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Screw Strength — Calculator

Calculate withdrawal and lateral capacity for wood screws, lag bolts and nails. NDS 2018, Eurocode 5, IS 883:2016, AS 1720 with group factor.

Fastener, Unit & Standard

Fastener Type

Unit System

Design Standard

Fastener Dimensions

Shank Diameter (d)

Penetration into Base Wood

Number of Fasteners

pcs

Wood Species & Load Direction

Wood Species (sets density)

Density (kg/m³)

kg/m³

Load Direction

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Fastener Strength Results

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Single Fastener

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Group Total

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Weight Capacity

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N/mm

Per mm Penetration

Connection Strength Rating

Formula Trace

🔩 Screw Strength Calculator

Determines how much load a wood fastener can carry before failing — axially (withdrawal) or sideways (lateral shear). Critical for safe furniture joints, structural timber connections, decking and cabinet installations.

Where Used?

Furniture AssemblyStructural TimberDeckingDoor HingesShelf BracketsLedger Boards

Formulas

IS 883:2016 — W = k × d × L (k = 12/10/7/5 by density group)NDS 2018 — W = 124.9 × G^1.5 × D^0.75 (lbs/in penetration)Eurocode 5 — f_ax,k = 0.52 × d^-0.5 × L^-0.1 × ρ^0.8Group factor — Cg = max(0.4, 1 − 0.05×(n−1))

FAQ

IS 883:2016 density groups?

Group A (>800 kg/m³) k=12 — Sal, Ebony, Ipe; Group B (601–800) k=10 — Teak, Shisham; Group C (401–600) k=7 — Deodar, Douglas Fir; Group D (≤400) k=5 — Paulownia, Western Red Cedar.

Minimum penetration depth?

Minimum 10× shank diameter in softwoods, 8× in hardwoods. NDS: 2/3 of total length in base member. IS 883: minimum 6D for withdrawal calculations.

Screw Strength Calculator

Screw Strength — Calculator

🔩 Screw Strength Calculator

Where Used?

Formulas

FAQ

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