Days worked per period

There are different techniques for managing employees' working hours.

For different scenarios see Work limits.

This guide shows you how to manage employees' hours with days worked per period. A period can be defined as a week, month, or the entire schedule.

Prerequisites

To run the examples in this guide, you need to authenticate with a valid API key for the Employee Shift Scheduling model:

  1. Log in to Timefold Platform: app.timefold.ai

  2. From the Dashboard, click your tenant, and from the drop-down menu select Tenant Settings, then choose API Keys.

  3. Create a new API key or use an existing one. Ensure the list of models for the API key contains the Employee Shift Scheduling model.

In the examples, replace <API_KEY> with the API Key you just copied.

1. Define days worked per period rules

Period rules are defined in contracts:

{
  "contracts": [
    {
      "id": "partTimeContract",
      "periodRules": [
        {
          "id": "Max4DaysPerWeek",
          "period": "WEEK",
          "daysWorkedMax": 4,
          "satisfiability": "REQUIRED"
        }
      ]
    }
  ]
}

Period rules can define how many days employees work in a given period. For instance, a maximum of 4 days per week.

PeriodRules must include an ID.

period sets the period the rule applies to, for instance, DAY, WEEK, MONTH, SCHEDULE.

Further information about period:

DAY spans a single day and occurs every day in the schedule.

WEEK spans 7 days and occurs every week (including partial weeks) in the schedule. The default start of the week is Monday, but this can be overridden to any day in the week:

{
  "scheduleParameterization": {
    "weekStart": "THURSDAY"
  }
}

MONTH spans the entire month. MONTH has a variable number of days depending on the days in the month and occurs every month (including partial months) in the schedule.

SCHEDULE spans the entire schedule.

You can define custom periods to apply to this rule in the following way: 
{
  "scheduleParameterization": {
    "periods": [
      {
        "id": "PAY_PERIOD",
        "dateSpans": [
          {
            "start": "2023-01-01",
            "end": "2023-01-15"
          }
        ]
      }
    ]
  }
}

The start and end dates are inclusive.

daysWorkedMax sets the maximum number of days the employee can work in the specified period.

periodRules can include or exclude shifts based on shift tags.

{
  "periodRules": [
    {
      "id": "partTimeContract",
      "periodRules": [
        {
          "id": "Max4DaysPerWeek",
          "period": "WEEK",
          "daysWorkedMax": 4,
          "satisfiability": "REQUIRED",
          "includeShiftTags": ["Part-time"],
          "shiftTagMatches": "ALL"
        }
      ]
    }
  ]
}
Further information about including or excluding shifts with shift tags:

Shifts with specific tags can be included or excluded by the rule. Tags are defined in shifts:

{
  "shifts": [
    {
      "id": "2027-02-01",
      "start": "2027-02-01T09:00:00Z",
      "end": "2027-02-01T17:00:00Z",
      "tags": ["Part-time"]
    }
  ]
}

Use includeShiftTags to include shifts with specific tags or excludeShiftTags to exclude shifts with specific tags.

shiftTagMatches can be set to ALL or ANY. The default behavior for shiftTagMatches is ALL, and if omitted, the default ALL will be used.

The rule can define either includeShiftTags or excludeShiftTags, but not both.

{
  "includeShiftTags": ["Part-time", "Weekend"],
  "shiftTagMatches": "ALL"
}

With shiftTagMatches set to ALL, all tags defined by the rule’s includeShiftTags attribute must be present in the shift. With shiftTagMatches set to ANY, at least one tag defined by the rule’s includeShiftTags attribute must be present in the shift.

{
  "excludeShiftTags": ["Part-time", "Weekend"],
  "shiftTagMatches": "ALL"
}

With shiftTagMatches set to ALL, all tags defined by the rule’s excludeShiftTags attribute cannot be present in the shift. This is useful when you want to exclude things in combination with each other. For instance, excluding the shift tags Part-time and Weekend with shiftTagMatches set to All, will exclude shifts that include the tags Part-time and Weekend from the rule. Shifts tagged only Part-time or only Weekend will not be excluded.

With shiftTagMatches set to ANY, any of the tags defined by the rule’s excludeShiftTags attribute cannot be present in the shift. This is useful when you need to exclude tags regardless of their relationship to other tags. For instance, excluding the shift tags Part-time and Weekend with shiftTagMatches set to ANY, will exclude any shift that includes the tags Part-time or Weekend, whether they occur together or not.

Each employee must specify which contracts apply to them:

{
  "employees": [
    {
      "id": "Ann",
      "contracts": [
        "partTimeContract"
      ]
    }
  ]
}

The satisfiability of the rule can be REQUIRED or PREFERRED. REQUIRED is the default if omitted.

2. Required days worked per period

When the satisfiability of the rule is REQUIRED, the Days worked per period not in required range for employee hard constraint is invoked, which makes sure the number of days worked does not exceed the limit specified in daysWorkedMax.

Shifts will be left unassigned if assigning them would break the Days worked per period not in required range for employee constraint.

In the following example, Ann and Beth both have contracts with a required maximum of 4 days per week. There are 5 shifts on 5 days. Ann is assigned 4 shifts and Beth is assigned 1 shift.

required days worked per period

  • Input

  • Output

Try this example in Timefold Platform by saving this JSON into a file called sample.json and make the following API call: 
curl -X POST -H "Content-type: application/json" -H 'X-API-KEY: <API_KEY>' https://app.timefold.ai/api/models/employee-scheduling/v1/schedules [email protected]
{
  "config": {
    "run": {
      "name": "Required days worked per period example"
    }
  },
  "modelInput": {
    "contracts": [
      {
        "id": "partTimeContract",
        "periodRules": [
          {
            "id": "Max4DaysPerWeek",
            "period": "WEEK",
            "satisfiability": "REQUIRED",
            "daysWorkedMax": 4
          }
        ]
      }
    ],
    "employees": [
      {
        "id": "Ann",
        "contracts": [
          "partTimeContract"
        ]
      },
      {
        "id": "Beth",
        "contracts": [
          "partTimeContract"
        ]
      }
    ],
    "shifts": [
      {
        "id": "Mon",
        "start": "2027-02-01T09:00:00Z",
        "end": "2027-02-01T17:00:00Z"
      },
      {
        "id": "Tue",
        "start": "2027-02-02T09:00:00Z",
        "end": "2027-02-02T17:00:00Z"
      },
      {
        "id": "Wed",
        "start": "2027-02-03T09:00:00Z",
        "end": "2027-02-03T17:00:00Z"
      },
      {
        "id": "Thu",
        "start": "2027-02-04T09:00:00Z",
        "end": "2027-02-04T17:00:00Z"
      },
      {
        "id": "Fri",
        "start": "2027-02-05T09:00:00Z",
        "end": "2027-02-05T17:00:00Z"
      }
    ]
  }
}
To request the solution, locate the 'ID' from the response to the post operation and append it to the following API call: 
curl -X GET -H 'X-API-KEY: <API_KEY>' https://app.timefold.ai/api/models/employee-scheduling/v1/schedules/<ID>
{
  "run": {
    "id": "ID",
    "name": "Required days worked per period example",
    "submitDateTime": "2025-05-23T07:02:32.406962234Z",
    "startDateTime": "2025-05-23T07:02:44.102043218Z",
    "activeDateTime": "2025-05-23T07:02:44.295623181Z",
    "completeDateTime": "2025-05-23T07:03:15.319768267Z",
    "shutdownDateTime": "2025-05-23T07:03:15.624579247Z",
    "solverStatus": "SOLVING_COMPLETED",
    "score": "0hard/0medium/0soft",
    "tags": [
      "system.profile:default"
    ],
    "validationResult": {
      "summary": "OK"
    }
  },
  "modelOutput": {
    "shifts": [
      {
        "id": "Mon",
        "employee": "Ann"
      },
      {
        "id": "Tue",
        "employee": "Ann"
      },
      {
        "id": "Wed",
        "employee": "Ann"
      },
      {
        "id": "Thu",
        "employee": "Ann"
      },
      {
        "id": "Fri",
        "employee": "Beth"
      }
    ]
  },
  "inputMetrics": {
    "employees": 2,
    "shifts": 5,
    "pinnedShifts": 0
  },
  "kpis": {
    "assignedShifts": 5,
    "unassignedShifts": 0,
    "disruptionPercentage": 0.0,
    "activatedEmployees": 2,
    "assignedMandatoryShifts": 5,
    "assignedOptionalShifts": 0,
    "travelDistance": 0
  }
}

modelOutput contains the schedule with Ann assigned 4 shifts and Beth assigned 1 shift.

inputMetrics provides a breakdown of the inputs in the input dataset.

KPIs provides the KPIs for the output including:

    "assignedShifts": 5,
    "activatedEmployees": 2,
    "assignedMandatoryShifts": 5

3. Preferred days worked per period

When the satisfiability of the rule is PREFERRED, the Days worked per period not in preferred range for employee soft constraint is invoked.

With a satisfiability of PREFERRED a daysWorkedMin value can also be provided to set the preferred minimum number of days worked.

{
  "contracts": [
    {
      "id": "partTimeContract",
      "periodRules": [
        {
          "id": "Min2DaysMax4DaysPerWeek",
          "satisfiability": "PREFERRED",
          "period": "WEEK",
          "daysWorkedMin": 2,
          "daysWorkedMax": 4
        }
      ]
    }
  ]
}

This constraint adds a soft penalty to the run score when the number of assigned days is below the limit defined by daysWorkedMin or above the limit defined by daysWorkedMax, incentivizing Timefold to find an alternative solution.

In the following example, Ann and Beth both have contracts with a preferred minimum of 2 days and a preferred maximum of 4 days per week. There are 5 shifts on 5 days. Beth is assigned 2 shift and Ann is assigned 3 shifts.

preferred days worked per period

  • Input

  • Output

Try this example in Timefold Platform by saving this JSON into a file called sample.json and make the following API call: 
curl -X POST -H "Content-type: application/json" -H 'X-API-KEY: <API_KEY>' https://app.timefold.ai/api/models/employee-scheduling/v1/schedules [email protected]
{
  "config": {
    "run": {
      "name": "Preferred days worked per period example"
    }
  },
  "modelInput": {
    "contracts": [
      {
        "id": "partTimeContract",
        "periodRules": [
          {
            "id": "Min2DaysMax4DaysPerWeek",
            "period": "WEEK",
            "satisfiability": "PREFERRED",
            "daysWorkedMin": 2,
            "daysWorkedMax": 4
          }
        ]
      }
    ],
    "employees": [
      {
        "id": "Ann",
        "contracts": [
          "partTimeContract"
        ]
      },
      {
        "id": "Beth",
        "contracts": [
          "partTimeContract"
        ]
      }
    ],
    "shifts": [
      {
        "id": "Mon",
        "start": "2027-02-01T09:00:00Z",
        "end": "2027-02-01T17:00:00Z"
      },
      {
        "id": "Tue",
        "start": "2027-02-02T09:00:00Z",
        "end": "2027-02-02T17:00:00Z"
      },
      {
        "id": "Wed",
        "start": "2027-02-03T09:00:00Z",
        "end": "2027-02-03T17:00:00Z"
      },
      {
        "id": "Thu",
        "start": "2027-02-04T09:00:00Z",
        "end": "2027-02-04T17:00:00Z"
      },
      {
        "id": "Fri",
        "start": "2027-02-05T09:00:00Z",
        "end": "2027-02-05T17:00:00Z"
      }
    ]
  }
}
To request the solution, locate the 'ID' from the response to the post operation and append it to the following API call: 
curl -X GET -H 'X-API-KEY: <API_KEY>' https://app.timefold.ai/api/models/employee-scheduling/v1/schedules/<ID>
{
  "run": {
    "id": "ID",
    "name": "Preferred days worked per period example",
    "submitDateTime": "2025-03-31T08:15:18.068850927Z",
    "startDateTime": "2025-03-31T08:15:28.940042351Z",
    "activeDateTime": "2025-03-31T08:15:29.019242953Z",
    "completeDateTime": "2025-03-31T08:20:30.167581606Z",
    "shutdownDateTime": "2025-03-31T08:20:30.330498606Z",
    "solverStatus": "SOLVING_COMPLETED",
    "score": "0hard/0medium/0soft",
    "tags": [
      "system.profile:default"
    ],
    "validationResult": {
      "summary": "OK"
    }
  },
  "modelOutput": {
    "shifts": [
      {
        "id": "Mon",
        "employee": "Ann"
      },
      {
        "id": "Tue",
        "employee": "Ann"
      },
      {
        "id": "Wed",
        "employee": "Beth"
      },
      {
        "id": "Thu",
        "employee": "Ann"
      },
      {
        "id": "Fri",
        "employee": "Beth"
      }
    ]
  },
  "inputMetrics": {
    "employees": 2,
    "shifts": 5,
    "pinnedShifts": 0
  },
  "kpis": {
    "assignedShifts": 5,
    "unassignedShifts": 0,
    "workingTimeFairnessPercentage": null,
    "disruptionPercentage": 0.0,
    "averageDurationOfEmployeesPreferencesMet": null,
    "minimumDurationOfPreferencesMetAcrossEmployees": null,
    "averageDurationOfEmployeesUnpreferencesViolated": null,
    "maximumDurationOfUnpreferencesViolatedAcrossEmployees": null,
    "activatedEmployees": 2,
    "assignedMandatoryShifts": 5,
    "assignedOptionalShifts": 0,
    "travelDistance": 0
  }
}

modelOutput contains the schedule with Ann and Beth assigned to shifts on days within the range of 2 to 4 days per week.

inputMetrics provides a breakdown of the inputs in the input dataset.

KPIs provides the KPIs for the output including:

{
  "assignedShifts": 5,
  "unassignedShifts": 0,
  "activatedEmployees": 2,
  "assignedMandatoryShifts": 5
}

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