What Size Power Bank Do I Need? Equipment and Scene

Generally, a 5,000mAh magnetic pack is perfect for light commuting; 10,000mAh is the "Goldilocks" standard for heavy all-day use; and a 20,000mAh+ brick (with 45W output) is mandatory if you need to power a laptop or go off-grid. However, there is more to it than just the numbers on the box. Factors like wattage, airline restrictions, and charging speed matter just as much as capacity.

In this guide, we will break down exactly how to pick the right one for your specific devices and scenarios.

Choose Based on Your Devices

Not all power banks are created equal. The most common mistake is buying a battery based solely on capacity (mAh) without considering output power (Wattage). Different devices require different charging speeds and energy reserves.

1. Mobile Phones

This is the primary use case for most people. Modern smartphones (iPhone, Samsung, Android) typically have battery capacities between 3,500mAh and 8,000mAh.

• The Solution:

• 5,000mAh: Suitable for one full charge. This is best for daily commuting or emergency backup.

• 10,000mAh: The recommended standard. It provides approximately 1.5 to 2 full charges, making it ideal for heavy users or overnight trips where you might miss a wall outlet.

2. Apple Watch & Wireless Earbuds

• Capacity Requirement: 5,000mAh – 10,000mAh.

• 5,000mAh (Minimum): Ideal if you prioritize portability. It provides enough buffer to give your phone a healthy boost while keeping your accessories alive.

• 10,000mAh (Recommended): This is a more reliable option. It can fully charge your phone, and as a versatile power bank for Apple Watch, it gives you peace of mind all day long.

• What to Look For:

• Trickle Charge Mode: This is crucial. Wearables draw so little power that standard banks often turn off automatically. Ensure your bank has a "Low Current Mode" to keep the power flowing.

• Ideally, a mobile charger 3 in 1: While not absolutely necessary, it functions as a portable charger with a built-in magnetic charging dock, allowing you to charge your phone, watch, and earphones simultaneously. This way, you can charge all your devices at once without carrying around a mess of cables.

3. Tablets (iPads / Android Tablets)

Tablets have massive internal batteries, typically ranging from 7,000mAh (like an iPad Air) to over 10,000mAh (like an iPad Pro). This is double or triple the size of a standard smartphone battery.

The Recommendation: Minimum 10,000mAh.

• 10,000mAh: This is the baseline. It is generally sufficient to provide one full charge for most standard tablets, which is perfect for a day out.

• 20,000mAh – 25,000mAh: If you want to be safe, go bigger. A capacity in this range ensures you have plenty of power reserves to keep a large-screen tablet running for a long flight, or to charge it fully with juice left over for your phone.

4. Laptops

Many people assume that since their laptop has a USB-C port, any USB-C power bank will work. This is a common misconception. Laptops require significantly higher wattage than phones. A standard phone power bank usually outputs 10W–15W. If you plug this into a laptop, the laptop will likely ignore it, or the battery will continue to drain even while plugged in.

The Solution: You need a power bank that specifically supports Power Delivery (PD).

• Wattage: Look for 45W as a minimum for thin ultrabooks, but 65W is the ideal standard to charge most laptops at full speed.

• Capacity: Because laptop batteries are large, you need at least 20,000mAh to provide a meaningful backup charge.

Choose Based on Your Scenario

Besides technical specifications, portability and usability are also crucial factors. If the battery is too heavy and difficult to carry, then even a large capacity is meaningless. We need to choose the right portable charger based on your actual lifestyle.

1. The Daily Commute

• The Pick: 5,000mAh MagSafe Pack or a 3-in-1 Charging Stand.

• For the subway ride, a magnetic pack is the most convenient safety net—no cables required. Alternatively, keeping a 3-in-1 MagSafe Stand on your office desk allows you to top up your phone, watch, and buds while you work, often eliminating the need to carry a power bank entirely.

2. Travel & Sightseeing

• The Pick: 10,000mAh Magsafe.

• This is the ideal balance between power and portability. It's smaller and lighter than a standard smartphone, easily fitting into a pocket or small bag. It provides enough power to keep the phone running even under heavy load, without being as bulky as a brick.

3. Camping / Group Travel

• The Pick: 20,000mAh – 25,000mAh.

• In this case, capacity is more important than weight. You'll need a high-capacity usb c power bank to provide central power for all your equipment. If you frequently engage in outdoor activities, choose a model with a rugged or waterproof casing.

4. Working Outside

• The Pick: 20,000mAh+ with 65W PD.

• As mentioned earlier, standard chargers won't work here. A high-wattage (65W) bank effectively doubles your laptop's battery life, giving you the freedom to work from anywhere without anxiety.

The Cheat Sheet

Too lazy to read my ramblings above? I get it. Here is the summary. Find your "Persona" in the left column and buy the size on the right.

portable charger Specification

After determining the capacity, you should also check the following three technical specifications before purchasing. These characteristics determine the compatibility and ease of use of the power bank.

1. Input Speed (Recharge Time)

Most people focus on how fast a power bank charges their phone, but they forget to check how fast the power bank charges itself.

• The Issue: A high-capacity battery (like 20,000mAh) can take 15 to 20 hours to refill if it uses a slow, older standard input (10W).

• The Fix: Look for "PD Input" (18W, 30W, or higher). This feature allows the battery to accept a fast charge, cutting the refill time down to just a few hours.

2. Port Versatility

Ensure the portable charger uses modern standards to minimize the number of cables you need to carry.

• The Fix: Look for "USB-C Bidirectional" ports. This means the same USB-C port can be used for both output (charging your phone) and input (charging the battery). This allows you to use a single cable for everything. Avoid models that still rely on Micro-USB for input.

3. Pass-Through Charging

This is a specific feature that is incredibly useful for travelers with limited wall outlets.

• The Benefit: The plug in power bank can be plugged into a wall outlet, and then your phone can be plugged into the power bank. The intelligent circuitry first charges your phone and then fully charges the battery pack, so you wake up with both devices fully charged, using only one wall outlet. It can also charge your phone when no charger is available.

Common Mistakes to Avoid

1. Airline Restrictions

Flying with batteries requires strict adherence to safety regulations. First, never put a portable charger in checked luggage; it must go in your carry-on.

Second, check the capacity limits :

• Under 100Wh (approx. 20,000mAh): Allowed without special permission.

• 100Wh – 160Wh: Requires airline approval, and you are typically limited to 2 units per person.

• Over 160Wh: Strictly prohibited on passenger planes.

2. The "Efficiency" Reality

Marketing boxes often list the theoretical capacity, but real-world performance is different.

• The Reality: Due to voltage conversion and heat loss, power banks are typically only 70% to 75% efficient.

• The Math: A 10,000mAh power bank will not deliver exactly 10,000mAh to your device. It will deliver roughly 7,500mAh. Always buy a slightly larger capacity than you think you need to account for this loss.

3. The Cable Quality

A high-end power bank cannot deliver fast speeds through a low-quality cable.

• The cable acts as the pipeline. If you use an old or cheap cable, it may throttle the charging speed to protect the device. To get the 45W or 65W speeds you paid for, ensure you are using a certified cable capable of handling that wattage.

4. Overbuying Capacity

Unless you're going on a wilderness expedition or need to charge your laptop or tablet, don't blindly buy bulky power banks.

• The Sweet Spot: For most people, 10,000mAh is the perfect balance of size and power. Alternatively, if you just need a daily safety net, a 5,000mAh wireless pack offers the most comfortable, cable-free experience for a quick top-up.