The Duration Percentage Calculator shows how much of your planned time a task or project actually took. It gives you a percentage to see if you’re ahead, on time, or behind schedule. Plus, it can tell you the time difference and how efficient your plan was. This is great for real-life decisions, like adjusting deadlines, managing resources, or improving future plans.
This calculator keeps projects running smoothly by showing where time stands. It’s reliable for important choices, like meeting goals or staying within budget. Want to know how it’s calculated? Let’s check out the formula next.
Formula for Duration Percentage
The main formula is simple:
Duration Percentage = (Actual Duration / Planned Duration) × 100
Where:
- Duration Percentage = Percentage of planned time used
- Actual Duration = Time it really took (days, hours, etc.)
- Planned Duration = Time you set aside (days, hours, etc.)
Extra Formulas
For Schedule Variance (SV):
SV = Planned Duration – Actual Duration
- Positive SV = Ahead of schedule
- Negative SV = Behind schedule
For Schedule Performance Index (SPI):
SPI = Planned Duration / Actual Duration
- SPI > 1 = Ahead of schedule
- SPI = 1 = On schedule
- SPI < 1 = Behind schedule
These formulas come from project management basics. Use the same units—like days or hours—for both durations. Now, let’s make it easier with a table.
Quick Reference Table for Duration Percentage
Why calculate every time? This table shows common results and what they mean. It’s a fast way to check without math.
| Duration Percentage | SPI | Meaning |
|---|---|---|
| 80% | 1.25 | Ahead of schedule |
| 100% | 1.0 | Right on schedule |
| 120% | 0.83 | Behind schedule |
How to Use the Table
- Find your percentage or SPI.
- Check what it says about your timing.
- Use it to adjust your plan.
This table helps with searches like “what’s 120% duration mean.” For exact results, use the formula. Next, let’s try an example.
Example of Duration Percentage Calculator
Suppose you planned a task to take 10 days, but it took 8 days. You want to know the duration percentage, variance, and SPI. Here’s how to do it:
- Calculate Duration Percentage:
Duration Percentage = (8 / 10) × 100 = 80% - Find Schedule Variance:
SV = 10 – 8 = 2 days (ahead by 2 days) - Calculate SPI:
SPI = 10 / 8 = 1.25
So, the duration percentage is 80%, you’re 2 days ahead, and an SPI of 1.25 shows you beat the schedule. This matches project tracking standards.
Most Common FAQs
It shows if you’re sticking to your timeline—key for finishing on time.
Above 1 is good—it means you’re ahead; below 1 means you’re late.
Yes, just keep actual and planned units the same—like hours or weeks.