Calculator Inputs
Enter single-task and dual-task values for two activities. Choose whether higher or lower values indicate better performance.
Plotly graph
Reading the graph
The chart compares single-task and dual-task values for both activities. Higher dual-task bars for time-based metrics usually mean extra drag. Lower dual-task bars for accuracy-based metrics usually mean performance loss.
When the cost is negative, performance improved under overlap. That can happen with warm-up effects, easier trials, or measurement noise.
Formula used
For lower-is-better metrics: Dual-task cost = ((Dual - Single) / Single) × 100
For higher-is-better metrics: Dual-task cost = ((Single - Dual) / Single) × 100
Weighted overall cost: ((Cost A × Weight A) + (Cost B × Weight B)) / (Weight A + Weight B)
Weighted retention: a weighted average of task-level retention percentages.
Estimated lost minutes per session: Planned minutes × Overall cost + switch cost + shared overhead. The calculator treats negative cost as zero for lost-time estimation.
How to use this calculator
- Enter names for two competing tasks.
- Choose whether higher or lower numbers indicate better performance.
- Type single-task and dual-task values for each task.
- Set weights to reflect task importance.
- Add planned session minutes, repetitions, switch counts, and overhead.
- Submit the form to see costs above the inputs.
- Review the summary cards, table, and chart.
- Download CSV or PDF for reporting or team planning.
Example data table
This example shows how overlapping communication and writing can expand schedule loss across a day.
| Field | Example value |
|---|---|
| Study label | Deep Work Sprint Review |
| Task A | Inbox Triage |
| Task A single-task value | 18 minutes |
| Task A dual-task value | 23 minutes |
| Task B | Report Drafting |
| Task B single-task value | 40 minutes |
| Task B dual-task value | 52 minutes |
| Weights | 0.45 and 0.55 |
| Planned session minutes | 90 |
| Context switches | 5 |
| Minutes lost per switch | 1.5 |
| Shared overhead minutes | 4 |
| Daily repetitions | 3 |
FAQs
1) What is dual task cost?
Dual task cost is the percentage change between single-task and dual-task performance. It estimates how much performance drops when attention is divided across two tasks.
2) Why can the cost be negative?
A negative result means dual-task performance was better than single-task performance. This may reflect practice effects, easier conditions, measurement noise, or a helpful pacing effect.
3) Should I use time or accuracy values?
Use whichever metric best represents success. Time works well for workflow planning, while accuracy, completion rate, or output quality may better reflect performance-critical tasks.
4) Why does the calculator ask whether higher or lower is better?
Some measures improve when numbers rise, like accuracy. Others improve when numbers fall, like completion time. The direction setting applies the correct cost formula.
5) What do the task weights do?
Weights control how strongly each task affects the overall result. Use larger weights for higher-priority tasks, more valuable outputs, or more time-consuming activities.
6) How is the lost-time estimate calculated?
The tool converts weighted cost into minutes using the planned session duration. It then adds shared overhead and context-switch penalties to estimate schedule loss.
7) What is the dual-load index?
The dual-load index combines performance cost with switching and overhead pressure. It gives a quick signal of how demanding the combined work pattern feels in practice.
8) When should I trust the result most?
The estimate is strongest when tasks, timing, and measurement units match real work conditions. Repeated observations usually produce more reliable planning decisions than one trial.