We live in an age where our smartphones are an extension of our lives — they keep everything organized for us, from phone numbers to banking information. But all smartphones have the same problem: they can only go so long on a single battery charge before having to be connected to a power source to recharge. Thankfully, there’s a gadget for that, too: a portable charger.

Portable chargers are small batteries that connect to your smartphone’s standard charging cable and deliver a refill anywhere. Portable chargers come in a variety of sizes — from the size of a tube of lip balm for a quick top off to a brick-size charger that can recharge your phone, tablet, and Bluetooth headphones all at the same time.

The biggest name in portable chargers is Anker, a company focused on power solutions ranging from outlets with USB ports to portable chargers of all shapes and sizes. If you’re looking for a portable charger that’s efficient and affordable, you’re going to want one from Anker. Here’s everything you need to know to pick out the right one and a few of our favorites, too.

Not sure where to start your search for an Anker portable charger? Begin by answering these questions to get a general sense of which models you should be looking at.

One of the biggest differentiators between portable chargers is the number of devices they can support simultaneously. Most of the models with smaller batteries are meant to only charge one device at a time, while the more expensive chargers with bigger batteries can sometimes charge up to three at once. Just keep in mind that charging multiple devices simultaneously usually means that they’ll get power more slowly than they would if they were plugged in one at a time.

If you’ll be using your Anker portable charger with multiple devices, it’s a good idea to get one with enough power to charge all of them at least once before needing to be plugged in itself. Spend some time determining how much power you’ll need in total before you start shopping.

Most devices connect to a portable charger with a USB 2.0 or USB 3.0 cable (keeping in mind that USB 3.0 can charge faster). Some cutting-edge portable chargers offer USB-C connections, which is even faster than USB 3.0. Before you buy an Anker portable charger, spend some time thinking about how you’ll be connecting your devices to it, and then make sure the one you buy supports the connectivity options you need.

There are two main metrics you can use to compare portable chargers: milliampere hours and amperage. Here’s what they mean:

Usually written as mAh, milliampere hours are how battery charge is measured. All portable chargers list how many milliampere hours the battery holds, and the batteries on your devices also tell you how many milliampere hours they can hold on a full charge. As a frame of reference, consider that the average smartphone has 3500 milliampere hours, and the average laptop battery has about 5000 milliampere hours.

A charger’s amperage indicates how quickly it can transfer power from its battery to your device. Amperage is measured in watts (W). Anker portable chargers come in different varieties, ranging from 2.5 watts to 10 watts. Most Anker chargers can also adapt to the device being charged, so it can always transfer charge as quickly as your device can receive it.

Inexpensive: Between $20 and $40, Anker offers some of its most convenient chargers, models that have enough power inside for a single smartphone charge and are still small enough to fit in a jacket pocket. If you need a portable charger for light to moderate use, or if you’re buying one to support just one device, you don’t need to spend more than this.

Mid-range: Between $40 and $60, you’ll find some of Anker’s biggest batteries and best values. In this price range, you can find portable chargers powerful enough to charge all of your devices a few times over. If you’re buying a battery for a ton of gadgets or just for disaster preparedness purposes, you’ll need to spend at least this much.

Expensive: Portable chargers that cost between $60 and $130 exist, but they’re not typically a great value. Models in this price range have batteries big enough to support laptops and include connectivity options like USB-C. If you absolutely need a portable charger with USB-C that can charge all of your devices at once, look in this price range.

• Check your devices to see how much power they’ll need. Picking the right capacity battery starts with knowing how much power you’ll need. Before you shop for a portable charger, look up each of your devices online, and note how big the battery is in milliampere hours (mAh). Add up the totals to see what capacity battery you’ll need to recharge them all at least once, and let that number guide your purchase decision.
• Keep an eye on how much each portable charger weighs. Anker portable chargers can weigh anywhere from a few ounces to a few pounds, so it pays to keep track. The weight will almost always correspond to the charger’s battery capacity — that is, the more capacious the battery, the heavier it is. If you plan on taking your charger with you every day, make sure you know what you’re signing up for in terms of weight, and don’t buy one that’s too heavy to carry around with you.
• Invest in short cables for use with your Anker portable charger. The cables that come with smartphones are usually pretty long, which is handy for many situations, but portable chargers don’t usually need the extra slack. Look for extra-short cables (usually three or six inches) for your devices so you can keep them all nearby while they’re charging without having to deal with a mess of tangled wires.

If you prefer portable chargers that can easily fit in your pocket, check out the Anker PowerCore 5000. It’s almost twice as heavy as Anker’s standard ultraportable charger, but that’s actually a good thing. It’s got a bigger battery inside, so it’s perfect for devices with bigger screens, like any of the “Plus” models offered by Apple, Samsung, and the like. If you need an Anker portable charger that goes anywhere and has more than a little oomph, take a long look at the PowerCore 5000. If you like the ultraportable models, but you need a charger that’s got an even bigger battery, consider the Anker Astro E1. It’s a middle ground between the company’s ultraportable models and its more traditional wallet-size models. The Astro E1 is the size of a deck of cards, it’s got a 6700 mAh battery, and it even supports Power IQ for super-fast charging. Best of all, it only weighs 4.4 ounces, so you can easily tote it anywhere without it weighing you down.

Q. What is Power IQ, and why does it matter?
A. A new trend is shaping up in the charge industry: technologies that can help batteries send power to devices much faster. Different companies use their own proprietary versions. For example, some devices and chargers support Quick Charge 3.0, while others use Power IQ. Anker makes portable chargers that support both Quick Charge and Power IQ, so your best bet is to check the devices you’ll be charging to see which version they support before you buy the corresponding Anker portable charger.

Q. Can I recharge my laptop battery with an Anker portable charger?
A. It depends. Most laptop batteries require you to plug them into a three-prong outlet in order to recharge — and as of this writing, none of Anker’s portable chargers include three-prong ports (although some competitors’ models do). That said, many newer laptops use USB-C cables to recharge their batteries, and Anker definitely has portable chargers that support USB-C. If you’re looking to buy a portable battery for your laptop, check to see what kind of plug it uses first to determine your options.

Q. How long does it take to recharge an Anker portable charger?
A. It varies by model, but in general, count on it taking between six and eight hours for most models. Some smaller models can charge in a few hours, but they typically don’t hold more than a single phone charge’s worth.