如何根据任务起止日期与TODAY()函数计算任务预期完成百分比？

Hey there, let's break down exactly how to calculate the expected completion percentage for a task using its start date, end date, and the TODAY() function. This is a super common need for project trackers or spreadsheets, so I'll cover all the key scenarios and edge cases to make sure you've got it right.

Core Variables First #

Let's define the values we're working with to keep things clear:

• Start_Date: The official start date of your task
• End_Date: The scheduled end date of your task
• Today_Date: The current date, pulled dynamically via the TODAY() function

Scenario 1: Task hasn't started yet #

If today's date is before the task's start date, the task hasn't begun—so completion percentage is 0%.
The check for this looks like:

IF(TODAY() < Start_Date, 0, ...)

Scenario 2: Task is already completed #

If today's date is on or after the task's end date, the task should be fully done—so completion percentage is 100%.
The check here is:

IF(TODAY() >= End_Date, 100, ...)

Scenario 3: Task is in progress (active period) #

This is the core calculation. We need to find what percentage of the total task duration has passed as of today.

Key Note About Date Math #

When you subtract dates (e.g., End_Date - Start_Date), you get the number of days between those dates—not the total number of days the task spans. To fix this, we add 1 to include both the start and end dates in the count.

The formula for in-progress completion is:

ROUND(((TODAY() - Start_Date + 1) / (End_Date - Start_Date + 1)) * 100, 2)

• TODAY() - Start_Date + 1: Number of days completed so far (including today)
• End_Date - Start_Date + 1: Total scheduled days for the task
• Multiply by 100 to get a percentage, use ROUND() to keep it clean (2 decimal places here)

Full Combined Formula #

Putting all scenarios together (plus a check for invalid date ranges, like start date being later than end date):

=IF(Start_Date > End_Date, "Invalid Date Range", 
    IF(TODAY() < Start_Date, 0, 
        IF(TODAY() >= End_Date, 100, 
            ROUND(((TODAY() - Start_Date + 1) / (End_Date - Start_Date + 1)) * 100, 2)
        )
    )
)

Quick Examples to Verify #

Let's test with real dates to make it concrete:

• Example 1: Start=2024-05-01, End=2024-05-10, Today=2024-05-03
  Total days: 10-1+1=10 | Days completed:3-1+1=3 | Completion: (3/10)*100 = 30%
• Example 2: Today=2024-04-28 (before start date) → 0%
• Example 3: Today=2024-05-15 (after end date) → 100%

内容的提问来源于stack exchange，提问作者Carlos Andres Alape Mahecha