Days off per period

There are different techniques for managing employees' time off.

This guide shows you how to include days off per period. Days off per period can be specified per week, month, or the entire schedule.

Prerequisites

Learn how to configure an API Key to run the examples in this guide:

Log in to Timefold Platform: app.timefold.ai
From the Dashboard, click your tenant, and from the drop-down menu select Tenant Settings, then choose API Keys.
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 off per period

Period rules are configured in contracts:

{
  "contracts": [
    {
      "id": "fullTimeContract",
      "periodRules": [
        {
          "id": "min2DaysOff",
          "period": "WEEK",
          "daysOffLimit":
          {
            "daysOffMin": 2
          },
          "satisfiability": "REQUIRED"
        }
      ]
    }
  ]
}

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.

Learn about counting days in period rules:

By default, period rules count shifts within the defined period if the shift starts within the defined period. For instance, if you define a rule that an employee can only work 1 shift a day, a night shift that started on the previous day but ends the following morning will not be counted and another shift might be assigned on the same day as the night shift ended.

To change this behavior change the field periodShiftOverlapKind from START_ONLY to START_AND_END.

{
  "periodRules": [
    {
      "id": "Max8HoursPerDayFullTime",
      "period": "DAY",
      "minutesWorkedMax": 480,
      "satisfiability": "REQUIRED",
      "periodShiftOverlapKind": "START_AND_END"
    }
}

The daysOffLimit object must include daysOffMin with the minimum number of days off.

You can optionally use includeDays to specify the days of the week that count toward the total. If includeDays is not included, all days count toward the total.

To create a rule that only counts weekdays and excludes weekends:

{
  "contracts": [
    {
      "id": "fullTimeContract",
      "periodRules": [
        {
          "id": "min2DaysOff",
          "period": "WEEK",
          "daysOffLimit":
          {
            "daysOffMin": 2,
            "includeDays": ["MONDAY", "TUESDAY", "WEDNESDAY", "THURSDAY", "FRIDAY"]
          },
          "satisfiability": "REQUIRED"
        }
      ]
    }
  ]
}

Each employee must specify which contracts apply to them:

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

periodRules can include or exclude shifts based on shift tags.

{
  "contracts": [
    {
      "id": "fullTimeContract",
      "periodRules": [
        {
          "id": "min2DaysOff",
          "period": "WEEK",
          "daysOffLimit":
          {
            "daysOffMin": 2
          },
          "includeShiftTags": ["Part-time"],
          "shiftTagMatches": "ALL",
          "satisfiability": "REQUIRED"
        }
      ]
    }
  ]
}

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.

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

2. Required days off per period

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

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

In the following example, there are 7 shifts, but Ann’s contract has a daysOffMin of 2. She is assigned 5 shifts, 2 shifts are left unassigned, and Ann has 2 days off.

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 off per period example"
    }
  },
  "modelInput": {
    "contracts": [
      {
        "id": "fullTimeContract",
        "periodRules": [
          {
            "id": "min2DaysOff",
            "period": "WEEK",
            "daysOffLimit":
            {
              "daysOffMin": 2
            },
            "satisfiability": "REQUIRED"
          }
        ]
      }
    ],
    "employees": [
      {
        "id": "Ann",
        "contracts": [
          "fullTimeContract"
        ]
      }
    ],
    "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"
      },
      {
        "id": "Sat",
        "start": "2027-02-06T09:00:00Z",
        "end": "2027-02-06T17:00:00Z"
      },
      {
        "id": "Sun",
        "start": "2027-02-07T09:00:00Z",
        "end": "2027-02-07T17:00:00Z"
      }
    ]
  }
}

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 off per period example",
    "submitDateTime": "2025-05-15T04:12:48.841418699Z",
    "startDateTime": "2025-05-15T04:13:06.647742868Z",
    "activeDateTime": "2025-05-15T04:13:06.879503897Z",
    "completeDateTime": "2025-05-15T04:13:37.675762988Z",
    "shutdownDateTime": "2025-05-15T04:13:37.960206521Z",
    "solverStatus": "SOLVING_COMPLETED",
    "score": "0hard/-2medium/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": "Ann"
      },
      {
        "id": "Sat",
        "employee": null
      },
      {
        "id": "Sun",
        "employee": null
      }
    ]
  },
  "inputMetrics": {
    "employees": 1,
    "shifts": 7,
    "pinnedShifts": 0
  },
  "kpis": {
    "assignedShifts": 5,
    "unassignedShifts": 2,
    "workingTimeFairnessPercentage": null,
    "disruptionPercentage": 0.0,
    "averageDurationOfEmployeesPreferencesMet": null,
    "minimumDurationOfPreferencesMetAcrossEmployees": null,
    "averageDurationOfEmployeesUnpreferencesViolated": null,
    "maximumDurationOfUnpreferencesViolatedAcrossEmployees": null,
    "activatedEmployees": 1,
    "assignedMandatoryShifts": 5,
    "assignedOptionalShifts": 0,
    "assignedShiftGroups": null,
    "unassignedShiftGroups": null,
    "travelDistance": 0
  }
}

modelOutput contains the schedule with Ann not being assigned shifts on 2 days of the week.

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

KPIs provides the KPIs for the output including:

{
  "assignedShifts": 5,
  "unassignedShifts": 2,
  "activatedEmployees": 1,
  "assignedMandatoryShifts": 5
}

3. Preferred days off per period

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

By default, every constraint has a weight of 1, meaning that all constraints are equally important.

Learn about changing the weight of this constraint:

Use the constraint configuration’s daysOffPerPeriodNotInPreferredRangeForEmployeeWeight attribute to update the weight of the constraint. 0 disables the constraint. A constraint weight of 10, means the constraint is 10 times more important than a constraint with a weight of 1.

"overrides": { "daysOffPerPeriodNotInPreferredRangeForEmployeeWeight": 10 }

With PREFERRED satisfiability you can also use daysOffMax to specify the maximum number of days off.

{
  "contracts": [
    {
      "id": "fullTimeContract",
      "periodRules": [
        {
          "id": "min2DaysOff",
          "period": "WEEK",
          "daysOffLimit":
          {
            "daysOffMin": 1,
            "daysOffMax": 3
          },
          "satisfiability": "PREFERRED"
        }
      ]
    }
  ]
}

This constraint adds a soft penalty if the number of days off is below the limit set in daysoffMin or above the limit set in daysOffMax.

Timefold is incentivized to use the solution with the best score.

This rule is more likely to be satisfied for employees with a higher employee priority.

In the following example, there are 7 shifts, but Ann’s contract has a daysOffMin of 1 and a daysOffMax of 3. She is assigned all 7 shifts, and a soft penalty is applied to the run score.

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 off per period example"
    }
  },
  "modelInput": {
    "contracts": [
      {
        "id": "fullTimeContract",
        "periodRules": [
          {
            "id": "min2DaysOff",
            "period": "WEEK",
            "daysOffLimit":
            {
              "daysOffMin": 1,
              "daysOffMax": 3
            },
            "satisfiability": "PREFERRED"
          }
        ]
      }
    ],
    "employees": [
      {
        "id": "Ann",
        "contracts": [
          "fullTimeContract"
        ]
      }
    ],
    "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"
      },
      {
        "id": "Sat",
        "start": "2027-02-06T09:00:00Z",
        "end": "2027-02-06T17:00:00Z"
      },
      {
        "id": "Sun",
        "start": "2027-02-07T09:00:00Z",
        "end": "2027-02-07T17:00:00Z"
      }
    ]
  }
}

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 off per period example",
    "submitDateTime": "2025-05-15T09:43:13.255755752Z",
    "startDateTime": "2025-05-15T09:43:25.755410242Z",
    "activeDateTime": "2025-05-15T09:43:25.932572105Z",
    "completeDateTime": "2025-05-15T09:43:56.770085733Z",
    "shutdownDateTime": "2025-05-15T09:43:57.086570792Z",
    "solverStatus": "SOLVING_COMPLETED",
    "score": "0hard/0medium/-960soft",
    "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": "Ann"
      },
      {
        "id": "Sat",
        "employee": "Ann"
      },
      {
        "id": "Sun",
        "employee": "Ann"
      }
    ]
  },
  "inputMetrics": {
    "employees": 1,
    "shifts": 7,
    "pinnedShifts": 0
  },
  "kpis": {
    "assignedShifts": 7,
    "unassignedShifts": 0,
    "workingTimeFairnessPercentage": null,
    "disruptionPercentage": 0.0,
    "averageDurationOfEmployeesPreferencesMet": null,
    "minimumDurationOfPreferencesMetAcrossEmployees": null,
    "averageDurationOfEmployeesUnpreferencesViolated": null,
    "maximumDurationOfUnpreferencesViolatedAcrossEmployees": null,
    "activatedEmployees": 1,
    "assignedMandatoryShifts": 7,
    "assignedOptionalShifts": 0,
    "assignedShiftGroups": null,
    "unassignedShiftGroups": null,
    "travelDistance": 0
  }
}

modelOutput contains the schedule with all 7 shifts assigned.

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

KPIs provides the KPIs for the output including:

{
  "assignedShifts": 7,
  "activatedEmployees": 1,
  "assignedMandatoryShifts": 7
}

See the full API spec or try the online API.
Learn more about employee shift scheduling from our YouTube playlist.
See other options for managing employees' Time off.

Days off per period

Prerequisites

1. Define days off per period

2. Required days off per period

3. Preferred days off per period

Next