How to Calculate Power Bank Wh for TSA Flight Regulations

Updated 2026-08-25 · Power Bank Guide

When you’re packing for a trip, the first question is how to calculate power bank Wh for TSA to stay within the 100Wh carry‑on limit. A quick formula gives you the answer: Wh = (mAh ÷ 1000) × 3.7V. That 3.7V is the nominal cell voltage inside the battery. For a 20,000mAh pack, the math looks like this:

• 20,000 mAh ÷ 1,000 = 20 Ah
• 20 Ah × 3.7 V = 74 Wh

So a 20,000 mAh bank is well under the 100Wh threshold, making it TSA‑flight‑safe. It also means you can carry it in your carry‑on without extra paperwork.

What Devices Can a 22.5W USB‑C Bank Power?

USB‑C Power Delivery (PD) can deliver up to 100W in theory, but most portable chargers top out at 22.5W. That’s enough to keep a handful of gadgets alive while you’re on the move:

• Smartphones (iPhone, Samsung, Google) – 1–3 full charges depending on battery size.
• Tablets (iPad, Android tablets) – 1–2 full charges; iPads draw 10–20W.
• Gaming consoles (Nintendo Switch, Steam Deck) – 1 charge for Switch (7.5W), 1–2 for Steam Deck (up to 45W, but most use 22.5W).
• Cameras (Canon, Sony) – 1–2 charges; many DSLRs use 10–15W.
• Earbuds & smartwatches – 3–5 charges; these draw less than 5W.
• Laptops (USB‑C 45W‑80W models) – 1 charge for low‑power laptops (e.g., MacBook Air 45W). High‑power laptops (80W) may only get a partial top‑up.

Real‑world efficiency sits around 60–70%, so the 74Wh nominal rating translates to roughly 45–52Wh usable. That’s why a 20,000mAh bank can recharge an iPhone 17 about 5 times and a Samsung Galaxy S24 about 4 times.

How to Estimate Charge Counts for Your Gear

Use the device’s battery capacity (Wh) and the power bank’s usable Wh to estimate. Example: an iPhone 17 has ~20Wh. Divide 45Wh by 20Wh ≈ 2 full charges. Add a buffer for efficiency losses.

1. Find the device’s battery Wh (look up the model).
2. Divide the power bank’s usable Wh (≈45Wh) by that number.
3. Subtract 10–15% for real‑world losses.
4. Round down to the nearest whole charge.

For a 20,000mAh bank, a typical 10,000mAh phone (≈37Wh) gets about 1 charge. A 5,000mAh tablet (≈18Wh) can get 2–3 charges.

Choosing a Flight‑Safe Power Bank: The INIU 20000mAh Example

When you need a reliable, TSA‑approved option, the INU 20000mAh Portable Charger (Flight‑Safe) stands out. It delivers 22.5W fast charging, includes a USB‑C cable and a flashlight, and fits comfortably in a pocket or backpack. The 74Wh capacity keeps it under the 100Wh limit, and its 20,000mAh rating means you’ll get the charge counts mentioned above for most phones and tablets. The built‑in flashlight is a bonus for travelers who need a quick light source in dim situations.

USB‑C PD Wattage Explained

USB‑C PD is a flexible standard that negotiates voltage and current to match device needs. A 22.5W bank can output:

• 5V at 4.5A (22.5W)
• 9V at 2.5A (22.5W)
• 12V at 1.875A (22.5W)

Devices that support 5V/2A will still get a full charge, but at a slower pace. Laptops that need 45W or more will only see a partial top‑up from a 22.5W bank.

Practical Tips for TSA Compliance

1. Check the exact Wh rating. If you’re not sure, convert mAh to Wh using the formula above.

2. Verify airline policies. Some carriers have stricter rules about battery capacity.

3. Keep the bank in your carry‑on. Even if it’s under 100Wh, it’s best to avoid checked luggage.

4. Label the battery. Some airports still ask for a battery label or a small sticker with the Wh rating.

FAQ

What is the difference between mAh and Wh?

mAh measures charge capacity, while Wh accounts for both charge and voltage. Wh is the more accurate measure for airline limits.

Can I use a 100Wh power bank on a flight?

Yes, but you must declare it to the airline and it must be in your carry‑on. Always double‑check the airline’s latest policy.

Will a 22.5W charger fully charge my laptop?

It depends on the laptop’s power draw. For a 45W laptop it can give a full charge; for an 80W laptop it will only provide a partial top‑up.