Example 1
I = 2 A, t = 10 s → Q = 20 C.
Electric Charge Calculator
Type current I [A] and time t [s]. The calculator computes Q = I t: 2 A and 10 s is 20 C, and 1 A for 3600 s is 3600 C, one ampere-hour. Negative t will not run.
Inverse: I = Q/t. Power: P = U·I.
Result
Current I (A) and Time t (s). The result shows up here.
How it works
Charge from current and time is Q = I t. At 2 A and 10 s you get 20 C. At 0.5 A and 120 s you get 60 C. At 1 A and one hour (3600 s) you get 3600 C, or 1 Ah. 1 Ah = 3600 C. The t field does not take “1” as an hour.
The form has two fields: I in amperes and t in seconds. The result is in coulombs. A minute is 60, an hour is 3600. A comma and a period mean the same I: 0,5 and 0.5.
t cannot be negative: time does not run backward in this calculator. Typed 0 in I or t gives Q = 0. Both fields need a number before 20 C appears. A negative I is current direction, not a seconds mix-up.
I = Q/t is on the neighbouring page: same pair, you solve for current. C = Q/U is capacitor capacitance, not charge from current. P = U I is next door and does not count coulombs.
The calculator uses steady I and t. When current jumps, that is an integral, not this product. Type 1 Ah as 3600 s at 1 A, not as 1 in the t field.
Type 2 and 10, click Calculate, and check 20 C. Treat 3600 C at 1 A and 3600 s as 1 Ah, not as one hour typed in t.
How to use
- In the first field enter I in amperes, for example 2.
- In the second field enter t in seconds, for example 10. One hour is 3600, not 1.
- Click Calculate. The calculator multiplies I by t. 2 A and 10 s give 20 C. 1 A and 3600 s give 3600 C, or 1 Ah.
- t cannot be negative. Typed 0 gives Q = 0. Both fields need a number.
- For I = Q/t, open current I = Q/t. Capacitance C = Q/U is a different page.
Formula
Q = I · t
SI units: C, A, s. Time t cannot be negative.
Q, I, and t on the charge card
Charge from current and time: Q = I·t. 2 A and 10 s is 20 C. 1 A for 3600 s is 3600 C, one ampere-hour.
- Q
- Charge [C]. 2 × 10 = 20 C. Not capacitance C = Q/U.
- I
- Current [A]. Steady I over t. 1 A for an hour is 3600 C.
- t
- Time [s]. Negative values are rejected. An hour is 3600, not 1 h in the field.
Real-life examples
Example 2
Small current, longer time: Q = 60 C.
Example 3
1 Ah: Q = 3600 C.
Example 4
I = 3 A, t = 5 s → Q = 15 C.
Example 5
LED: I = 20 mA, t = 500 s → Q = 10 C.
Example 6
Short pulse of high current.
Example 7
Q = 6 C.
Example 8
12 min at 5 A → Q = 3600 C.
Example 9
Half an hour: Q = 3600 C (1 Ah).
Example 10
2 h charging: Q = 3600 C.
Ways to use this calculator
- You compute 20 C from 2 A for 10 s.
- You check 1 Ah: 1 A for 3600 s = 3600 C.
Frequently asked questions
How much Q at 2 A and 10 s?
Charge is 20 C. That is the product 2 × 10. Steady current for ten seconds, not capacitance C = Q/U.
How much at 1 A and 3600 s?
You get 3600 C. That is one ampere-hour: 1 A for an hour, and an hour is 3600 s.
Which units do I type?
Current I [A], time t [s]. Result Q [C]. 1 Ah = 3600 C, so type an hour as 3600, not as 1.
Do I type 1 for 1 Ah?
No. Field t wants t [s]. 1 h = 3600 s, then Q = 3600 C at 1 A. A 1 in t gives only 1 C.
How is this different from I = Q/t?
Here you solve charge from current and time. There you divide Q by t and get I. Same pair, different unknown.
Does a comma in 0.5 A work?
Yes. 0.5 and 0,5 are the same I [A]. 0.5 A for 120 s is 60 C.
Where is C = Q/U?
On the capacitance page. There C [F] from charge and voltage. Here Q comes from I and t, with no volts.
Can t be negative?
No. Time running backward is rejected. Zero seconds gives Q = 0 C, because nothing has flowed yet.
How much at 0.5 A and 120 s?
Charge is 60 C. Half an ampere for two minutes is 0.5 × 120.
Where is P = U I?
On the electric-power page. There watts from volts and amperes. Here only charge, no power.
Knowledge sources
The formula is the school one. Units follow SI; NIST SP 330 and BIPM define the measures, not your result.
Page updated in 2026.