How we decided

A selection of the chargers we tested.

We quickly whittled down an initial list of 45 chargers by knocking out those that had only one or two high-speed-charging ports (except for super-compact chargers, mentioned below); had no high-speed-charging ports at all; or had a mix of faster- and slower-charging ports, requiring you to figure out which one is the "right" port if you want to charge your tablet as fast as possible.

We brought in 18 units for hands-on testing. First we connected an iPad Air 2 to a USB ammeter, a tool that measures power transfer. Then we went through each port -- 83 in all -- and measured the electrical output of each, looking for figures around 2.4 amps, the maximum power draw of the tablet.

Testing our step-up pick, Anker's 60W charger, with six full-size iPads.

We tested the remaining chargers with a collection of six iPads to ensure that the power draw didn't drop as we added more devices. After verifying that each USB cable we were using could handle the maximum possible current, we used our ammeters to measure the average draw of an original iPad Air and a fourth-generation iPad -- the models that draw the highest current -- on each charger while keeping the other ports on that charger connected to the remaining iPads.

Our pick

The Anker 36W charger occupies only a single wall outlet when plugged in.

Anker's 36W 4-Port USB Wall Charger is the best multiport USB charger for most people. It's the most powerful charger that plugs directly into a wall outlet, letting you fast-charge up to three full-size iPads at once or four at a slower rate. (Alternatively, you can fast-charge two iPads and two smartphones.) It's also physically small compared with the competition, and it's quite affordable. Finally, Anker is a company that has built a strong reputation in the mobile-accessory field with well-designed products that often work better than the competition, usually at lower prices.

The circuitry in the charger can tell whether you're plugging in a smartphone, a tablet, or another device, and whether it's Android, iOS, or something else; it then delivers the appropriate amount of current for the fastest charging speed.

The runner-up

You have to provide your own cables, but there are enough ports for the entire family.

Although four charging ports is a lot, some people will need even more. Anker's 60W 6-Port Family-Sized Desktop USB Charger ($36) is the best option for them. It's considerably more powerful than the Anker 36W, and it offers two additional ports. Instead of plugging directly into an outlet, it uses a 5-foot cord.

A tiny travel pick

The same amount of power in a much smaller size.

For an impressive amount of power in a tiny package, we recommend Aukey's 12W / 2.4A Home Travel USB Wall Charger. You get as much juice as you would with Apple's iPad charger and an extra charging port, in a much smaller package -- a scant 1.4 by 1.2 by 1.2 inches with its prongs folded infor half the price.

In closing

Anker's 36W 4-Port USB Wall Charger is the best multiport charger for most people, but you can find other good options depending on the number and kinds of devices you need to charge.

This guide may have been updated. To see the current recommendation, please go to TheWirecutter.com.