Calculate current, time, or charge flow from any two values, with all unit conversions for A, mA, kA, s, min, h, C, mC, and kC units.

Charge Flow Calculator

Enter any 2 values to calculate the missing variable

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Charge Flow Formula

The charge flow calculator uses the relationship between electric charge, current, and time. In base SI units, charge flow is measured in coulombs, current is measured in amperes, and time is measured in seconds.

Q = I*t
I = Q / t
t = Q / I
  • Q = charge flow, in coulombs (C)
  • I = current, in amperes (A)
  • t = time, in seconds (s)

If you enter current and time, the calculator finds charge flow using Q = I*t. If you enter charge flow and time, it finds current using I = Q/t. If you enter charge flow and current, it finds time using t = Q/I.

The calculator converts milliamps, kiloamps, minutes, hours, millicoulombs, and kilocoulombs into base units before calculating. It then converts the result back to the unit you selected.

Common Charge, Current, and Time Units

Quantity Unit Symbol Conversion to base unit
Current milliampere mA 1 mA = 0.001 A
Current ampere A 1 A = 1 A
Current kiloampere kA 1 kA = 1000 A
Time minute min 1 min = 60 s
Time hour h 1 h = 3600 s
Charge flow millicoulomb mC 1 mC = 0.001 C
Charge flow kilocoulomb kC 1 kC = 1000 C

Charge Flow Reference Values

Current Time Charge flow
1 A 1 s 1 C
2 A 10 s 20 C
500 mA 60 s 30 C
0.25 A 1 h 900 C

Example Problems

Example 1: Find charge flow

You have a current of 3 A flowing for 20 s. Find the charge flow.

Q = I*t
Q = 3*20 = 60 C

The charge flow is 60 C.

Example 2: Find current

A charge flow of 240 C passes through a circuit in 2 minutes. Find the current.

First convert time to seconds:

2 min = 120 s

Then divide charge flow by time:

I = Q / t = 240 / 120 = 2 A

The current is 2 A.

FAQ

What is charge flow?

Charge flow is the amount of electric charge that passes a point in a circuit. It is measured in coulombs. A current of 1 ampere means 1 coulomb of charge flows each second.

What is the difference between current and charge flow?

Current is the rate of charge flow. Charge flow is the total amount of charge that has moved. For example, if 2 A flows for 5 s, the total charge flow is 10 C.

Why does time have to be converted to seconds?

The standard formula uses amperes, seconds, and coulombs. Since 1 ampere equals 1 coulomb per second, time must be in seconds before applying the formula. If you enter minutes or hours, the calculator converts them to seconds before calculating.