{
  "id": "swing-weight",
  "version": "16579b332f6d",
  "status": "published",
  "name": "Swing Weight Calculator",
  "question": "What is my club’s swing weight?",
  "summary": "Works out a golf club’s swing weight on the Lorythmic scale (A0 to G9) from its weight and balance point, and the head weight to add or remove to reach a target swing weight.",
  "category": "sports",
  "subcategory": "fitness",
  "url": "https://www.acalculator.org/sports/swing-weight-calculator",
  "markdown": "https://www.acalculator.org/sports/swing-weight-calculator.md",
  "kind": "function",
  "method": "Moment = club weight (oz) × (balance point (in) − 14); points = (moment − 161) ÷ 1.75, where 0 is A0, 10 is B0, 20 is C0, 30 is D0; head change = (target points − points) × 1.75 ÷ (club length − 14).",
  "assumptions": [
    "The Lorythmic scale: a fulcrum 14 inches from the grip end, C0 = 196 inch-ounces and 1.75 inch-ounces a point.",
    "The swing weight shown is the nearest whole point; halves round up.",
    "Added head weight sits at the club length from the grip end."
  ],
  "inputs": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
      "w": {
        "title": "Club weight",
        "description": "The total weight of the club: head, shaft and grip.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "mass",
        "exclusiveMinimum": 0,
        "maximum": 10
      },
      "bp": {
        "title": "Balance point",
        "description": "How far from the grip end the club balances on a knife edge.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "length",
        "exclusiveMinimum": 0,
        "maximum": 5
      },
      "t": {
        "title": "Target swing weight",
        "description": "The swing weight you want, a letter A to G and a digit 0 to 9, such as D2. Leave it empty to skip.",
        "type": "string",
        "maxLength": 5
      },
      "len": {
        "title": "Club length",
        "description": "The club’s length from the grip end; head weight is taken to sit this far from the grip end.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "length",
        "exclusiveMinimum": 0,
        "maximum": 5
      }
    }
  },
  "outputs": {
    "swingWeight": {
      "label": "Swing weight",
      "description": "The Lorythmic swing weight, to the nearest point (halves round up).",
      "format": "text"
    },
    "moment": {
      "label": "Moment (inch-ounces)",
      "description": "Club weight in ounces × (balance point in inches − 14).",
      "format": "number"
    },
    "points": {
      "label": "Points above A0",
      "description": "(Moment − 161) ÷ 1.75: 0 is A0, 30 is D0, 69 is G9.",
      "format": "number"
    },
    "exact": {
      "label": "Swing weight to a tenth",
      "description": "The swing weight with tenths of a point, such as D1.4.",
      "format": "text"
    },
    "changeOz": {
      "label": "Head weight change (oz)",
      "description": "Weight to add at the head (or remove, when negative) to reach the target, in ounces.",
      "format": "number"
    },
    "changeG": {
      "label": "Head weight change (g)",
      "description": "The same change in grams.",
      "format": "number"
    },
    "advice": {
      "label": "To reach the target",
      "description": "What to do to reach the target swing weight.",
      "format": "text"
    }
  },
  "defaultAnswer": {
    "inputs": {
      "w": "11 oz",
      "bp": "33.5 in",
      "t": "D2",
      "len": "45.5 in"
    },
    "outputs": {
      "swingWeight": "D1",
      "moment": 214.5,
      "points": 30.571428571428573,
      "exact": "D0.6",
      "changeOz": 0.07936507936507936,
      "changeG": 2.2499621527777776,
      "advice": "Add 2.25 g at the head to reach D2"
    },
    "text": "A club of 11 oz balancing at 33.5 in has a swing weight of D1."
  },
  "examples": [
    {
      "given": {
        "w": 0.34019427750000003,
        "bp": 0.8128
      },
      "expect": {
        "moment": 216,
        "points": 31.428571428571427,
        "swingWeight": "D1",
        "exact": "D1.4"
      },
      "source": "Dave Tutelman, Design Notes, Heft: swingweight and MOI, page 4 (swingweight = club weight × (balance point − 14 in); C-0 = 196.00 in-oz, D-0 = 213.50 in-oz, 1.75 in-oz a point), https://www.tutelman.com/golf/design/swingwt4.php (retrieved 2026-10-02); hand calculation in content.mdx: 12 × (32 − 14) = 216 in-oz; (216 − 161) ÷ 1.75 = 31.43 points, D1"
    },
    {
      "given": {
        "w": 0.4110680853125,
        "bp": 0.6985
      },
      "expect": {
        "moment": 195.75,
        "points": 19.857142857142858,
        "swingWeight": "C0",
        "exact": "B9.9"
      },
      "source": "Dave Tutelman, Design Notes, Heft: swingweight and MOI, page 4 (swingweight = club weight × (balance point − 14 in); C-0 = 196.00 in-oz, D-0 = 213.50 in-oz, 1.75 in-oz a point), https://www.tutelman.com/golf/design/swingwt4.php (retrieved 2026-10-02); hand calculation in content.mdx: 14.5 × 13.5 = 195.75 in-oz, 0.25 below C0 (196), so 19.86 points rounds to C0"
    },
    {
      "given": {
        "w": 0.34019427750000003,
        "bp": 0.8128,
        "t": "D3",
        "len": 1.143
      },
      "expect": {
        "changeOz": 0.08870967741935484,
        "changeG": 2.51487705141129
      },
      "source": "Dave Tutelman, Design Notes, Heft: swingweight and MOI, page 4 (swingweight = club weight × (balance point − 14 in); C-0 = 196.00 in-oz, D-0 = 213.50 in-oz, 1.75 in-oz a point), https://www.tutelman.com/golf/design/swingwt4.php (retrieved 2026-10-02); hand calculation in content.mdx: (33 − 31.4286) × 1.75 = 2.75 in-oz ÷ (45 − 14) = 0.0887 oz = 2.51 g"
    },
    {
      "given": {
        "w": 0.3,
        "bp": 0.8
      },
      "expect": {
        "moment": 185.1466380755142,
        "points": 13.798078900293827,
        "swingWeight": "B4",
        "exact": "B3.8"
      },
      "source": "Dave Tutelman, Design Notes, Heft: swingweight and MOI, page 4 (swingweight = club weight × (balance point − 14 in); C-0 = 196.00 in-oz, D-0 = 213.50 in-oz, 1.75 in-oz a point), https://www.tutelman.com/golf/design/swingwt4.php (retrieved 2026-10-02); hand calculation in content.mdx: 300 g = 10.5822 oz, 80 cm = 31.4961 in; 10.5822 × 17.4961 = 185.15 in-oz; (185.15 − 161) ÷ 1.75 = 13.80 points, B4"
    }
  ],
  "sources": [
    "Dave Tutelman, Design Notes, Heft: swingweight and MOI, page 4 (swingweight is the torque about an axis 14 inches from the butt: balance point minus 14 inches, times the club weight; conversion table C-0 = 196.00 in-oz, C-5 = 204.75, D-0 = 213.50, D-5 = 222.25, E-0 = 231.00, 1.75 in-oz per point). https://www.tutelman.com/golf/design/swingwt4.php (retrieved 2026-10-02)"
  ],
  "related": [
    "golf-handicap",
    "one-rep-max"
  ],
  "changelog": []
}