MagSafe combinations support high-speed wireless charging — while an older low-power pad (under about 10W) is genuinely slow. Wireless also tends to run warmer than a cable, and in heat it can slow down further, which leads to the next point.

Heat: charging slows down on purpose

This is the one that surprises most people. When an iPhone gets warm, it intentionally slows charging to protect the battery. Apple's guidance is clear that charging can be limited or paused in heat. Signs you're in this situation:

The phone feels warm or hot while charging — especially on a wireless pad, in a case, in a hot car, or in the sun.
You see "Charging On Hold" on the Lock Screen. That's the phone pausing charging until it cools down — it's the phone protecting itself, not failing. Move it to a cooler spot and let it finish.

If heat is the cause, nothing is wrong with the phone. A cooler spot and a cable instead of wireless will usually speed it back up. See Why does my iPhone get warm when I'm not using it? for the full calm picture on warmth.

Slowing near the top is by design

If your phone charges fine to around 80% and then crawls — or stops — that's the iPhone protecting battery health, not a fault:

Optimized Battery Charging is on by default. When it expects you to stay plugged in for a long stretch, it pauses charging above about 80% and finishes closer to when you unplug. The Lock Screen may tell you when it will be full — press and hold that notification to pick "Charge Now" if you need it sooner.
Charge Limit (iPhone 15 and later) lets you cap charging at 80%, 85%, 90%, or 95% under Settings > Battery > Charging. If you (or a past you) set a limit, the phone simply stops at that level by design. It may occasionally top up to 100% briefly to keep its estimate accurate — also normal.
The very last few percent fill more slowly than the first 50% on nearly every phone. That's normal battery behavior, not a problem.

On iPhone 14 and earlier, the same settings live under Settings > Battery > Battery Health & Charging, and only Optimized Battery Charging is available.

Using the phone while it charges

A phone that's playing a video, navigating, or running a heavy app while plugged in is using power at the same time it's gaining it. With a modest charger, that can look like "it's not charging at all" — the battery may stay flat or even drop while the screen is on. Lock the phone, or give it a fast charger, and the percentage starts climbing normally again.

A simple way to decide

It charges fine with a known-good adapter and cable, in a cool spot, when locked → the phone is fine. The old charger or cable was the bottleneck.
It fills normally to about 80% then crawls, or stops at your chosen limit → that's the battery-protection features working. Nothing to fix.
It's warm and shows "Charging On Hold" → let it cool; that's the phone protecting itself.
It won't charge at all, charges only in one exact cable position, or gets very hot every time → that's when the charging port or hardware is worth checking.

The goal isn't to make you do more — it's to tell you when there's genuinely nothing to do. Most of these cases need no action at all.

You probably don't need to

Buy a new charger as the first step. Test with one you can borrow before spending anything.
Assume a slow charge means a dying battery. Battery age mostly affects how long a charge lasts, not usually how fast the phone fills — and the features above pause charging on purpose.
Panic about the "80% stop." It's Optimized Battery Charging doing its job. If you need full sooner, use the "Charge Now" option.
Charge it under a pillow, in a hot car, or in direct sun. Heat is the main thing that makes charging slow down, and it's the easiest to remove.

When to actually check further

A few situations are worth a closer look — not panic, just a check:

It never charges in any cable or charger → check the charging port for lint or damage, then try again.
"Charging On Hold" appears often in a normal, cool room → the phone is running hotter than it should; see Why does my iPhone get warm when I'm not using it?.
It gets very hot while charging even without heavy use → that's worth a support check.
If it's an older phone and battery life is also clearly dropping, battery health is the more relevant question — see Why does my iPhone battery drop so fast?.

If a check is warranted, that's the moment where a repair plan like AppleCare+ becomes relevant, not before — see Should I buy AppleCare+ for my iPhone? if you're weighing coverage.

What to do next

Not sure which of these fits your charging? Tell us what adapter and cable you're using, whether it's warm while charging, and where it seems to stall (via Ask Us) — we'll help you read it without the guesswork.