Mah to Watt Calculator

mAh to Watt-Hour (Wh) Calculator

Total Energy Capacity:

0 Wh

function calculateWh() { var mah = document.getElementById("battery_mah").value; var voltage = document.getElementById("battery_voltage").value; var resultArea = document.getElementById("result_area"); var whResult = document.getElementById("wh_result"); var detail = document.getElementById("calculation_detail"); if (mah > 0 && voltage > 0) { // Formula: Wh = (mAh * V) / 1000 var wh = (mah * voltage) / 1000; whResult.innerHTML = wh.toFixed(2) + " Wh"; detail.innerHTML = "(" + mah + " mAh × " + voltage + " V) / 1000 = " + wh.toFixed(2) + " Wh"; resultArea.style.display = "block"; } else { alert("Please enter valid positive numbers for both capacity and voltage."); resultArea.style.display = "none"; } }

How to Convert mAh to Watt-Hours (Wh)

Understanding the relationship between milliampere-hours (mAh) and Watt-hours (Wh) is essential for comparing battery capacities across different devices like smartphones, laptops, and drones. While mAh measures electric charge, Wh measures total energy capacity.

The Conversion Formula

Watt-Hours (Wh) = (Capacity (mAh) × Voltage (V)) / 1,000

Why Voltage Matters

A common mistake is comparing batteries based on mAh alone. For example, a 10,000 mAh power bank at 3.7V holds significantly less energy than a 10,000 mAh laptop battery running at 14.8V. By converting to Watt-hours, you can compare the actual "fuel tank" size of different energy storage systems regardless of their operating voltage.

Practical Conversion Examples

• Standard Smartphone: 4,000 mAh at 3.8V
  Calculation: (4,000 × 3.8) / 1,000 = 15.2 Wh
• Power Bank: 20,000 mAh at 3.7V
  Calculation: (20,000 × 3.7) / 1,000 = 74 Wh
• Drone Battery (4S LiPo): 1,500 mAh at 14.8V
  Calculation: (1,500 × 14.8) / 1,000 = 22.2 Wh

Airline Travel & mAh Limits

Most international aviation authorities (like the FAA and TSA) limit portable lithium-ion batteries in carry-on luggage based on Watt-hours, not mAh. The standard limit is often 100 Wh per battery. If you have a large power bank, use this calculator to ensure it falls below the 100 Wh threshold to avoid confiscation at security checkpoints.

Frequently Asked Questions

Is mAh the same as Watts? No. mAh (milliampere-hour) is a unit of electric charge, while Watts (W) is a unit of power. Watt-hours (Wh) is the unit for energy capacity.

How do I find my battery voltage? This information is usually printed on the battery label itself, often listed as "Nominal Voltage." For standard Li-ion cells, this is typically 3.6V or 3.7V.