Length of Service Calculator

When you need length of service for length of service, Length of Service Calculator turns the relevant values into a clear answer. Enter Employment Start Date and As-of Date, and the calculator uses those values to show length of service. It helps with length of service when an exact date, duration, deadline or repeated schedule matters. Leap years can affect annual-date calculations, so use the leap-day convention explained on the page when comparing different years. Keeping the source values consistent makes it easier to compare different length of service options without changing the basis of the calculation. Read the worked example on the Length of Service Calculator page if you want to check how the entered values lead to length of service before using your own figures.

How to use Length of Service Calculator

To use Length of Service Calculator, start with the values that apply to your length of service case. Choose the required date for Employment Start Date, then choose the required date for As-of Date. Run the calculation to see length of service, then compare the answer with the values you entered before using it. If the date is 29 February, remember that non-leap years need the fallback date explained on the page. For a second scenario, keep the same units and assumptions and change only the inputs that genuinely differ. Keep any cost, delay, allowance or adjustment that is not represented by a field separate unless the page specifically tells you to include it. The worked example on the Length of Service Calculator page can help you confirm how the inputs should be entered before you calculate your own case.

Why use this tool?

Length of Service Calculator is useful when length of service involves dates or time periods that are easy to miscount manually. It gives you a consistent way to work out length of service from the dates or times you already know. This is especially helpful when comparing alternative dates, checking a deadline or planning around a fixed schedule. Because the calculation is based on Employment Start Date and As-of Date, you can see which values need to change when you want to test another case. Because Length of Service Calculator focuses only on length of service, you can change one input at a time and see how that affects length of service without changing the basis of the comparison.

How the calculation works

Length of Service Calculator calculates completed years, months and days of service between the employment start date and the as-of date. Employment Start Date and As-of Date provide the calendar dates used by the calculation. For a 29 February date in a non-leap year, the calculator uses the fallback date stated on the page so the annual date remains consistent. The result is reported as length of service, giving you a consistent basis for comparing dates or timings. For a second length of service case, use the same units and counting convention so the two results remain directly comparable.

Example

For example, enter Employment Start Date = 15 September 2026 and As-of Date = 20 October 2026. Using those inputs gives 0 years, 1 months, 5 days for length of service. This works by calculating completed years, months and days of service between the employment start date and the as-of date, which gives the displayed length of service.

Practical tip

For Length of Service Calculator, check Employment Start Date and As-of Date against the real calendar dates before calculating, especially when the answer affects a deadline or countdown. Keep the same units and assumptions whenever you compare two results from this tool. If two length of service scenarios are being compared, keep the same inclusion rule for start and end dates so length of service is comparable. For a second length of service case, keep the same units and conventions and change only the values that genuinely differ.