Case 1
- Inductance L (H)
- 2H
- Current I (A)
- 3A
9.000000J
Open with these valuesInductor Energy Calculator
9.000000J
Result: 9.000000 JHalf the inductance times the current squared gives joules: a 2 H coil carrying 3 A holds 9 J. The current is squared, so its direction does not matter and doubling it quadruples the energy. Enter henries, not millihenries: a 5 mH choke is 0.005 H.
The numbers at a glance
Held fixed: Inductance L (H) 2.000000000000 H.
| Current I (A) (A) | Result (J) |
|---|---|
| 0.000 | 0.000000 |
| 1.000 | 1.000000 |
| 2.000 | 4.000000 |
| 3.000Your value | 9.000000 |
| 4.000 | 16.000000 |
| 5.000 | 25.000000 |
| 6.000 | 36.000000 |
Worked examples
Case 2
- Inductance L (H)
- 0.5H
- Current I (A)
- 4A
4.000000J
Open with these valuesCase 3
- Inductance L (H)
- 0.001H
- Current I (A)
- 10A
0.050000J
Open with these valuesHow it's calculated
E = ½ × L × I²
- StepEnter the inductance in henries — a 5 mH choke is 0.005 H.
- StepEnter the current flowing through the coil in amperes.
- ResultRead the stored energy in joules; one joule is one watt-second.
Reference table
| L (H), I (A) | What it is | Energy (J) |
|---|---|---|
| 0.001, 10 | 1 mH choke at 10 A | 0.05 |
| 1, 1 | 1 H coil at 1 A | 0.5 |
| 10, 0.5 | 10 H coil at 0.5 A | 1.25 |
| 0.5, 4 | 0.5 H coil at 4 A | 4 |
| 2, 3 | 2 H coil at 3 A | 9 |
| 2, -3 | same coil, current reversed | 9 |
Questions
How do I calculate the energy stored in an inductor?
Multiply half the inductance by the current squared: E = ½ × L × I². Use henries and amperes and the answer comes out in joules. A 2 H coil carrying 3 A stores 9 J.
Where is the energy in an inductor stored?
In the magnetic field the current creates around the coil. As long as current keeps flowing, the field and its energy persist. The inductor pushes that energy back into the circuit when the current tries to fall.
Why does doubling the current quadruple the stored energy?
Because the current is squared in the formula. Doubling it multiplies the energy by four and tripling it by nine. The inductance enters only to the first power, so it scales the energy in direct proportion.
Does a negative current give a negative energy?
No. The current is squared, so a reversed current stores exactly the same energy as its positive counterpart. A 2 H coil stores 9 J at 3 A and 9 J at minus 3 A.
Which units should I enter?
Henries for inductance and amperes for current, which gives joules. A coil rated in millihenries has to be divided by 1000 first, so 5 mH becomes 0.005 H. One joule equals one watt-second.
Sources and last check
Information, not professional advice.