Electric Charge Calculator

Online calculator for the relationship between charge, current, and time

Calculation

Result
Charge:
Current:
Time:

Good to know

What is electric charge?

Electric charge is measured in coulombs (C) or ampere-seconds (As). It describes the relationship between current and time: \(1 \text{ C} = 1 \text{ As}\).

Important units
  • Charge \((Q)\): C, Ah (1 Ah = 3600 C)
  • Current \((I)\): A, mA, µA, kA, MA
  • Time \((t)\): s, min, h, days
Basic formula
\[Q = I \times t\]
Charge = Current × Time
Battery capacity

The storage capacity of a battery is specified as nominal charge in ampere-hours (Ah).

1 Ah = 3600 C

Formulas for electric charge

Electric charge is measured in coulombs (C) or ampere-seconds (As). \(1 \text{ C} = 1 \text{ As}\). In other words, the electric charge is \(+1 \text{ C}\) when there are \(6.248 \times 10^{18}\) more protons than electrons in and on a body, or \(-1 \text{ C}\) when there are \(6.248 \times 10^{18}\) more electrons than protons.

In practice, of course, the different numbers of protons and electrons in a body are not counted, but the current (amperes) is measured over a certain period of time. The measurement result can then be converted to ampere/seconds (As) or coulombs using the calculator above.

Electric charge

\[\text{Charge} = \text{Current} \times \text{Time}\] \[Q = I \times t\]

Unit: Coulomb (C) or ampere-seconds (As)

Electric current

\[I = \frac{Q}{t}\]

With time units:

\[I = \frac{\text{Ah}}{t[\text{h}]}\]

Time period

\[t = \frac{Q}{I}\]

With different units:

\[t[\text{h}] = \frac{\text{Ah}}{I}\]

Practical application

The storage capacity of a battery is called nominal charge, which is specified in ampere-hours (Ah). \(1 \text{ Ah} = 3600 \text{ C}\).

Example 1: Battery discharge

A battery with 2000 mAh is discharged with 500 mA:

\[t = \frac{2000 \text{ mAh}}{500 \text{ mA}} = 4 \text{ h}\]

The battery is discharged after 4 hours.

Example 2: Amount of charge

Current of 2 A flows for 3 hours:

\(Q = 2 \text{ A} \times 3 \text{ h} = 6 \text{ Ah}\)
\(Q = 6 \text{ Ah} = 21,600 \text{ C}\)

A charge of 6 Ah or 21,600 C flows.

Conversion factors
Charge units:
1 C = 1 As
1 Ah = 3,600 C
1 mAh = 3.6 C
1000 mAh = 1 Ah
Time units:
1 h = 60 min = 3,600 s
1 day = 24 h = 86,400 s
1 ms = 0.001 s
1 µs = 0.000001 s
Physical background

Electric charge is a fundamental property of matter. It arises from an imbalance between protons (positive charge) and electrons (negative charge) in a body. The smallest measurable charge is the elementary charge \(e = 1.602 \times 10^{-19} \text{ C}\).

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