Calculate a construction completion date from a start date and contract duration in calendar or working days, with optional weather and closeout days.

Days and months must be whole numbers; weeks must produce a whole number of scheduled days. Months apply only to calendar schedules.

Optional settings
Blank means 0; uses the selected counting basis.

Optional. Requires a contract date; this arithmetic estimate does not determine liability.

Related Calculators

Construction Completion Date Formula

The following formula is used to calculate the construction completion date for a given start date and duration.

Dc = Ds + T – 1

Variables:

  • Dc is the construction completion date
  • Ds is the construction start date
  • T is the construction duration in days

For inclusive calendar-day counting, add the duration minus one day to the start date. Working schedules count only selected weekdays and add the entered lost-workday allowances. Closeout is added afterward in calendar days; contract counting rules may differ.

What is a Construction Completion Date?

The construction completion date is the date on which a construction project is expected to be finished. This date is crucial for project planning and scheduling, as it helps in coordinating various activities and ensuring that the project is completed on time. The completion date is often determined based on the start date of the construction and the estimated duration required to complete the project. Accurate calculation of the completion date is essential for managing resources, budgeting, and meeting contractual obligations.

How to Calculate Construction Completion Date?

The following steps outline how to calculate the Construction Completion Date.

  1. First, determine the construction start date (Ds).
  2. Next, determine the construction duration (T) in days.
  3. Finally, calculate the construction completion date using the formula Dc = Ds + T – 1.
  4. After inserting the values and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Construction start date (Ds) = 2023-01-01

Construction duration (T) = 100 inclusive calendar days; completion = 2023-04-10.