60
C
30
s
60,000,000
µC
16.666667
mAh
3.7449e+20
60
J
60
C
30
s
60,000,000
µC
16.666667
mAh
3.7449e+20
60
J
The Charge Calculator determines the total electric charge that flows through a conductor given the current and time. Electric charge is one of the most fundamental quantities in physics—it is the property of matter that causes it to experience electromagnetic forces. This calculator uses the defining relationship between current, charge, and time to compute results in multiple units and also tells you exactly how many electrons correspond to that charge.
Electric current is defined as the rate of flow of electric charge. When a steady current \(I\) flows for a time \(t\), the total charge transferred is:
$$Q = I \cdot t$$
The SI unit of charge is the coulomb (C), named after Charles-Augustin de Coulomb. One coulomb equals the charge transported by a current of one ampere flowing for one second. In practical terms, one coulomb is an enormous number of elementary charges—approximately \(6.242 \times 10^{18}\) electrons.
The elementary charge \(e = 1.602176634 \times 10^{-19}\) C is a fundamental physical constant defined exactly by the 2019 SI redefinition. Every electron carries a charge of \(-e\), and every proton carries \(+e\). The number of electrons that flow through a wire is therefore \(n = Q / e\).
Charge calculations are essential across many domains. Battery engineers use milliampere-hours (mAh) to specify battery capacity—a 3000 mAh battery can deliver 3000 mA for one hour, or equivalently, 3 coulombs per second for 3600 seconds, totaling 10,800 coulombs. Electrochemists use Faraday's laws of electrolysis, which relate the charge passed through an electrolyte to the mass of material deposited. Semiconductor physicists track charge carriers (electrons and holes) to design transistors and integrated circuits.
This calculator accepts current in amperes and time in seconds, minutes, or hours. It outputs the charge in coulombs, microcoulombs, and milliampere-hours, along with the number of electrons and the energy that charge would carry at a potential of 1 volt. Whether you are calculating battery runtime, designing an electroplating process, or solving a physics homework problem, this tool delivers precise results instantly.
The calculator applies the fundamental definition of electric current:
$$Q = I \cdot t$$
where \(Q\) is charge in coulombs (C), \(I\) is current in amperes (A), and \(t\) is time in seconds (s).
If time is entered in minutes or hours, it is first converted to seconds: \(t_{\text{sec}} = t_{\text{min}} \times 60\) or \(t_{\text{sec}} = t_{\text{hr}} \times 3600\).
Number of electrons:
$$n = \frac{Q}{e} = \frac{Q}{1.602176634 \times 10^{-19}}$$
Milliampere-hours:
$$Q_{\text{mAh}} = I_{\text{mA}} \times t_{\text{hours}} = (I \times 1000) \times \frac{t_{\text{sec}}}{3600}$$
Energy at 1 V reference:
$$E = Q \cdot V = Q \cdot 1 = Q \text{ joules}$$
This gives a sense of energy scale—multiply by the actual voltage for real energy values.
The charge in coulombs tells you the total amount of charge transferred. The electron count shows the staggeringly large number of charge carriers involved even in small currents. The mAh value is directly comparable to battery capacity ratings. For reference, a typical AA battery has about 2500 mAh capacity, a smartphone battery is 3000–5000 mAh, and an electric car battery can be 50,000–100,000 mAh (50–100 Ah).
Inputs
Results
A USB-C charger delivering 2 A for 30 minutes transfers 3600 C of charge, equivalent to 1000 mAh. About 2.25 × 10²² electrons flow through the cable.
Inputs
Results
A sensor drawing 5 mA for 10 seconds transfers 0.05 C—a modest 50,000 µC, yet this still involves over 3 × 10¹⁷ electrons.
One ampere-hour (Ah) equals 3600 coulombs, because 1 A flowing for 1 hour (3600 seconds) transfers 3600 C. Therefore, 1 mAh = 3.6 C. Battery capacity in mAh tells you the total charge the battery can deliver before it is depleted.
One coulomb contains approximately \(6.242 \times 10^{18}\) electrons. This is the reciprocal of the elementary charge: \(1/e = 1 / 1.602176634 \times 10^{-19} \approx 6.242 \times 10^{18}\). Even a tiny current of 1 µA involves about 6.2 trillion electrons per second.
In physics, we assign negative charge to electrons and positive charge to protons. However, conventional current direction is defined as the flow of positive charge. This calculator computes the magnitude of charge (always positive) based on current magnitude and time. The sign convention depends on your circuit analysis framework.
The elementary charge \(e = 1.602176634 \times 10^{-19}\) C is the magnitude of charge carried by a single proton (or electron). Since the 2019 SI redefinition, it is an exact defined constant. It is fundamental because all observable charges in nature are integer multiples of \(e\)—charge is quantized.
The energy carried by a charge depends on the electric potential (voltage) it moves through: \(E = QV\). One coulomb moving through one volt gains one joule of energy. This is why batteries are rated by both capacity (mAh) and voltage—the total energy is the product of charge and voltage.
Faraday's constant \(F = N_A \cdot e \approx 96485\) C/mol is the total charge carried by one mole of electrons. It is central to electrochemistry: the mass of substance deposited during electrolysis is proportional to the charge passed, divided by Faraday's constant and the substance's valence.
Roboculator Team
The Roboculator Team explains calculations, planning tools, and practical formulas in clear language for real-life situations.
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