Every electronic device you own has a tiny label that tells you exactly whether it will work safely abroad — but most travelers have never looked at it. That label, usually printed on the charger brick, power adapter, or bottom of the device, contains everything you need to know: the voltage it accepts, the current it draws, the frequency it expects, and its power consumption.
This guide walks through each field on a typical power label, explains what the numbers mean in plain English, and gives you a clear system for deciding whether each device needs just a plug adapter or a full voltage converter.
The video above covers the basics of international voltage differences. Below, we focus specifically on how to read the label on your own devices.
Figure 1: Anatomy of a typical device power label — each field and what it tells you about international compatibility
The INPUT Line: The Only Line That Matters
The INPUT line tells you what kind of electricity the device can safely accept from the wall. This is the line that determines whether your device works abroad. Here is what each part means:
| Field | Example | What It Means |
|---|---|---|
| V (Volts) | 100–240V | The range of voltages the device can accept. If this spans from ~100 to ~240, the device works on any wall outlet worldwide. |
| V (Volts) | 120V | The device only accepts US-standard voltage. Plugging it into a 220–240V outlet will damage it. |
| A (Amps) | 0.5A or 1.5A | The current the device draws. Multiply by voltage to get watts (W = V × A). This is useful for sizing a converter. |
| Hz (Hertz) | 50–60Hz | The frequency range accepted. 50–60Hz means it works in all countries. 60Hz only means it is designed for the US/Canada/Japan. |
| W (Watts) | 65W or 1875W | Total power consumption. This determines which converter size you need (the converter must be rated higher than the device wattage). |
| ~ (Tilde) | 100–240V~ | The tilde symbol means AC (alternating current). All wall outlets provide AC. |
| ⎓ or DC | OUTPUT: 5V ⎓ 3A | Direct current — this appears on the OUTPUT line and describes what the charger sends to your device. This is NOT the wall voltage. |
The OUTPUT Line: Why You Can Ignore It
The OUTPUT line on a charger tells you what voltage and current it sends to the device (e.g., OUTPUT: 5V 3A for a USB charger, or OUTPUT: 20V 3.25A for a laptop charger). This is not relevant to the question of international compatibility. The INPUT line is what matters — it tells you what the charger can accept from the wall.
A common mistake: seeing "OUTPUT: 5V" on a phone charger and thinking the charger operates at 5V. In reality, the charger accepts 100–240V from the wall (INPUT) and internally converts it to 5V (OUTPUT) for your phone. The charger itself is dual-voltage and works worldwide.
10 Common Devices: What Their Labels Actually Say
| Device | Typical INPUT Label | Wattage | Verdict |
|---|---|---|---|
| Apple iPhone charger (20W USB-C) | 100–240V ~ 50–60Hz, 0.5A | 20W | Adapter only |
| MacBook Pro charger (96W USB-C) | 100–240V ~ 50–60Hz, 1.5A | 96W | Adapter only |
| Canon battery charger (LP-E6) | 100–240V ~ 50–60Hz, 0.2A | 12W | Adapter only |
| Oral-B electric toothbrush charger | 100–240V ~ 50–60Hz | 1W | Adapter only |
| Nintendo Switch AC adapter | 100–240V ~ 50–60Hz, 1A | 39W | Adapter only |
| Conair 1875W hair dryer | 120V ~ 60Hz, 15.6A | 1875W | Converter required (2000W+) |
| CHI flat iron | 110–120V ~ 60Hz | 60W | Converter required |
| BaByliss Pro curling iron (dual-voltage model) | 110–240V ~ 50–60Hz | 45W | Adapter only |
| ResMed AirSense 11 CPAP | 100–240V ~ 50–60Hz, 1.0A | 90W | Adapter only (but check humidifier) |
| Keurig K-Cup coffee maker | 120V ~ 60Hz, 12A | 1440W | Do not bring — buy local |
For the complete list organized by device category, see our Which Devices Actually Need a Voltage Converter? guide.
Figure 2: Wattage comparison of common travel devices. Green = dual-voltage (adapter only). Red = single-voltage 120V (converter required). The dashed lines show DOACE converter capacity thresholds.
Three Possible Verdicts
After reading the label, every device falls into one of three categories:
Special Cases to Watch For
Devices with a voltage switch
Some older hair dryers and shavers have a tiny 120V/240V switch on the body. If your device has this switch, flip it to the correct voltage setting before plugging in. If you forget to switch it, the dual-voltage capability does not help — the device operates in whatever mode the switch is set to.
Devices with detachable power cords
Desktop computers, monitors, and some printers use a standard IEC C13 power cord. The device itself is typically 100–240V (check the label on the back of the device, not the cord). You can often simply buy or borrow a local power cord and plug it directly into the device — no adapter or converter needed.
CPAP machines
Most modern CPAP power supplies (including the ResMed AirSense 11 and Philips DreamStation 2) accept 100–240V. However, if you use a heated humidifier or heated tube, the total system draw increases. Also, CPAP machines with motors may benefit from a pure sine wave converter (DOACE LC-X35) for the cleanest power. See our CPAP Europe travel guide for full details.
Recommended DOACE Products
- For travelers whose devices are all dual-voltage (100–240V)
- 70W USB-C PD fast charging for laptops and phones
- Works in 200+ countries — compact GaN design
DOACE LC-C30 — 300W Voltage Converter
- For 120V devices under 300W (curling irons, flat irons, small appliances)
- Converts 220V → 110V with USB charging ports
DOACE C15 — 2000W Voltage Converter
- For high-wattage 120V devices (hair dryers up to 1875W, US electric kettles)
- 2000W capacity with fast-charging USB ports
Not sure which size you need? Our LC-C30 vs LC-X35 vs LC-X80 comparison and product pages include detailed wattage guides.
Frequently Asked Questions
What if the label is worn off or unreadable?
Search the exact model number online and look for the manufacturer's spec sheet. It will list the INPUT voltage. If you cannot find it, assume 120V only and bring a converter — it is safer than guessing wrong.
Does "100–240V" mean the device automatically adjusts?
Yes. Devices with this label have a switching power supply that automatically detects and adjusts to whatever voltage the outlet provides. You do not need to flip any switch — just plug it in through an adapter.
My hair tools say "dual voltage" but I cannot find a label. How do I verify?
Check the product manual or the manufacturer's website. Some "dual voltage" tools have a physical switch you need to flip between 120V and 240V mode. Others adjust automatically. If there is a switch, make sure to set it to the correct voltage before plugging in at your destination. For more on hair tools specifically, see our hair tools travel FAQ.
Does the frequency (Hz) on the label matter?
For most modern electronics (phones, laptops, tablets, cameras), no — they accept 50–60Hz automatically. Frequency matters for devices with AC motors (some fans, older turntables, clock radios) and timing-sensitive equipment. For a full explanation, see our 110V/220V/50Hz/60Hz guide.
What does the "CE" or "UL" marking on the label mean?
These are safety certifications. CE indicates the device meets European safety standards. UL indicates US/Canadian safety certification. FCC covers US electromagnetic interference standards. These markings do not directly tell you about voltage compatibility — you still need to check the INPUT line.
