{
  "id": "pro-rata",
  "version": "8fdbafe4c4ff",
  "status": "published",
  "name": "Pro Rata Calculator",
  "question": "What is the pro rata share?",
  "summary": "Works out a pro rata share: an amount × part ÷ whole, such as a part-time salary or a bill for days used, or an amount split among several people in proportion to their shares.",
  "category": "finance",
  "subcategory": "business",
  "url": "https://www.acalculator.org/finance/pro-rata-calculator",
  "markdown": "https://www.acalculator.org/finance/pro-rata-calculator.md",
  "kind": "function",
  "method": "Pro rata amount = full amount × part ÷ whole. In a split, each party gets full amount × its units ÷ all units.",
  "assumptions": [
    "The part and the whole are in the same units (hours, days, shares, square feet).",
    "A part larger than the whole gives more than the full amount, as with overtime.",
    "Amounts in the split list are rounded to the cent one by one, so they can differ from the full amount by a few cents in total."
  ],
  "inputs": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
      "mode": {
        "title": "Work out",
        "description": "One share of an amount, or the amount split among several parties.",
        "type": "string",
        "enum": [
          "share",
          "split"
        ]
      },
      "amt": {
        "title": "Full amount",
        "description": "The whole amount to share out: a full-time salary, a yearly bill, a dividend or a cost.",
        "type": "number",
        "x-unit": "USD",
        "minimum": 0,
        "maximum": 1000000000000
      },
      "part": {
        "title": "Your part",
        "description": "Your part of the whole, such as hours worked, days used or shares owned.",
        "type": "number",
        "minimum": 0,
        "maximum": 1000000000000
      },
      "whole": {
        "title": "The whole",
        "description": "The whole the full amount is for, in the same units as your part.",
        "type": "number",
        "minimum": 1e-9,
        "maximum": 1000000000000
      },
      "parties": {
        "title": "Parties",
        "description": "Each party’s units: shares owned, days, hours or any measure of their part.",
        "type": "array",
        "items": {
          "type": "object",
          "properties": {
            "u": {
              "title": "Units",
              "description": "This party’s units.",
              "type": "number",
              "minimum": 0,
              "maximum": 1000000000000
            }
          }
        }
      }
    }
  },
  "outputs": {
    "share": {
      "label": "Pro rata amount",
      "description": "Full amount × part ÷ whole (in a split, the first party’s amount).",
      "format": "money"
    },
    "percent": {
      "label": "Share of the whole",
      "description": "Part ÷ whole × 100 (in a split, the first party’s share).",
      "format": "percent"
    },
    "rest": {
      "label": "Rest of the amount",
      "description": "Full amount minus the pro rata amount.",
      "format": "money"
    },
    "perUnit": {
      "label": "Amount per unit",
      "description": "Full amount ÷ the whole (all units).",
      "format": "money"
    },
    "each": {
      "label": "Each party",
      "description": "Each party’s share of the amount and percent, in the order typed.",
      "format": "text"
    },
    "summary": {
      "label": "Answer",
      "description": "The answer in one sentence.",
      "format": "text"
    }
  },
  "defaultAnswer": {
    "inputs": {
      "mode": "share",
      "amt": 60000,
      "part": 24,
      "whole": 40,
      "parties": [
        {
          "units": 50
        },
        {
          "units": 30
        },
        {
          "units": 20
        }
      ]
    },
    "outputs": {
      "share": 36000,
      "percent": 60,
      "rest": 24000,
      "perUnit": 1500,
      "summary": "The pro rata amount is $36,000.00 of $60,000.00"
    },
    "text": "The pro rata amount is $36,000.00 of $60,000.00."
  },
  "examples": [
    {
      "given": {
        "mode": "share",
        "amt": 60000,
        "part": 24,
        "whole": 40
      },
      "expect": {
        "share": 36000,
        "percent": 60,
        "rest": 24000,
        "perUnit": 1500
      },
      "source": "IRS, Instructions for Form 1120-S, Shareholder’s Pro Rata Share Items, General Rule (each shareholder’s pro rata share is determined by the number of shares of stock owned each day and the total shares outstanding each day), https://www.irs.gov/instructions/i1120s (retrieved 2026-10-02); hand calculation in content.mdx: 60,000 × 24 ÷ 40 = 36,000"
    },
    {
      "given": {
        "mode": "share",
        "amt": 1200,
        "part": 73,
        "whole": 365
      },
      "expect": {
        "share": 240,
        "percent": 20,
        "summary": "The pro rata amount is $240.00 of $1,200.00"
      },
      "source": "IRS, Instructions for Form 1120-S, Shareholder’s Pro Rata Share Items, General Rule (each shareholder’s pro rata share is determined by the number of shares of stock owned each day and the total shares outstanding each day), https://www.irs.gov/instructions/i1120s (retrieved 2026-10-02); hand calculation in content.mdx: 1,200 × 73 ÷ 365 = 240"
    },
    {
      "given": {
        "mode": "split",
        "amt": 10000,
        "parties": [
          {
            "units": 50
          },
          {
            "units": 30
          },
          {
            "units": 20
          }
        ]
      },
      "expect": {
        "share": 5000,
        "each": "Party 1: $5,000.00 (50%); Party 2: $3,000.00 (30%); Party 3: $2,000.00 (20%)"
      },
      "source": "IRS, Instructions for Form 1120-S, Shareholder’s Pro Rata Share Items, General Rule (each shareholder’s pro rata share is determined by the number of shares of stock owned each day and the total shares outstanding each day), https://www.irs.gov/instructions/i1120s (retrieved 2026-10-02); hand calculation in content.mdx: 10,000 × 50 ÷ 100, × 30 ÷ 100, × 20 ÷ 100"
    },
    {
      "given": {
        "mode": "split",
        "amt": 100,
        "parties": [
          {
            "units": 1
          },
          {
            "units": 1
          },
          {
            "units": 1
          }
        ]
      },
      "expect": {
        "share": 33.333333333333336,
        "each": "Party 1: $33.33 (33.33%); Party 2: $33.33 (33.33%); Party 3: $33.33 (33.33%)"
      },
      "source": "IRS, Instructions for Form 1120-S, Shareholder’s Pro Rata Share Items, General Rule (each shareholder’s pro rata share is determined by the number of shares of stock owned each day and the total shares outstanding each day), https://www.irs.gov/instructions/i1120s (retrieved 2026-10-02); hand calculation in content.mdx: 100 ÷ 3 = 33.33 each, rounded to the cent; Python 3: 100*1/3"
    }
  ],
  "sources": [
    "IRS, Instructions for Form 1120-S (2025), Schedules K and K-1, Shareholder’s Pro Rata Share Items, General Rule (each shareholder’s pro rata share of items is determined by the number of shares of stock owned each day during the tax year and the total number of shares outstanding each day). https://www.irs.gov/instructions/i1120s (retrieved 2026-10-02)"
  ],
  "related": [
    "prorated-rent",
    "percentage",
    "salary"
  ],
  "changelog": []
}