Tolerance Lab
Free
Analyze linear tolerance stacks with worst-case, RSS, and sensitivity contribution views.
CalculatorFree
Bolt Size & Torque
Calculate stress area and preload from nominal diameter, pitch, and grade.
Calculator tabs
Input Parameters
Calculate preload and tightening torque from size, property class, and an empirical torque-factor K preset. K is not a standalone coefficient of friction.
Choosing a preset fills d and P automatically; you can still edit both fields.
Calculation Results
Stress area, preload, and tightening torque calculated with empirical torque factor K.
Stress area As36.6 mm²
Preload Fv16.40 kN
Torque factor K0.25
Calculated tightening torque T32.8 N·m
Yield strength Re640 MPa
Proof strengthNot used by this simplified model
Tensile stress σ448 MPa
Safety factor against yield S1.43
In T = K·F·d, K is an empirical torque factor combining thread, bearing-surface, lubrication, and coating effects. It is not the coefficient of friction μ.
Explanation Mode (advanced)
Formulas used
As = (pi/4) * (d - 0.9382 * P)^2
Fv = preload * Re * As
T = K * Fv * d
sigma = Fv / As
S = Re / sigma
Variables
- d
- Nominal çap (mm).
- P
- Diş adımı (mm).
- As
- Gerilme alanı (mm^2).
- Re
- Akma dayanımı (MPa).
- Fv
- Ön yük (N).
- K
- Empirical torque/nut factor; not μ.
- T
- Tork (Nm). d metreye çevrilerek kullanılır.
- sigma
- Çekme gerilmesi (MPa).
- S
- Güvenlik katsayısı.
Usage notes
- Metrik dişler için yaklaşık gerilme alanı formülü kullanılır.
- K should be verified experimentally for the joint geometry, lubrication, and coating.
- Use a detailed joint model such as VDI 2230 for critical connections.
Show reports, charts, and comparison tools
After checking the basic result, open sharing, PDF, method notes, and comparison panels.
Tool-Specific Documentation
Bolt Size & TorqueScope: What does this tool calculate?
Calculates bolt stress area, preload estimate, and tightening torque estimate.
Assumptions and Units
- SI units are used (N, mm, MPa, Nm).
- Thread geometry and friction values use typical defaults and must be adjusted per application.
- Material grade mechanical properties are interpreted against ISO 898-1 references.
Limits / Boundaries
- Torque-preload relation is highly friction-sensitive; real assembly requires calibration.
- Dynamic fatigue, relaxation, and service temperature effects are limited in this quick model.
Applicable References
- ISO 898-1
- VDI 2230
- ISO 68-1 / ISO 261 (metric thread baseline references)
Validation Example
M10 - class 8.8 check
| Input | Expected Output |
|---|---|
| d=10 mm, p=1.5 mm, target preload=25 kN, friction=0.14 | As around 58 mm^2, estimated torque around 45-55 Nm |
Note: For final torque, verify with field friction data and wrench calibration.
Version and Update
- Version
- v1.0.0
- Last updated
- 2026-03-04
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