Bolt and Nut Weight Calculator

Bolt and Nut Weight Calculator

Carbon Steel (7.85g/cm³) Stainless Steel (8.00g/cm³) Brass (8.50g/cm³) Aluminum (2.70g/cm³)
Yes (Bolt + Nut) No (Bolt Only)

Estimation Results:

Weight per Unit: 0 kg

Total Batch Weight: 0 kg

Guide to Calculating Bolt and Nut Weights

In structural engineering and manufacturing, knowing the precise weight of fasteners is crucial for shipping logistics, structural load calculations, and inventory management. This bolt and nut weight calculator helps you estimate the mass of standard hexagonal bolts and their corresponding nuts based on material density and dimensions.

How the Calculation Works

The weight of a bolt is determined by its volume and the density of the material it is made from. The volume consists of two main parts: the shank (cylinder) and the head (hexagonal prism).

  • Shank Volume: Calculated using the formula for a cylinder: π × (Radius)² × Length.
  • Head Volume: Generally estimated based on the diameter. For standard hex bolts, the head volume is roughly 50% of a cylinder with the same diameter and a height of 0.7 × Diameter.
  • Nut Volume: A standard nut is typically estimated to have a volume approximately 60% of the equivalent shank volume for a length equal to the diameter.

Material Density Reference

Material Density (g/cm³)
Carbon Steel 7.85
Stainless Steel (304/316) 8.00
Aluminum 2.70
Brass 8.50

Example Calculation

If you have an M10 Carbon Steel Bolt with a 50mm length:

  1. Radius = 5mm.
  2. Shank Volume = 3.14159 × 5² × 50 = 3,927 mm³.
  3. Head Volume (Approx) = 1,100 mm³.
  4. Total Volume ≈ 5,027 mm³ (or 5.027 cm³).
  5. Weight = 5.027 cm³ × 7.85 g/cm³ = 39.46 grams per bolt.
function calculateBoltWeight() { var diameter = parseFloat(document.getElementById('diameter').value); var length = parseFloat(document.getElementById('length').value); var density = parseFloat(document.getElementById('material').value); var quantity = parseInt(document.getElementById('quantity').value); var includeNut = document.getElementById('includeNut').value; if (isNaN(diameter) || isNaN(length) || isNaN(quantity) || diameter <= 0 || length <= 0) { alert("Please enter valid positive dimensions and quantity."); return; } var radius = diameter / 2; // Volume of Shank (Cylinder) in mm^3 var shankVolume = Math.PI * Math.pow(radius, 2) * length; // Volume of Hex Head (Estimation: 0.7 * D is standard height, 1.8 * D is standard width across flats) // Simplified engineering approximation for Hex Head Volume: var headVolume = 0.65 * (Math.PI * Math.pow(radius, 2) * diameter); var totalBoltVolume = shankVolume + headVolume; var unitVolume = totalBoltVolume; // Add Nut Volume if selected // Standard nut volume approximation (Height approx 0.8D, Width approx 1.8D) if (includeNut === 'yes') { var nutVolume = 0.9 * (Math.PI * Math.pow(radius, 2) * diameter); unitVolume += nutVolume; } // Convert mm^3 to cm^3 (divide by 1000) var volumeCm3 = unitVolume / 1000; // Weight in grams var weightGrams = volumeCm3 * (density * 1000) / 1000; // Calculation: density is in g/mm^3 equivalent when we use the specific select values: // Actually the select values are g/cm3, so we use volumeCm3 directly var unitWeightKg = (volumeCm3 * density) / 1000; var totalWeightKg = unitWeightKg * quantity; document.getElementById('weightPerUnit').innerText = unitWeightKg.toFixed(4); document.getElementById('totalWeight').innerText = totalWeightKg.toFixed(3); document.getElementById('results-box').style.display = 'block'; }

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