{
  "id": "marginal-benefit",
  "version": "ef6dd14a638d",
  "status": "published",
  "name": "Marginal Benefit Calculator",
  "question": "How much is the marginal benefit?",
  "summary": "Computes marginal benefit, the change in total benefit divided by the change in quantity, and compares it with marginal cost to say whether one more unit is worth it.",
  "category": "finance",
  "subcategory": "business",
  "url": "https://www.acalculator.org/finance/marginal-benefit-calculator",
  "markdown": "https://www.acalculator.org/finance/marginal-benefit-calculator.md",
  "kind": "function",
  "method": "Marginal benefit = (TB₂ − TB₁) ÷ (Q₂ − Q₁), where TB is total benefit at quantity Q. With a marginal cost MC: do more when MB > MC, do less when MB < MC, and stop where MB = MC.",
  "assumptions": [
    "Total benefit is in one unit throughout, such as dollars of willingness to pay or points.",
    "Over more than one unit, the result is the average marginal benefit of each extra unit in that range.",
    "Arithmetic is exact on the typed decimals; results show up to 6 decimals (6 significant figures below 0.0001 in size)."
  ],
  "inputs": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
      "q1": {
        "title": "Starting quantity",
        "description": "Units of the good or activity at the start.",
        "type": "number",
        "minimum": 0,
        "maximum": 1000000000000000
      },
      "b1": {
        "title": "Total benefit at the start",
        "description": "The total benefit of the starting quantity, in dollars or any unit such as points.",
        "type": "number",
        "minimum": -1000000000000000,
        "maximum": 1000000000000000
      },
      "q2": {
        "title": "New quantity",
        "description": "Units of the good or activity after the change.",
        "type": "number",
        "minimum": 0,
        "maximum": 1000000000000000
      },
      "b2": {
        "title": "Total benefit at the new quantity",
        "description": "The total benefit of the new quantity, in the same unit.",
        "type": "number",
        "minimum": -1000000000000000,
        "maximum": 1000000000000000
      },
      "mc": {
        "title": "Marginal cost of each extra unit",
        "description": "What each extra unit costs, in the same unit as the benefit, to compare with the marginal benefit. Optional.",
        "type": "number",
        "minimum": -1000000000000000,
        "maximum": 1000000000000000
      }
    }
  },
  "outputs": {
    "mb": {
      "label": "Marginal benefit",
      "description": "Change in total benefit ÷ change in quantity: the benefit of each extra unit.",
      "format": "number"
    },
    "dBenefit": {
      "label": "Change in total benefit",
      "description": "New total benefit − starting total benefit.",
      "format": "number"
    },
    "dQuantity": {
      "label": "Change in quantity",
      "description": "New quantity − starting quantity.",
      "format": "number"
    },
    "net": {
      "label": "Marginal benefit − marginal cost",
      "description": "The net gain from each extra unit, when a marginal cost is given.",
      "format": "number"
    },
    "decision": {
      "label": "Marginal decision rule",
      "description": "More when marginal benefit is above marginal cost, less when below, stop where they are equal.",
      "format": "text"
    }
  },
  "defaultAnswer": {
    "inputs": {
      "q1": 2,
      "b1": 32,
      "q2": 3,
      "b2": 42
    },
    "outputs": {
      "mb": 10,
      "dBenefit": 10,
      "dQuantity": 1
    },
    "text": "From a quantity of 2 to 3, total benefit changes by 10: a marginal benefit of 10 per unit."
  },
  "examples": [
    {
      "given": {
        "q1": 2,
        "b1": 32,
        "q2": 3,
        "b2": 42
      },
      "expect": {
        "mb": 10,
        "dBenefit": 10,
        "dQuantity": 1
      },
      "source": "Principles of Economics v2.0 (Saylor Academy open textbook, CC BY-NC-SA 3.0), 6.1 The Logic of Maximizing Behavior (marginal benefit is the amount by which an additional unit of an activity increases its total benefit; Laurie Phan’s economics study: total benefit 18, 32 and 42 points after 1, 2 and 3 hours, 50 after 5; marginal benefits 18, 14 and 10 points; net benefit is largest where marginal benefit equals marginal cost). https://saylordotorg.github.io/text_principles-of-economics-v2.0/s09-01-the-logic-of-maximizing-behavi.html: 42 − 32 = 10 points"
    },
    {
      "given": {
        "q1": 1,
        "b1": 18,
        "q2": 2,
        "b2": 32
      },
      "expect": {
        "mb": 14
      },
      "source": "Principles of Economics v2.0 (Saylor Academy open textbook, CC BY-NC-SA 3.0), 6.1 The Logic of Maximizing Behavior (marginal benefit is the amount by which an additional unit of an activity increases its total benefit; Laurie Phan’s economics study: total benefit 18, 32 and 42 points after 1, 2 and 3 hours, 50 after 5; marginal benefits 18, 14 and 10 points; net benefit is largest where marginal benefit equals marginal cost). https://saylordotorg.github.io/text_principles-of-economics-v2.0/s09-01-the-logic-of-maximizing-behavi.html: 32 − 18 = 14 points"
    },
    {
      "given": {
        "q1": 3,
        "b1": 42,
        "q2": 5,
        "b2": 50,
        "mc": 6
      },
      "expect": {
        "mb": 4,
        "net": -2,
        "decision": "Do less: each extra unit costs more than the benefit it adds."
      },
      "source": "Principles of Economics v2.0 (Saylor Academy open textbook, CC BY-NC-SA 3.0), 6.1 The Logic of Maximizing Behavior (marginal benefit is the amount by which an additional unit of an activity increases its total benefit; Laurie Phan’s economics study: total benefit 18, 32 and 42 points after 1, 2 and 3 hours, 50 after 5; marginal benefits 18, 14 and 10 points; net benefit is largest where marginal benefit equals marginal cost). https://saylordotorg.github.io/text_principles-of-economics-v2.0/s09-01-the-logic-of-maximizing-behavi.html; hand calculation in content.mdx: (50 − 42) ÷ (5 − 3) = 4 points an hour, below a cost of 6"
    },
    {
      "given": {
        "q1": 1.5,
        "b1": 12.25,
        "q2": 4,
        "b2": 20.5,
        "mc": 3.3
      },
      "expect": {
        "mb": 3.3,
        "net": 0,
        "decision": "Stop here: marginal benefit equals marginal cost, where net benefit is largest."
      },
      "source": "Principles of Economics v2.0 (Saylor Academy open textbook, CC BY-NC-SA 3.0), 6.1 The Logic of Maximizing Behavior (marginal benefit is the amount by which an additional unit of an activity increases its total benefit; Laurie Phan’s economics study: total benefit 18, 32 and 42 points after 1, 2 and 3 hours, 50 after 5; marginal benefits 18, 14 and 10 points; net benefit is largest where marginal benefit equals marginal cost). https://saylordotorg.github.io/text_principles-of-economics-v2.0/s09-01-the-logic-of-maximizing-behavi.html; hand calculation in content.mdx: (20.5 − 12.25) ÷ (4 − 1.5) = 8.25 ÷ 2.5 = 3.3"
    }
  ],
  "sources": [
    "Principles of Economics v2.0 (Saylor Academy open textbook, CC BY-NC-SA 3.0), 6.1 The Logic of Maximizing Behavior: the marginal benefit is the amount by which an additional unit of an activity increases its total benefit, and it equals the slope of the total benefit curve; Laurie Phan expects 18, 32 and 42 points from 1, 2 and 3 hours of economics study and 50 points from 5, so the first three hours add 18, 14 and 10 points; if the marginal benefit exceeds the marginal cost the activity should be increased, and net benefit is maximized where marginal benefit equals marginal cost. https://saylordotorg.github.io/text_principles-of-economics-v2.0/s09-01-the-logic-of-maximizing-behavi.html (retrieved 2026-10-19)",
    "OpenStax, Principles of Microeconomics 3e, 6.1 Consumption Choices: the marginal value of one more unit is the change in the total divided by the change in quantity (marginal utility = change in total utility ÷ change in quantity), and it usually diminishes. https://openstax.org/books/principles-microeconomics-3e/pages/6-1-consumption-choices (retrieved 2026-10-19)"
  ],
  "related": [
    "marginal-cost",
    "marginal-utility",
    "marginal-revenue",
    "consumer-surplus"
  ],
  "changelog": []
}