---
title: "Use the PRORATA Function to Calculate Prorata Days per Period"
slug: "prorata-function"
description: "Learn to use the PRORATA function to calculate the number of prorata days per period in a time range, based on start and end dates."
updated: 2025-10-27T17:17:06Z
published: 2025-10-30T09:30:13Z
canonical: "kb.pigment.com/prorata-function"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://kb.pigment.com/llms.txt
> Use this file to discover all available pages before exploring further.

# PRORATA function

## Description

Returns the prorata of days over time Dimensions. It can be used to calculate, for example, the **Full Time Equivalent (FTE)** of Employees by knowing their start and end date.

## Syntax

```plaintext
PRORATA(Time Dimension [, Start Date] [, End Date] [, Working Days] [, Holidays])
```

- `Time Dimension` based on the calendar settings, options are: `Day`, `Week`, `Month`, `Quarter`, `Half`, `Year`

- `Start Date` is **included**
- `End Date` is **excluded**

- `Working Days` defines which days of the week are working and non-working days. User must use a Metric of the Dimension `Day of Week` ⇒ `boolean`.
- `Holidays` defines which dates are holidays. User must use a Metric of the Dimension`Day`⇒ `boolean`

## Return type

`Number`

## Examples

| **Case** | **Results** | **Return Type** |
| --- | --- | --- |
| `PRORATA(month)` | returns `1` for each month | `Number` |
| `PRORATA(month, DATE(2020,6,1))` | returns `1` for each month, starting the 1st of June 2020, blank prior to that date | `Number` |
| `PRORATA(month, DATE(2020,6,15), DATE(2020,7,14))` | returns the prorata of days over June 2020 (16/30) and July 2020 (13/31). | `Number` |
| `PRORATA(month, 'employee'.'start date', 'employee'.'end date'+1)` | returns the monthly FTE (full time equivalent) by employee taking into account their start (included) and end date (included). | `Number` |
| `PRORATA(month, STARTOFMONTH('employee'.'start date'), STARTOFMONTH('employee'.'end date'+ 1))` | returns the monthly Headcount by employee (1 if the employee is present on the last day of each month) | `Number` |

**Excel equivalent**: None

**See also**: [DAYSINPERIOD](/v1/docs/daysinperiod-function), [STARTOFMONTH](/v1/docs/startofmonth-function)