In this article
COMPLEX builds a complex number like 3+4i from its real and imaginary parts, as text that the IM… functions understand. Used in AC circuits (impedance) and signal processing.
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Syntax
=COMPLEX(real_num, i_num, [suffix])| Argument | What it means |
|---|---|
real_num |
Real part |
i_num |
Imaginary part |
suffix |
“i” (default) or “j” (engineering) |
Examples
Example 1
=COMPLEX(A2,B2,"j")Result: 3+4j. See the worked example table below for more cases.
COMPLEX in practice
Where you will use it
- Impedance of a resistor plus inductor (R + jX)
- Phasors in AC circuits
- Teaching complex numbers
Worked example
| Real | Imag | Formula | Result |
|---|---|---|---|
| 3 | 4 | =COMPLEX(A2,B2,"j") | 3+4j |
| 10 | -5 | =COMPLEX(A3,B3,"j") | 10-5j |
| 0 | 1 | =COMPLEX(A4,B4,"j") | j |
Results calculated in Excel.
Mistakes people make
| Mistake | What to do instead |
|---|---|
| Typing 3+4i by hand with spaces | Write it without spaces: 3+4i |
| Mixing i and j | Use one suffix throughout a model |
Related functions
📚 Part of the free Excel course: Beginner → Expert · Try it in the Formula Lab or ask the AI Helper.
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