Wh (Watt-hour) vs. Ah (Amp-hour)
Note: This article is summarized from our team's daily technical support experience. We strive for accuracy and welcome your feedback or corrections.
Wh (Watt-hour) vs. Ah (Amp-hour)
When comparing battery specs for a portable power station, the distinction between Wh (Watt-hour) and Ah (Amp-hour) is critical.
While both measure capacity, they look at it from different angles.
1. The Fundamental Difference
-
Wh (Watt-hour): Measures Total Energy. It tells you exactly how much “work” the battery can do (e.g., how long it can power a lightbulb), regardless of its voltage.
-
Ah (Amp-hour): Measures Charge Capacity. It tells you how much electrical current the battery can deliver over time, but it doesn’t tell you the total energy unless you also know the voltage.
2. The Relationship Formula
The two are linked by Voltage (V).6 You can easily convert between them using these formulas:
3. Why Wh is the “True” Metric
In the world of portable power stations, Wh is much more useful than Ah because it allows for “apples-to-apples” comparisons.
Example Comparison:
Imagine you are looking at two batteries that both claim to be “100 Ah”:
-
Battery A (12V System): 100Ah*12V=1200Wh
-
Battery B (24V System): 100Ah*24V=2400Wh
Even though both are “100 Ah,” Battery B actually holds twice as much energy.9 This is why power station manufacturers (like Jackery, EcoFlow, or Bluetti) almost always lead with the Wh number (e.g., the “EcoFlow Delta 2” is roughly 1,024 Wh).
4. Practical Application: How long will my device last?
Using Wh makes math for your appliances very simple. You just divide the station’s Wh by your device’s Watts (W):
Summary Comparison Table
| Feature | Watt-hours (Wh) | Amp-hours (Ah) |
| What it measures | Total energy stored | Total charge capacity |
| Analogy | The total volume of gas in a tank | The amount of fuel flowing through a pipe |
| Best used for | Calculating runtime for appliances | Sizing wires and charge controllers |
| Uniformity | Universal (comparable across systems) | Context-dependent (depends on Voltage) |
Would you like me to help you calculate how long a specific power station would run your electronics?
Just let me know the Wh of the station and the wattage of your devices.
Amp Hours vs Watt Hours Made Simple
This video provides a very clear, visual explanation of why a 100Ah battery can have different energy levels depending on the voltage, helping you avoid common mistakes when sizing your power system.
