Bolt Weight & Quantity Calculator

import math

def bolt_assembly_weight(dia_mm, length_mm, s_mm, k_mm, m_mm, dw_mm, hw_mm, qty=1, include_nut=True, washers=2, density_kg_m3=7850):
    """
    Calculate mass of hex bolt, nut, and washer assembly.
    """
    rho_g_mm3 = density_kg_m3 * 1e-6
    
    # Shank
    shank_vol = math.pi * (dia_mm / 2.0)**2 * length_mm
    # Hex Head
    hex_area = (math.sqrt(3) / 2.0) * (s_mm ** 2)
    head_vol = hex_area * k_mm
    bolt_mass = (shank_vol + head_vol) * rho_g_mm3

    # Nut
    nut_vol = (hex_area - math.pi * (dia_mm / 2.0)**2) * m_mm if include_nut else 0.0
    nut_mass = nut_vol * rho_g_mm3

    # Washers
    washer_vol = math.pi * ((dw_mm / 2.0)**2 - ((dia_mm + 1) / 2.0)**2) * hw_mm * washers
    washer_mass = washer_vol * rho_g_mm3

    unit_mass_g = bolt_mass + nut_mass + washer_mass
    total_kg = (unit_mass_g * qty) / 1000.0

    return {
        "unit_weight_g": round(unit_mass_g, 1),
        "total_weight_kg": round(total_kg, 2),
        "total_tonnage": round(total_kg / 1000.0, 3)
    }

# Example (M16 x 65 mm)
res = bolt_assembly_weight(
    dia_mm=16,
    length_mm=65,
    s_mm=24,
    k_mm=10,
    m_mm=13,
    dw_mm=30,
    hw_mm=3,
    qty=500,
    include_nut=True,
    washers=2
)

print(f"Single Assembly Weight: {res['unit_weight_g']} grams")
print(f"Total Lot Mass: {res['total_weight_kg']} kg")

function [m_unit_g, total_kg] = bolt_weight(d, L, s, k, m, dw, hw, Q, has_nut, n_washers, rho)
    % Hex bolt assembly mass calculator
    if nargin < 11, rho = 7850; end
    rho_g = rho * 1e-6;

    shank_v = pi * (d / 2)^2 * L;
    hex_a = (sqrt(3)/2) * s^2;
    head_v = hex_a * k;
    nut_v = (hex_a - pi * (d / 2)^2) * m * has_nut;
    washer_v = pi * ((dw / 2)^2 - ((d + 1) / 2)^2) * hw * n_washers;

    m_unit_g = (shank_v + head_v + nut_v + washer_v) * rho_g;
    total_kg = (m_unit_g * Q) / 1000;
end

% Example
[w_g, w_tot] = bolt_weight(16, 65, 24, 10, 13, 30, 3, 500, 1, 2);
fprintf('Unit Assembly Mass: %.1f g\n', w_g);
fprintf('Total Batch Mass: %.2f kg\n', w_tot);