Example 1
T = 39.24 N, N = 98.1 N → μ = 0.4.
Friction coefficient calculator
Type friction force T [N] and normal force N [N]. The calculator computes μ = T/N: 39 N and 98 N give 0.4. That is a number with no unit, not a force in newtons. Zero normal force does not divide.
T from a known μ: friction force. Sliding: incline with friction.
Result
Friction force T and Normal force N. The result shows up here.
How it works
The friction coefficient is μ = T/N. From a lab or a problem: T = 39.24 N and N = 98.1 N give μ = 0.4. 20 N on 400 N is μ = 0.05. 60 N on 200 N is 0.3. 15 N on 80 N is 0.1875. 8.49 N on 42.45 N is 0.2. 30 N on 250 N is 0.12. 40 N on 100 N is 0.4 again. 9000 N on 12,000 N is 0.75. The result has no unit. 0.4 is four tenths, not 0.4 N.
The form has two fields: T and N in newtons, or the labeled unit. The result is dimensionless. A comma and a period are the same T: 39,24 and 39.24. N must be greater than zero. Zero normal force does not divide. Typed 0 in T gives μ = 0: no friction at a positive N. Both fields need a number before 0.4 can appear.
The problem says whether that is μ_s or μ_k. The calculator computes one μ from T/N. It does not split static from kinetic. From a known μ and a mass you compute T next door on friction force: 0.4 and 10 kg on the flat give about 39 N again.
A slide with this μ lives on incline with friction. There a = g(sin α - μ cos α), and at 30° with 0.2 you get about 3.21 m/s². Here you go from T and N to μ, not the other way. The incline angle is not a field in this calculator.
μ is not a force and not an angle. The angle belongs on the incline pages. This calculator ends at the ratio. The unit switch does not give μ a unit. The header symbol does not hold the block.
Type 39.24 and 98.1, click Calculate, and match 0.4. Then 20 and 400 for 0.05. Treat 0.4 as a number from the problem, not as newtons on a scale.
How to use
- In the first field enter friction T in newtons, for example 39.24.
- In the second field enter normal force N in newtons, for example 98.1. Zero will not run, because you divide by N.
- Click Calculate. The calculator divides T by N. 39.24 and 98.1 give μ = 0.4.
- N must be positive. Typed 0 in T gives μ = 0. Both fields need a number.
- With a known μ, open friction force. A slide with μ is on incline with friction.
Formula
μ = T / N
Dimensionless.
μ from the T over N quotient
The friction coefficient here is μ = T/N. 39 N on 98 N is 0.4. The result has no unit. Zero N does not divide.
- μ
- Coefficient, no unit. 39.24 / 98.1 = 0.4. Not newtons.
- T
- Friction force [N]. 39 N or 20 N. An input, not a result.
- N
- Normal force [N]. 98 N. N must be positive.
Real-life examples
Example 2
T = 20 N, N = 400 N.
Example 3
T = 9000 N, N = 12000 N.
Example 4
T = 60 N, N = 200 N.
Example 5
T = 15 N, N = 80 N.
Example 6
T = 8.49 N, N = 42.45 N.
Example 7
T = 30 N, N = 250 N.
Example 8
T = 40 N, N = 100 N.
Example 9
T = 50 N, N = 200 N.
Ways to use this calculator
- You compute μ from T = 39 N and N = 98 N.
- You check that 20 N on 400 N is 0.05.
Frequently asked questions
What is μ at T = 39.24 N and N = 98.1 N?
The coefficient is 0.4. That is 39.24 / 98.1. 40 N on 100 N also gives 0.4, the same order.
Is 0.4 in newtons?
No. μ has no unit. 0.4 is four tenths, not 0.4 N. T and N are in newtons; the quotient is not.
Which units do I type?
Friction T [N] and normal force N [N]. Result μ with no unit. Multiply kilograms by g first if the problem gives mass.
How much at 20 N on 400 N?
You get μ = 0.05. At 60 N on 200 N that is 0.3. At 15 N on 80 N that is 0.1875.
How is this different from friction force?
Here T and N give μ. There μ and m give T. 0.4 and 10 kg on the flat give about 39 N, the inverse unknown.
Can N be 0?
No. Zero normal force does not divide. The normal force must be positive. Both fields need a number.
μ_s or μ_k?
The calculator computes one μ from T/N. The problem says whether it is static or kinetic. The fields do not split them.
Does a comma in 39.24 work?
Yes. 39.24 and 39,24 are the same T [N]. A comma and a period mean the same value.
Where is a slide with this μ?
On the incline-with-friction page. At 30° and μ = 0.2, a is about 3.21 m/s². Here μ is the result, there it is a given.
How much at 9000 N and 12,000 N?
The coefficient is 0.75. At 8.49 N and 42.45 N you get 0.2. Same quotient, another scale.
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.