Project Timeline Calculator

Estimate how long a project will take start to finish. Enter each phase in working days, add a buffer, and pick your schedule.

plan, prep, work, finish, buffer
Project Duration
days
Calendar time start to finish.

Usage Tip

Order long-lead materials and book inspections as early as you can — waiting on parts and approvals delays more projects than the actual work. Build in a buffer and expect to use it.

THE MATH
Work days = sum of all phase durations
With buffer = work days × (1 + buffer%)
Weekdays-only calendar time = work days ÷ 5 × 7
Add up the working days for each phase, then pad with a buffer for the delays every project hits. Working only weekdays stretches the calendar time by about 40% versus the raw work days.
This assumes phases run one after another; overlapping them shortens the calendar.
Permits and inspections are the big wildcards — they wait on other people and can stall everything behind them, so pad generously.
Material lead times and delivery dates often drive the schedule more than the labor does; order long-lead items early.
Weather, deliveries, and waiting for a phase to cure or pass inspection all add calendar time the work-day count misses.
Scroll to Top

The calculators and tools on Formula Factory are provided for general guidance and informational purposes only. Results are estimates based on standard formulas and the values you enter — they do not constitute professional engineering, electrical, or architectural advice. Always verify calculations with a qualified professional before making decisions for any safety-critical, code-compliance, or commercial application. Formula Factory makes no representations or warranties as to the accuracy or completeness of any result, and accepts no liability for errors, omissions, or any outcomes arising from reliance on this information.