Danny Weber
Modern iPhone and iPad models can charge much faster than old 5W or 20W adapters allow. Here is what power level actually makes sense.
When people talk about iPhone or iPad battery life, they usually start with power consumption. Which apps drain the battery fastest, how many notifications arrive every day, what screen brightness is set and how many apps are running in the background — all of this really affects runtime. But there is another factor that is easy to underestimate: charging speed.
Sometimes it matters almost as much as battery capacity itself. A phone can be nearly dead before leaving home, with only 15–20 minutes near a wall outlet. With an old adapter, that time may add only a few percent. With a fast charger, the same iPhone can recover far more energy — enough to get through the commute to the office, university or airport.
The problem is that many iPhone and iPad owners do not know the maximum charging power their device supports. Apple does not always put this information in the most visible place in consumer specs, and a charger has not been included with new iPhones for years. As a result, people buy fresh smartphones but keep charging them with old 5W, 12W or 18W adapters, without realizing they are cutting the speed themselves.
To understand how quickly an iPhone or iPad can charge, it helps to know two basic numbers: battery capacity and charging power.
Battery capacity is usually measured in milliamp-hours — mAh. In simple terms, this figure shows how much energy the battery can deliver before it runs flat. For example, a 1000 mAh battery could theoretically supply 1000 milliamps of current for one hour.
Real life is more complicated. A smartphone does not consume energy evenly: camera use, games, navigation, mobile data, a bright screen and video calls all drain the battery differently. Some devices also use energy more efficiently than others. That is why two models with similar battery capacities can last for different amounts of time.
Still, capacity gives a general idea of battery size. Large modern smartphones often sit around 5000 mAh, while tablets can approach 10,000 mAh. For example, the large iPhone 17 Pro Max is listed with a 5088 mAh battery, while the base iPhone 17 has 3692 mAh. The 11th-generation iPad is estimated at about 7698 mAh, and the 13-inch iPad Pro with the M5 chip at roughly 10,290 mAh.
Charging speed is measured not in mAh, but in watts. The higher the wattage, the faster a charger can deliver energy to the battery — as long as the device itself supports that speed.
It may seem strange that a laptop can charge from a 100–140W adapter while a smartphone charges much more slowly. The reason is not only manufacturer caution or cable limits. It comes down to battery size, heat and safety.
Larger devices have bigger batteries, often made of several cells. They have more room to dissipate heat, and the body can fit a more serious cooling system. That is why a MacBook or another laptop can accept 100W or more without an excessive overheating risk.
In a smartphone, everything is far more compact. The battery sits in a thin body next to the processor, screen, cameras and other components. Fast charging generates heat, and overheating is bad for the battery. That is why manufacturers increase charging power carefully and use complex algorithms: the device charges faster at first, then slows down as it approaches 80–100 percent.
Modern standards such as USB Power Delivery have improved the situation a lot. Even smaller devices can now charge faster than before. Some Android phones already support impressive numbers: the OnePlus 15, for example, reaches up to 120W with the company’s SuperVOOC standard. Apple looks more cautious by comparison, but charging speeds for iPhone and iPad are also gradually rising.
With the latest iPhone generations, Apple has not made a radical leap, but there is still progress. According to available data, current iPhone 17 models can charge from an adapter with up to 40W of power. That is already much faster than old Apple chargers and convenient enough for short top-ups during the day.
iPhone Air stands apart. Because of its thin body, this model is limited to 20W. That is one of the compromises required for such a slim design. It can still be plugged into a modern adapter, but super-fast charging is not on the menu: the phone will not take more than its design allows.
One thing is important here: connecting an iPhone to a higher-power charger does not mean it will charge dangerously fast. The device controls how much power it accepts. If a phone supports a maximum of 40W, a 65W or 100W adapter will not force it to charge at 100W. It will simply provide the power the device asks for, and the rest of the capacity remains unused.
Many iPhone owners keep using adapters left over from older devices. It is convenient: the charger works, the cable fits and the phone charges. But the speed may be far from the maximum.
The last iPhones that shipped with a power adapter had fairly modest blocks. The iPhone 11 came with a 5W adapter, while the iPhone 11 Pro had an 18W one. That was acceptable for its time, but for modern devices these power levels look weak.
Connect a new iPhone to an old 5W charger and it will charge very slowly. This is especially noticeable when the battery is nearly empty and time is short. Instead of recovering a meaningful amount of charge, the user gets a few percent and the feeling that the phone is “charging forever”.
That is why, after buying a new iPhone, it is worth checking not only the phone itself but also the power adapter. The real bottleneck may not be the battery at all, but the small white brick that has been sitting in a drawer for years.
With iPad, the situation is even more interesting. Tablets are larger than phones, their batteries are bigger, and fast charging matters even more. An iPhone can be topped up reasonably quickly even from a weak adapter, but a large iPad with a battery around 10,000 mAh will spend a long time charging from a low-power block.
The base iPad released in 2025 supports charging at up to 45W. That is already a solid figure, comparable with some rival tablets.
The new iPad Pro with the M5 chip can charge even faster — up to 60W. For a professional tablet, that makes sense: such devices are often used for work, drawing, editing, presentations, travel and partial laptop replacement. The faster they recover charge, the more convenient they become.
But there is an annoying catch. Unlike the iPhone, iPad can still come with a charger in many configurations. However, the bundled adapter does not always unlock the maximum charging speed of a particular model. In other words, the tablet may support 45W or 60W, but the charger in the box does not reveal that potential. The result is a device that can theoretically charge much faster but spends extra time at the wall in everyday use.
The iPad example shows an important rule: maximum charging speed does not depend only on the device. Three compatible parts are needed: the gadget itself, the power adapter and the cable.
If an iPad Pro supports 60W but is plugged into a 20W adapter, it will charge roughly within the adapter’s limits. If a powerful charger is paired with the wrong cable, the result can also be worse than expected. And if the device itself is limited to 20W, like iPhone Air, buying a 100W adapter will not work miracles.
So when choosing a charger, it is not enough to look at a shiny “fast charging” label. The real specs matter: maximum power, USB Power Delivery support and how power is split between ports if there are several. For example, some multi-port adapters may have a total output of 65W, but when two or three devices are connected, that power is divided between ports. A laptop, iPad and iPhone connected at the same time may each receive less power than expected.
For modern iPhone 17 models, except iPhone Air, it makes sense to choose a charger rated at at least 40W. A more powerful adapter — for example 65W — is also fine, especially if it will charge not only a phone but also a tablet, laptop or several devices at once. For iPhone Air, a 20W adapter is enough because the phone itself is limited to that power. A stronger charger will not hurt, but it will not noticeably speed things up.
For the base 2025 iPad, it is best to look at chargers from 45W. For iPad Pro M5, start from 60W. If one adapter is meant to serve both a tablet and a laptop, models rated at 65–100W with several USB-C ports are worth considering.
Apple sells its own fast adapters, but they are not the only option. Chargers from Anker, Ugreen, Satechi and other brands are widely available. The main thing is to choose quality models from known brands, check the required standards and avoid suspiciously cheap power bricks.
Fast charging can indeed heat the battery more, and heat is one of the factors that ages a battery. A slower adapter can therefore be a little gentler in some situations, especially if the device charges overnight and speed does not matter.
But modern iPhone and iPad models use power controllers that regulate the process. Charging does not stay at maximum power all the time. The device usually fills up faster at the beginning, then gradually reduces the rate, especially near a full charge.
A reasonable approach looks like this: for overnight charging, a regular adapter is fine or optimized charging can be enabled; for short daytime top-ups, a fast power brick is useful. That gives a balance between convenience and battery care.
Many users buy a new iPhone or iPad and keep charging it with an old adapter, wondering why the process takes so long. Often the problem is not the gadget, but the accessory. If an iPhone supports 40W and a 5W charger is used, only a small part of the possible speed is available. If an iPad Pro can accept 60W but is connected to a 20W adapter, the tablet will charge much more slowly than it could.
Before buying a new charger, the simple rule is worth remembering: the adapter’s power should be no lower than the maximum charging power of the iPhone or iPad. More is fine; less means slower.
Fast charging does not turn a phone or tablet into an endless device, but it makes everyday use much more convenient. Sometimes an extra 20–30 percent gained quickly decides whether there is enough battery for a trip, meeting, shoot, lecture or workday. And if an iPhone or iPad can already charge faster, there is little sense in keeping it stuck in the era of old 5W adapters.
© A. Krivonosov