# Can't find the formula.

#### thedoc8

Joined Nov 28, 2012
148
I go to this site http://mustcalculate.com/electronics/capacitivereactance.php?f=60&r=500000

I can put in frequency in one box and reactance in another and it will spit out the value of the capacitor

Example 60Hz in one box and 500000 in the reactance and it will tell me 5. some odd nf.

I am looking for the formula that it is using to come up with the cap value from freq and reactance.

I thought I knew this till about half hour ago when I went to figure it out and now I just draw a blank and can't find the answer.

Thanks kindly

#### vu2nan

Joined Sep 11, 2014
162

#### SamR

Joined Mar 19, 2019
2,574
Xc = 1/6.28fC .: Xc(6.28fC) = 1 .: C = 1/Xc(6.28f)

Last edited:

#### thedoc8

Joined Nov 28, 2012
148

#### thedoc8

Joined Nov 28, 2012
148
Xc = 1/6.14fC .: Xc(6.14fC) = 1 .: C = 1/Xc(6.14f)
Thanks SamR that was it..! (c=1/Xc(6.15f) I see how I was screwing up now. Thanks

#### Papabravo

Joined Feb 24, 2006
14,410
Im looking for the value of the capacitor and that is the reactance of the capacitor. Thanks,
The units of reactance are ohms. For a capacitor the calculate reactance is valid for one frequency only. The units of capacitance are farads. The two units are related but are not the same thing. Don't know where you got 6.14 and 6.15, but the constant is 6.28 ≈ 2π

#### thedoc8

Joined Nov 28, 2012
148
Im looking for the value of the capacitor and that is the reactance of the capacitor. Thanks,
Second look it does work just got to swap the xc for c. Thanks

#### thedoc8

Joined Nov 28, 2012
148
The units of reactance are ohms. For a capacitor the calculate reactance is valid for one frequency only. The units of capacitance are farads. The two units are related but are not the same thing. Don't know where you got 6.14 and 6.15, but the constant is 6.28 ≈ 2π
Lol supposed to be 6.28,

• SamR

#### SamR

Joined Mar 19, 2019
2,574
I have my duh moment...

• cmartinez