How to Calculate Power Bank Watt Hours for TSA Approval
Updated 2026-08-25 · Power Bank Guide
When you’re planning a trip, one of the first questions is how to calculate power bank watt hours for TSA and stay within the 100‑Wh limit. Knowing the math and the real‑world charge counts helps you pick the right size for your phone or tablet, and ensures you can bring it aboard without a hassle.
1. The TSA 100‑Wh Rule Explained
The Transportation Security Administration (TSA) allows power banks with a capacity up to 100 Wh in carry‑on luggage. The rule applies to both 2000‑mAh and 20000‑mAh batteries. Airlines may have stricter limits, so always double‑check before you fly.
2. Converting mAh to Watt‑Hours
The conversion is simple:
Wh = (mAh ÷ 1000) × 3.7 V
3.7 V is the nominal voltage of a single Li‑ion cell. For example, a 20000‑mAh pack is:
Wh = (20000 ÷ 1000) × 3.7 ≈ 74 Wh
74 Wh is well below the 100‑Wh ceiling, making it flight‑safe.
3. How Many Charges Can You Expect?
Real‑world efficiency is usually 60–70 %. To estimate the number of full charges for a typical phone, divide the power‑bank Wh by the phone’s battery Wh:
- iPhone 17: ~12 Wh (3000 mAh). 74 Wh ÷ 12 Wh ≈ 6–7 full charges.
- Samsung Galaxy S24: ~15 Wh (4000 mAh). 74 Wh ÷ 15 Wh ≈ 4–5 charges.
- Google Pixel 8: ~13 Wh (3500 mAh). 74 Wh ÷ 13 Wh ≈ 5–6 charges.
- Android tablets (~30 Wh): 74 Wh ÷ 30 Wh ≈ 2–3 charges.
These numbers assume a 60‑70 % efficiency and a fresh, fully charged power bank.
4. USB‑C Power Delivery and the 22.5 W Slot
USB‑C PD is the most common fast‑charging standard today. A 22.5 W output (5 V × 4.5 A) can fully charge most modern smartphones in about 30–40 minutes. It’s also safe for tablets and some laptops that support 20 W or 30 W input.
When buying a travel power bank, look for:
- USB‑C PD 22.5 W or higher
- At least one USB‑A port for older devices
- Built‑in cable or a detachable USB‑C cable (for better durability)
- Indicators for remaining Wh or mAh
5. Choosing the Right Capacity for Your Trips
Capacity decisions boil down to:
- Trip length and device usage: Longer flights or multi‑day trips need more capacity.
- Number of devices: If you carry a phone, tablet, and a smartwatch, aim for 20000 mAh or more.
- Weight and size: 20000 mAh packs weigh ~200–250 g but are compact enough to fit in a pocket.
- Price vs. features: Higher capacity often comes with extra ports or better build quality.
Is 20000 mAh enough? For most travelers, yes. It offers 5–7 phone charges and a couple of tablet charges, keeping you powered through a day or two without a wall outlet.
6. The INIU 20000 mAh Portable Charger – A Flight‑Safe Choice
The INU 20000 mAh Portable Charger (Flight‑Safe) delivers 22.5 W fast charging, is TSA compliant, and includes a USB‑C cable and flashlight. It can charge an iPhone 17, Samsung, Xiaomi, or Google phone multiple times, making it a solid pick for travelers who need reliability and portability. Its compact size and flight‑safe rating mean you can pack it in your carry‑on with confidence.
FAQ
What is the maximum Wh I can carry on a plane?
Most airlines allow up to 100 Wh for carry‑on power banks. Some carriers have lower limits (e.g., 80 Wh), so check your airline’s policy before you travel.
How does efficiency affect the number of charges?
Efficiency accounts for power loss during conversion and delivery. A typical 60–70 % efficiency means you’ll get slightly fewer full charges than the theoretical Wh calculation suggests.
Can I use a power bank with a higher voltage than my device requires?
No. Devices rely on their own power‑management circuits. Using a higher voltage can damage the device. Stick to the USB‑C PD specs your phone supports (e.g., 5 V × 4.5 A for 22.5 W).