About

Accurate time estimation is the bedrock of professional reliability. The Planning Fallacy - a cognitive bias where tasks take longer than expected - often leads to missed deadlines and crunched workflows. This tool is not a simple date subtractor; it is a Workflow Simulator.

By accounting for W (Working Hours), B (Breaks), and Weekends, this calculator maps raw effort hours onto a realistic calendar. Whether you are a student calculating the latest possible moment to start a thesis, or a project manager determining a ship date based on team capacity, this engine provides the TRUE temporal constraints.

Formulas

The core logic converts Raw Effort into Calendar Span. The fundamental relationship for the Latest Start Time (T_start) is:

{

T_start = T_deadline − D_task × (1 + b)H_daily − H_breakadjusted for non-working intervals ∩ W

Where D_task is the estimated duration, b is the safety buffer percentage (e.g., 0.20), and W represents the set of valid working blocks defined by the user schedule.

Reference Data

Metric / Coefficient	Value	Description
C_optimism	1.2 - 1.5	Typical multiplier applied to estimates to counter the Planning Fallacy.
Standard Workday	8 hrs	The global standard for full-time effort calculation (ISO 8601 reference).
Productive Efficiency	0.75	Real-world ratio of focused work vs. total desk time (approx. 6 hrs/day).
Context Switching	−20%	Productivity loss per additional concurrent project.
Crunch Mode	> 50 hrs/wk	Threshold where error rates increase exponentially (E ∝ h²).
Pomodoro Cycle	25 min	Standard focused interval for high-intensity cognitive tasks.

Frequently Asked Questions

This usually happens because the tool strictly respects non-working hours. If a task requires 10 hours but you only work 4 hours a day, the tool spans the task over 3 calendar days. It also skips weekends and sleep hours, pushing the start date back significantly to ensure the deadline is met within working constraints.

The buffer adds a safety margin to your raw duration estimate. For example, a 10% buffer on a 10-hour task treats it as an 11-hour task. This accounts for unforeseen delays, research time, or revisions, providing a more realistic "safe" start date.

Yes. If a task's duration crosses your defined lunch hour, the calculator pauses the "work timer" during that break. The task will finish later (or must start earlier) by exactly the duration of the break.

Yes. Enable "24-Hour Operation" in the settings. This effectively treats every hour of the selected days as a working hour, useful for server migrations, rendering tasks, or shift-based industrial planning.