---
url: >-
  /statelake/scripting-reference/functions-and-procedures/datetime-functions/yearspan.md
---

# YearSpan

The **YearSpan** function returns the approximate number of years between two specified **TDateTime** values, including any fraction of a year.

Because years are not all the same length due to leap years, **YearSpan** returns an approximation based on an assumption of 365.25 days per year.

But unlike the similar function **YearsBetween**, the **YearSpan** function reports incomplete years as a fraction of the 365.25-day year.

The ordering of the two dates doesn't matter - the number of years will not be negative.

**Declaration**: function YearSpan(const ANow, AThen: TDateTime): Double;

The following example shows several scenarios.

```pascal
procedure OnMapEvent(var Value:Variant);
var
  vYearT, vDate : TDateTime;
  vStrYear, vStrDate : string;
  vBetwix : double;
begin
 //Result is 0.0848733744010951 of a year - run-date to run-date plus 1 month
 //Where run-date is 03-12-2023 plus 31 days (31/365.25 = 0.0848733744010951)
  vBetwix := YearSpan(Date, IncMonth(Date, 1));
  LogInfo(FloatToStr(vBetwix));

 //Result is 0.501026694045175 of a year - 6 months only or 183 days
  vStrDate := '01-10-2023';
  vStrYear := '01-04-2024';
  vDate := StringToDateTime('dd/mm/yyyy',vStrDate);
  vYearT := StringToDateTime('dd/mm/yyyy',vStrYear);
  vBetwix := YearSpan(vDate, vYearT);
  LogInfo(FloatToStr(vBetwix));

 //Result is 0.996577686516085 of a year - 2023 is NOT a leap year = 364 days
  vStrDate := '01-01-2023';
  vStrYear := '31-12-2023';
  vDate := StringToDateTime('dd/mm/yyyy',vStrDate);
  vYearT := StringToDateTime('dd/mm/yyyy',vStrYear);
  vBetwix := YearSpan(vDate, vYearT);
  LogInfo(FloatToStr(vBetwix));

 //Result is 0.999315537303217 of a year - 2024 is a leap year = 365 days
  vStrDate := '01-01-2024';
  vStrYear := '31-12-2024';
  vDate := StringToDateTime('dd/mm/yyyy',vStrDate);
  vYearT := StringToDateTime('dd/mm/yyyy',vStrYear);
  vBetwix := YearSpan(vDate, vYearT);
  LogInfo(FloatToStr(vBetwix));

 //Result is 1.00205338809035 of a year - whole leap year - 366 days
  vStrDate := '01-01-2024';
  vStrYear := '01-01-2025';
  vDate := StringToDateTime('dd/mm/yyyy',vStrDate);
  vYearT := StringToDateTime('dd/mm/yyyy',vStrYear);
  vBetwix := YearSpan(vDate, vYearT);
  LogInfo(FloatToStr(vBetwix));

 //Result is 1.00205338809035 of a year - whole year +1 - 366 days
  vStrDate := '01-01-2023';
  vStrYear := '02-01-2024';
  vDate := StringToDateTime('dd/mm/yyyy',vStrDate);
  vYearT := StringToDateTime('dd/mm/yyyy',vStrYear);
  vBetwix := YearSpan(vDate, vYearT);
  LogInfo(FloatToStr(vBetwix));

 //Result is 4 whole years - 1461 days
  vStrDate := '01-01-2023';
  vStrYear := '01-01-2027';
  vDate := StringToDateTime('dd/mm/yyyy',vStrDate);
  vYearT := StringToDateTime('dd/mm/yyyy',vStrYear);
  vBetwix := YearSpan(vDate, vYearT);
  LogInfo(FloatToStr(vBetwix));
  LogInfo('');

end;
```