4 answers
★ Best answer
There is indeed some physics involved, but the phrase "works slower" oversimplifies things. Wireless charging through a case can be slower, but in most cases it's not critical, and it all depends on the material and thickness.
The magnetic field that transmits energy passes through plastic without any issues - it's not like radiation that lead blocks. But the thicker the case, the weaker the signal becomes. Some materials contain metal or carbon, which can actually weaken or scatter the field. Plus the air gap between the phone and the charger increases, and that directly affects how efficiently energy is transferred.
In practice, I've noticed that a thin silicone case barely slows down charging, but a thick one with a metal insert can. If your charging works fine through your case, there's no point changing it for this reason. But if you're getting a new case, it's worth checking it out in the store or reading reviews specifically about wireless charging compatibility before you buy.
The question kind of oversimplifies things - it's not so much about speed as whether wireless charging will work at all. A thick or metallic case can simply prevent the coils in your phone and charger from interacting properly, and then your device won't start charging at all or will constantly lose contact. But if the case is thin and metal-free, then yeah, the speed might drop slightly because of the distance between the coils, but it's usually not a big deal.
Practical tip: try putting your phone on the charger with the case facing up, then flip it case-side down - sometimes this helps you hit the right contact angle and speeds things up. If that doesn't work and charging is unstable, you could always temporarily take the case off just for charging, but if that's annoying, it's easier to just buy a thinner case or one specifically designed for wireless charging. A lot of phone manufacturers already sell those - they account for where the coils are positioned.
I tried wireless charging with different cases - and yeah, I actually did see an effect, but it's not as universal as it sounds in the first answer. The thing is, there are two different issues at play here, and people often lump them together. Yeah, there's physics involved: copper and other materials in the case create resistance to the magnetic field, and some energy gets lost as heat in the case itself. But it doesn't happen the same way with all cases.
A thick silicone case might slow down charging by like 10-20 percent, and your phone will heat up a bit more - it's noticeable, but not a big deal. But with metallic cases or ones where metal's woven into the fabric, it can be worse: charging might not turn on at all or work intermittently. At that point it's not really about speed anymore - it's that the magnetic coil just can't detect the charging station. I'd agree with the second answer on this one - the problem is bigger than just slow charging.
If you want to do it right - take the case off before charging, or look for thin cases without any metal. Manufacturers usually say in the instructions whether a case is compatible with wireless charging. From what I've noticed in practice, modern cases are already better designed for this than they used to be.
I just take the case off before charging, and that solves it completely - the coils line up perfectly against each other and charging works normally. If you don't want to take it off, try flipping your phone around on the charger different ways; sometimes the coils aren't centered and shifting it a couple centimeters makes a difference. And thinner cases definitely interfere with the signal less than thick ones with all those air pockets inside.
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