How Big a Power Bank Do I Need: A Practical Guide

If you’re planning to own a power bank, you have to decide on the power capacity that suits your needs. It’s because power banks have varying ratings on their labels, such as 5000mAh, 10000mAh, or 20000mAh. If you don’t know what to look for, you will end up wasting money. This is why it’s important to know the answer to your question, “How big a power bank do I need?”

If you choose a power bank that is too small, it won’t give your device enough charge when you need it the most. If you get one that’s too large for your actual needs, you may be carrying extra weight and paying more for capacity you rarely use. This guide will help you figure out how big a power bank you need, key features to look for, and the best power banks in 2025.

 

alt: Anker Prime 27650mAh Power Bank

Power Bank Capacity mAh Explained

Before answering the question, “How big a power bank do I need? you need to understand what mAh or milliampere-hours means. This number tells you how much charge a power bank can store and deliver to your devices. The higher the mAh, the more power you can get. Here are the basic capacity ranges and what they mean:

• 5,000mAh to 10,000mAh:This range is ideal if you only need one or two full smartphone charges while outdoors. A 5,000mAh power bank might give smaller phones a full charge, but it won’t be enough for larger phones or multiple uses. These are great if you want something compact to slip into a pocket or purse for emergencies or light daily charging.
• 10,000mAh to 20,000mAh:This is another answer to the question, “How many mAh is a good power bank?” It’s a reliable range for everyday routine tasks without too much bulk. You can charge your phone two to three times, depending on the model. These are ideal if you often rely on your phone for navigation, video calls, or work.
• 20,000mAh and above:This size is for people who carry multiple devices or travel frequently. They can power tablets, phones, and even laptops with the right ports. However, they are bulkier and may take longer to recharge. Keep in mind that power banks above 27,000mAh may not be allowed in carry-on luggage on airplanes due to safety regulations.

How to Choose a Power Bank with the Right Capacity

Let’s answer the question, “How big a power bank do I need?” The answer depends on what devices you use, how often you charge them, and whether you prioritize portability or long-lasting power. Here’s how to choose a power bank that meets your needs:

1. Know Your Device’s Battery Size

Check the battery capacity of your phone, tablet, or other gadgets. Most modern smartphones have batteries ranging from 3,000mAh to 5,000mAh. If your device has a 4,000mAh battery, a 10,000mAh power bank can deliver one to two full charges, minus energy loss. This gives you a clear starting point when estimating how much capacity you really need.

2. Consider How Often You Recharge

If you charge once a day or only during emergencies, a 10,000mAh power bank is enough. But if you use your device continuously for work, travel, or navigation, go for 15,000mAh to 20,000mAh. These sizes can support multiple charges and are more reliable for daily use. Larger capacities also make more sense if wall access is limited.

3. Understand Actual Usable Capacity

All power banks lose some energy during charging due to heat and voltage conversion. On average, only 70% to 80% of the labeled capacity reaches your device. That means a 10,000mAh power bank delivers 7,000mAh to 8,000mAh. Considering this loss helps answer your question, “How much mAh should a power bank have?”

4. Think About the Number of Devices

If you’re charging more than one device, such as a smartphone, wireless earbuds, or tablet, you will need a high-capacity power bank. A 20,000mAh power bank can handle multiple devices and still last through the day. Low-capacity power banks may run out quickly if you share or rely on them for multiple devices. Go higher if you're using devices with large batteries.

5. Consider Portability

A larger power bank offers more charging times but is heavier and takes longer to recharge. Smaller models are easier to carry but provide limited backup. Ask yourself if you’re okay with the added weight for more convenience or if you prefer lightweight options for quick emergencies. This balance helps guide your choice based on real-world use.

alt: Anker Prime 27650mAh Power Bank

Beyond Capacity Key Features to Consider when Choosing a Power Bank

At this point, you now have the answer to your question, “How big a power bank do I need?” After deciding on the power bank capacity you want, think about the features of the power bank you will buy. Here are the key features to consider when choosing a power bank:

1. Charging Speed

Fast charging can make a big difference, especially when you’re in a rush. Look for power banks that support Power Delivery (PD) or Quick Charge (QC) to charge your phone faster than standard ports. Most phones today can accept higher wattages, so a power bank with 18W or higher output ensures shorter waiting time. If you charge tablets or newer phones, this is a must.

2. Recharging Time

The time it takes to recharge the power bank itself also matters. A 20,000mAh power bank using a basic micro-USB input can take over 10 hours to fill up. If you want quicker turnaround, choose a model with USB-C input and PD support, which can recharge in as fast as 3 to 5 hours depending on the wall charger used. This is practical if you rely on your power bank daily.

3. Number of Ports

More ports give you the option to charge multiple devices at once, but the type of port is just as important. USB-C is now the standard for both input and output on newer devices, offering better compatibility and faster charging. USB-A is still useful for older devices, so having both gives you flexibility. Some power banks even include AC outlets or wireless pads for added versatility.

4. Size and Portability

Power banks with higher capacities are naturally bulkier, but not all are designed well. Before buying, check the actual dimensions and weight to see if it fits your routine. A slim, well-balanced design is easier to carry in your bag or even your coat pocket. If you’ll be using it while commuting or traveling, size matters just as much as power.

5. Safety Features and Certifications

Any power bank you choose should have built-in protection features like overcharge, short circuit, and temperature control. This is especially important in cold Canadian winters or during summer heat waves, where battery safety can be a concern. Look for certifications, and avoid unknown brands without quality control standards.

Best Power Banks in 2025

You have learned the answer to your question, “How big a power bank do I need?” This includes how to choose a power bank with the right capacity and key features to look for in a power bank.  You can now make informed decisions, and if you want specific recommendations, below are some of the best power banks in 2025:

1. Anker Prime 27650mAh Power Bank

The Anker Prime 27650mAh Power Bank is one of the most high-capacity power banks available at Anker. Despite its high capacity, it's surprisingly compact and perfect for air travel’s 100Wh threshold. It features multiple USB-C and USB-A ports, allowing you to charge up to three devices at once, including laptops. It also has an intelligent display that shows real-time charging stats.

alt: Anker Prime 27650mAh Power Bank

Battery Capacity: 27,650mAh (99.54Wh)

Flight-Friendly: Yes

Key Features: 250W Output, Super-Fast Recharge, Smart Power Display, App Control, Active Temperature Control

2. Anker Power Bank (20K）

If you don’t want to carry cables around, the Anker Power Bank (20K) is for you. It offers a strong balance of size and performance, making it suitable for daily use. It has a built-in USB-C cable for your Android device or iPhone, along with a USB-C port and a USB-A port. What makes this stand out is that the built-in USB-C cable is fast-charging and can endure repetitive bending.

alt: Anker Power Bank 20000mAh

Battery Capacity: 20,000mAh (74Wh)

Flight-Friendly: Yes

Best For: Daily phone users, students, and commuters

Key Features: 87W Output, Built-In Fast-Charging USB-C Cable, Triple-Device Charging, Compact

3. Anker Nano Power Bank

Another option if you don’t want the clutter of cables is the Anker Nano Power Bank. What makes it unique is its pocket-sized design that is minimalist, stylish, and ultra-compact. It has a built-in foldable USB-C connector that plugs directly into your Android phone or iPhone. Although it only holds 5,000mAh, it’s ideal for quick top-ups during the day when you're away from an outlet.

alt: Anker Nano Power Bank

Battery Capacity: 5,000mAh (18.5Wh)

Flight Friendly: Yes

Key Features: 22.5W Output, Built-in Foldable USB-C Connector, Pocket-Sized Design, Fast-Charging, Dynamic Temperature Sensor

Conclusion

In this article, you have learned the answer to your question, “How big a power bank do I need?” Choosing a power bank doesn't have to be confusing. Whether it’s a 5,000mAh for quick top-ups or a 20,000mAh power bank for extended use, the right size depends on your lifestyle. Consider the tips discussed in this article on how to choose the right capacity and the key features to look for in a power bank. If you’re looking for suggestions, consider also the listed best power banks in 2025 from Anker. With the right information, you can pick a power bank that is both practical and reliable.

FAQs

Should I get 10,000mAh or 20,000mAh power bank?

Choose 10,000mAh if you only need to charge your phone once or twice during the day and want something light to carry. If you often travel, use multiple devices, or need more backup, 20,000mAh gives you more flexibility and charging times.

Is a 20000mAh power bank too much?

Not necessarily. It’s bulkier than smaller models, but if you use high-powered devices like tablets or laptops, or spend long hours away from home, the extra capacity is useful. While it’s typically bulky, some trusted brands like Anker offer models that are slim or compact.

Is a 5000 or 10000mAh power bank better?

Between the two, 10,000mAh is more versatile. It can charge your device more than once and gives better backup during the day. A 5,000mAh power bank is for very light use only like quick top-ups or emergencies.

How long will a 5000mAh charger last?

A 5,000mAh power bank can usually give one full charge to a smartphone. If your device has a large battery, it may not charge it completely. It’s best for short trips or emergency use, not for extended time away from outlets.