Ohms to Siemens Converter
A 50 ohm resistor has a conductance of 0.02 siemens, which is 20 millisiemens.
Quick answer: Divide 1 by the resistance in ohms. For example, 50 ohms is 0.02 S, 5 ohms is 0.2 S and 200 ohms is 0.005 S.
The ohms to siemens formula
Siemens equal one divided by ohms.
The siemens is the unit of conductance, the reciprocal of resistance.
Take 50 ohms. 1 ÷ 50 gives 0.02 S.
Take 5 ohms. 1 ÷ 5 gives 0.2 S.
Conductance and resistance
Conductance is the reciprocal of resistance, so one siemens equals one reciprocal ohm. A 5 ohm resistor has a conductance of 200 mS (Wikipedia: Siemens (unit)).
Resistance tells you how much a part holds back current. Conductance tells you how well it lets current through.
How to convert ohms to siemens step by step
- Read the resistance in ohms.
- Divide 1 by that number.
- The answer is in siemens.
- Multiply by 1,000 if you need millisiemens.
Example 1: 50 ohms
- Start with 50 ohms.
- 1 ÷ 50 = 0.02.
- The conductance is 0.02 S.
50 ohms = 0.02 S
Example 2: 5 ohms
- Start with 5 ohms.
- 1 ÷ 5 = 0.2.
- The conductance is 0.2 S.
5 ohms = 0.2 S
Example 3: 200 ohms
- Start with 200 ohms.
- 1 ÷ 200 = 0.005.
- The conductance is 0.005 S.
200 ohms = 0.005 S
The three examples below use common sizes.
Each one shows the sum in full.
ohms to siemens conversion table
| Resistance | Conductance (S) | Conductance (mS) |
|---|---|---|
| 1 ohms | 1 S | 1,000 mS |
| 2 ohms | 0.5 S | 500 mS |
| 4.7 ohms | 0.2128 S | 212.77 mS |
| 10 ohms | 0.1 S | 100 mS |
| 22 ohms | 0.0455 S | 45.455 mS |
| 50 ohms | 0.02 S | 20 mS |
| 100 ohms | 0.01 S | 10 mS |
| 220 ohms | 0.004545 S | 4.545 mS |
| 470 ohms | 0.002128 S | 2.128 mS |
| 1,000 ohms | 0.001 S | 1 mS |
| 4,700 ohms | 0.000213 S | 0.2128 mS |
| 10,000 ohms | 0.0001 S | 0.1 mS |
The highlighted row is the default of the calculator. The last column gives mS.
A quick mental shortcut for ohms to siemens
A quick guess is to divide 1 by the ohms in your head. So 10 ohms is 0.1 S and 100 ohms is 0.01 S.
Double the ohms and the siemens halve.
Siemens and the old name mho
The unit was once called the mho, which is ohm spelled backward. NIST treats that name as unaccepted and says to avoid it (Wikipedia: Siemens (unit)).
You still see it on older equipment.
Conductances add in parallel
When parts share the same voltage, their conductances add. A 0.02 S part and a 0.05 S part together give 0.07 S.
That is why conductance is handy for parallel circuits.
Zero and very large resistance
As the resistance grows, the conductance shrinks toward zero. An open circuit has almost no conductance.
Zero ohms would mean unlimited conductance, so the formula cannot be used with zero.
Quick conversion answers
| Conversion | Result |
|---|---|
| 10 ohms | 0.1 S |
| 50 ohms | 0.02 S |
| 100 ohms | 0.01 S |
| 1,000 ohms | 0.001 S |
Where this conversion is used
Electronics students switch between resistance and conductance in circuit problems.
Technicians read conductance values on meter and sensor data sheets.
Common mistakes to avoid
- Dividing the wrong way. Siemens equals 1 divided by ohms, not ohms divided by 1.
- Using zero ohms. The conductance would be endless, so the formula fails.
- Mixing S and mS. One siemens is 1,000 millisiemens.
- Mixing conductance with conductivity. Conductivity is a material property in S/m.
Related converters
- K to ohms
- conductivity to resistance
- ohms to kilowatts
- conductivity to resistivity
- Ohms to Temperature
More resistance values
0.5 ohms is 2 S. 3 ohms is 0.3333 S. 8 ohms is 0.125 S.
15 ohms is 0.06667 S. 33 ohms is 0.0303 S. 75 ohms is 0.01333 S.
150 ohms is 0.006667 S. 330 ohms is 0.00303 S. 2,200 ohms is 0.0004545 S.
Doubling the first number
1 ohms is 1 S. 6 ohms is 0.1667 S. 16 ohms is 0.0625 S.
30 ohms is 0.03333 S. 66 ohms is 0.01515 S. 150 ohms is 0.006667 S.
300 ohms is 0.003333 S. 660 ohms is 0.001515 S. 4,400 ohms is 0.0002273 S.
Common resistor values as conductance
10 ohms is 0.1 S. 47 ohms is 0.02128 S. 100 ohms is 0.01 S.
220 ohms is 0.004545 S. 1,000 ohms is 0.001 S.
More worked examples
A 4.7 ohm resistor has a conductance of about 0.2128 S. A 22 ohm resistor has about 0.04545 S, which is 45.45 mS.
A 470 ohm resistor has about 0.002128 S, which is 2.128 mS. A 1,000 ohm resistor has exactly 0.001 S, which is 1 mS.
Going from siemens to ohms
The step works both ways. Divide 1 by the siemens to get ohms.
So 0.2 S is 5 ohms and 0.05 S is 20 ohms. A conductance of 2.5 mS is 0.0025 S, which is 400 ohms.
A parallel example
Two 100 ohm resistors sit side by side on the same supply. Each has a conductance of 0.01 S, so together they have 0.02 S.
Turn that back with 1 divided by 0.02, and the pair acts like one 50 ohm resistor.
Checking your answer
Multiply the siemens by the original ohms. The product must be 1.
For 50 ohms and 0.02 S, 0.02 times 50 is 1, so the answer is right.
What the answer tells you
A larger conductance means the part lets more current through for the same voltage. One siemens passes one extra ampere for each extra volt (Wikipedia: Siemens (unit)).
So a 10 ohm part, at 0.1 S, passes 0.1 A for each volt across it.
A 100 ohm part, at 0.01 S, passes only 0.01 A for each volt.
Frequently asked questions
How do I convert ohms to siemens?
Divide 1 by the resistance in ohms.
How many siemens is 10 ohms?
10 ohms is 0.1 siemens, or 100 mS.
What is a mho?
It is an old name for the siemens. It is ohm spelled backward.
How many mS is 1 S?
1 S is 1,000 mS.
Is conductance the same as conductivity?
No. Conductance belongs to one part. Conductivity is a property of a material, in S/m.
Can I use zero ohms?
No. You cannot divide by zero. A perfect short has unlimited conductance.
Sources
- Wikipedia: Siemens (unit) (en.wikipedia.org)
