🧮 在线计算器：Bolt Pre-selection Calculator — Fast sizing with the Kübler equation; supports a design mode and a check mode.

A minimal preliminary estimation table for bolt size

📎 Series article: this is a standalone spin-off of Bolt Pre-selection (001) — From Load to Size , focusing on the table-lookup method that needs no calculation. For a precise estimate, see the Kübler equation in that article.

On the shop floor or in technical discussion, you often need a rough judgement of bolt size in seconds: “for this load, roughly how large a bolt do I need?” The quick pre-selection list below is made for exactly that — knowing only the maximum working load a single bolt carries, you can read the recommended nominal diameter and minimum property class directly.

⚠️ For teaching reference only: the quick pre-selection list below is only an auxiliary reference for engineering teaching; it does not replace a formal design calculation based on DIN/ISO standards. In real engineering, use the Kübler equation or the full VDI 2230-1 method.

How to use

1. Determine the maximum working load a single bolt carries (axial static load / axial dynamic load / transverse shear force)
2. Find the range not smaller than that load below
3. Choose a suitable nominal diameter and property-class combination from those listed

Quick pre-selection list

Working load $\le$ 1.6 kN (static) / 1.0 kN (dynamic) / 0.32 kN (shear)

Working load $\le$ 2.5 kN (static) / 1.6 kN (dynamic) / 0.5 kN (shear)

Working load $\le$ 4.0 kN (static) / 2.5 kN (dynamic) / 0.8 kN (shear)

Working load $\le$ 6.3 kN (static) / 4.0 kN (dynamic) / 1.25 kN (shear)

Working load $\le$ 10.0 kN (static) / 6.3 kN (dynamic) / 2.0 kN (shear)

Working load $\le$ 16.0 kN (static) / 10.0 kN (dynamic) / 3.15 kN (shear)

Working load $\le$ 25.0 kN (static) / 16.0 kN (dynamic) / 5.0 kN (shear)

Working load $\le$ 40.0 kN (static) / 25.0 kN (dynamic) / 8.0 kN (shear)

Working load $\le$ 63.0 kN (static) / 40.0 kN (dynamic) / 12.5 kN (shear)

Working load $\le$ 100 kN (static) / 63 kN (dynamic) / 20 kN (shear)

Working load $\le$ 160 kN (static) / 100 kN (dynamic) / 31.5 kN (shear)

Working load $\le$ 250 kN (static) / 160 kN (dynamic) / 50 kN (shear)

Notes

[!NOTE] Applicability limits

• For reduced-shank bolts (German: Dehnschrauben), or when the load point is eccentric and the tightening factor $k_A$ is large, choose the next larger nominal diameter.
• The data in the table are based on the typical case of a standard hexagon-head bolt, normal lubrication conditions and torque-controlled tightening.
• For safety-critical applications, always use the Kübler equation or the full VDI 2230-1 method for a precise check.

Data basis and accuracy statement

This table is a rough pre-selection (grobe Vorwahl), with an accuracy at the order-of-magnitude level, only for narrowing the selection range.

Data sources:

• DIN 13-1 (ISO 261) — metric ISO thread geometry
• DIN EN ISO 898-1 — bolt mechanical properties (property class and $R_{p0.2}$)

Disclaimer: This article is for engineering estimation and teaching reference only. The results do not replace a professional engineer’s design judgement and final sign-off. The final responsibility for engineering safety verification rests with the user.

📚 Series navigation

← Previous: Thread Basics ｜ Bolt Pre-selection (001) — Precise Pre-selection with the Kübler Equation →