Enter the total delay time (ms,s,min) and the total overall time (ms,s,min) into the Delay Percentage Calculator. The calculator will evaluate the Delay Percentage.
Delay Percentage Formula
The calculator uses one of three formulas depending on the tab you select.
Delay time mode:
Delay % = (Delay time / Total time) × 100
Plan vs actual mode:
Delay % = ((Actual duration − Planned duration) / Planned duration) × 100
Tasks mode:
Delay % = (Delayed tasks / Total tasks) × 100
- Delay time — total time lost to delays.
- Total time — full window the delay is measured against.
- Planned duration — scheduled or expected time to complete the work.
- Actual duration — time the work actually took.
- Delayed tasks — tasks that finished late.
- Total tasks — every task in scope, late or on time.
Delay time and total time must use the same unit before dividing. The calculator converts units automatically. In plan vs actual mode, a negative result means the work finished early. Task counts must be whole numbers.
Reference Tables
Use these to interpret the percentage the calculator returns.
| Delay % | Status | Typical reading |
|---|---|---|
| 0% | On time | No measurable delay. |
| 0.1% – 5% | Low | Within normal variance. |
| 5% – 15% | Moderate | Worth investigating the cause. |
| > 15% | High | Schedule or process likely needs revision. |
| Negative | Ahead | Plan vs actual only — finished before plan. |
| Unit | Equals (seconds) |
|---|---|
| 1 millisecond | 0.001 |
| 1 second | 1 |
| 1 minute | 60 |
| 1 hour | 3,600 |
| 1 day | 86,400 |
Worked Examples
Delay time: A flight loses 12 minutes over a 120 minute trip. 12 ÷ 120 × 100 = 10% delay.
Plan vs actual: A task planned for 8 hours takes 9.5 hours. (9.5 − 8) ÷ 8 × 100 = 18.75% overrun.
Tasks: 6 of 40 tasks finish late. 6 ÷ 40 × 100 = 15% delayed.
Can the result be more than 100%? Only in plan vs actual mode. If actual duration is double the plan, the delay percentage is 100%. Delay time and tasks modes are capped at 100% because the part cannot exceed the whole.
What if there is no delay? The result is 0%. In plan vs actual mode, a negative result means the work finished ahead of schedule.
