Bolting — Hole Type & Size Allowance
Hole diameter and washer rules for standard, oversize and slotted holes.
Standard holes run bolt+2 mm (or +1/16"); oversize and slotted holes buy erection tolerance at the price of washer rules and, in slip-critical joints, reduced capacity factors. The hole schedule is erection-speed policy written in millimetres.
Formula
Note: Erection-planning estimate only. Member weights, connection capacities and tolerances for execution must come from the issued drawings, the EOR and the erection engineer — never from a generic calculator.
Hole diameter and washer rules for standard, oversize and slotted holes. A free structural steel delivery & erection tool — no sign-up, no upload, instant results in your browser.
About Bolting — Hole Type & Size Allowance
Bolting — Hole Type & Size Allowance computes the governing relationship std = d+2 mm · oversize d+6/8 · short slot (d+2)×(d+8/10) · long slot (d+2)×2.5d live as you type. Standard holes run bolt+2 mm (or +1/16"); oversize and slotted holes buy erection tolerance at the price of washer rules and, in slip-critical joints, reduced capacity factors. The hole schedule is erection-speed policy written in millimetres. Defaults are pre-filled with realistic values for this exact scenario, and the worked example substitutes your numbers step by step so the math is never a black box.
How to use Bolting — Hole Type & Size Allowance
- 1Enter your values — Bolt diameter, Hole (1 std · 2 oversize · 3 short slot · 4 long slot) (sensible defaults are pre-filled).
- 2Read the live results: Hole size (or slot width), Slot length (if slotted).
- 3Check the "with your numbers" line to see std = d+2 mm · oversize d+6/8 · short slot (d+2)×(d+8/10) · long slot (d+2)×2.5d substituted step by step.
- 4Adjust inputs until the scenario matches yours, then copy or share the result.
Why use Bolting — Hole Type & Size Allowance?
- ✓Instant, free and private — every calculation runs client-side in your browser; nothing is uploaded
- ✓Built on the stated formula std = d+2 mm · oversize d+6/8 · short slot (d+2)×(d+8/10) · long slot (d+2)×2.5d with authoritative sources cited on the page (RCSC — Specification for Structural Joints Using High-Strength Bolts; AISC 360 — Specification for Structural Steel Buildings)
- ✓Standard holes run bolt+2 mm (or +1/16"); oversize and slotted holes buy erection tolerance at the price of washer rules and, in slip-critical joints, reduced capacity factors.
- ✓SI ⇄ Imperial toggle converts your inputs in place, so you can work in the units your drawings use
Frequently asked questions
What formula does the bolting — hole type & size allowance use?+
It evaluates std = d+2 mm · oversize d+6/8 · short slot (d+2)×(d+8/10) · long slot (d+2)×2.5d, exactly as published. Sources: RCSC — Specification for Structural Joints Using High-Strength Bolts; AISC 360 — Specification for Structural Steel Buildings. The substituted worked example on the page lets you verify every step against the textbook.
How should I read the result — and how far can I trust it?+
Standard holes run bolt+2 mm (or +1/16"); oversize and slotted holes buy erection tolerance at the price of washer rules and, in slip-critical joints, reduced capacity factors. Erection-planning estimate only. Member weights, connection capacities and tolerances for execution must come from the issued drawings, the EOR and the erection engineer — never from a generic calculator.
When is this calculator the right tool for the job?+
Hole diameter and washer rules for standard, oversize and slotted holes. A free structural steel delivery & erection tool. The hole schedule is erection-speed policy written in millimetres. For neighbouring scenarios, the related tools below cover the same engine with different presets.
Does it support both metric and imperial units?+
Yes — the SI ⇄ Imperial toggle converts the values already in the fields, preserving the physical quantity, so you can flip mid-calculation without re-entering anything.
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