Electric Charge Converter

Electric charge is one of the most fundamental quantities in physics and electrical engineering. It represents the physical property of matter that causes it to experience a force when placed in an electromagnetic field. The movement of electric charge constitutes electric current, and the storage of charge underpins capacitor and battery technology. Understanding charge units and their conversions is essential for anyone working with batteries, capacitors, electrochemistry, or electrical systems. This electric charge converter provides instant, accurate conversions between all commonly used charge measurement units.

The Coulomb: The SI Unit of Charge

The Coulomb (C) is the SI unit of electric charge, named after French physicist Charles-Augustin de Coulomb. One Coulomb equals the charge transported by a current of one Ampere in one second. In terms of elementary particles, one Coulomb contains approximately 6.242 × 10¹⁸ electrons (or the equivalent in protons). A typical lightning bolt transfers about 15-350 Coulombs of charge. In everyday electronics, microcoulombs (µC) and nanocoulombs (nC) are more practical units for describing static electricity and small capacitor charges.

Ampere-Hours: The Battery Capacity Standard

The ampere-hour (Ah) is the most practical unit for measuring battery capacity. One ampere-hour equals 3,600 Coulombs - the charge delivered by one Ampere flowing for one hour. Car batteries are typically rated at 40-100 Ah, meaning they can theoretically supply 40-100 Amperes for one hour, or proportionally less current for longer periods. Deep-cycle batteries for solar systems might have capacities of 100-400 Ah. Industrial and electric vehicle batteries reach thousands of ampere-hours. Understanding this unit helps estimate battery runtime and compare different battery options.

Milliampere-Hours: Small Battery Standard

Milliampere-hours (mAh) is the standard unit for smartphone batteries, power banks, and small electronic device batteries. One mAh equals one-thousandth of an Ah, or 3.6 Coulombs. Modern smartphones typically have batteries rated 3,000-5,000 mAh. AA alkaline batteries hold approximately 2,500-3,000 mAh. Power banks may range from 5,000 mAh (pocket-sized) to 26,800 mAh (laptop-charging capable). When comparing devices, mAh ratings help estimate relative battery life, though actual runtime depends on voltage and power consumption patterns.

Practical Relationships and Calculations

The relationship between charge, current, and time is fundamental: Charge (C) = Current (A) × Time (s). This means a 5,000 mAh battery discharging at 500 mA will last approximately 10 hours (under ideal conditions). When a capacitor stores charge, the relationship is Q = C × V, where Q is charge in Coulombs, C is capacitance in Farads, and V is voltage. A 1,000 µF capacitor charged to 50V holds 0.05 Coulombs (50,000 µC). These calculations are essential for designing power systems and predicting device runtime.

Electric Charge Conversion Reference

• 1 Coulomb (C) = 1 Ampere-second = 1/3,600 Ah ≈ 0.278 mAh
• 1 Ampere-hour (Ah) = 3,600 C = 1,000 mAh
• 1 Milliampere-hour (mAh) = 3.6 C = 0.001 Ah
• 1 Elementary charge (e) = 1.602 × 10⁻¹⁹ C
• 1 Microcoulomb (µC) = 10⁻⁶ C = 0.000278 mAh

Practical Applications

• Battery Selection: Comparing battery capacities across different specifications
• Runtime Estimation: Calculating how long a battery will power a device
• Charging Time: Determining required charging time based on charger current
• Capacitor Sizing: Calculating stored charge for backup power applications
• Electrochemistry: Computing charge transfer in electroplating and electrolysis
• Power Management: Designing battery management systems for electronics