# Documentation/Calc Functions/YEARFRAC

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## Function name:

YEARFRAC

## Category:

Date and Time

## Summary:

The result is the number of the years (including fractional part) between **StartDate** and **EndDate**.

## Syntax:

YEARFRAC(**StartDate**; **EndDate**; **Basis**)

## Returns:

## Arguments:

**StartDate** and **EndDate** are two date values.

**Basis** (optional) is chosen from a list of options and indicates how the year is to be calculated.

Basis | Calculation |
---|---|

0 or missing | US method (NASD), 12 months of 30 days each |

1 | Exact number of days in months, exact number of days in year |

2 | Exact number of days in month, year has 360 days |

3 | Exact number of days in month, year has 365 days |

4 | European method, 12 months of 30 days each |

## Additional details:

When entering dates as part of formulas, slashes or dashes used as date separators are interpreted as arithmetic operators. Therefore, dates entered in this format are not recognized as dates and result in erroneous calculations. To keep dates from being interpreted as parts of formulas use the DATE function, for example, DATE(1954;7;20), or place the date in quotation marks and use the ISO 8601 notation, for example, "1954-07-20". Avoid using locale dependent date formats such as "07/20/54", the calculation may produce errors if the document is loaded under different locale settings.

Unambiguous conversion is possible for ISO 8601 dates and times in their extended formats with separators. If a **#VALUE!** error occurs, then unselect **Generate #VALUE! error** in **Tools > Options > LibreOffice Calc > Formula**, button **Details...** in section "Detailed Calculation Settings", **Conversion from text to number** list box.

## Examples:

What fraction of the year 2008 lies between 2008-01-01 and 2008-07-01?

=YEARFRAC("2008-01-01"; "2008-07-01";0) returns 0.50.