Skip to main content
Skip to main content

📅 Project Duration Calculator

Estimate project duration based on work scope, crew size, and productivity rates.

Quick Formula​

Basic Duration​

Duration = Total Work ÷ (Crew Size × Hours per Day × Productivity Rate × Working Days per Week)

With Buffer​

Duration with Buffer = Base Duration × (1 + Contingency Factor)

Common Duration Factors​

Weather Days​

ClimateWeather Days per Month
Mild1-2 days
Moderate2-3 days
Severe3-5 days

Working Days​

Working Days = Calendar Days - Weekends - Holidays - Weather Days

Common Calculations​

Example 1: Simple Project​

Work: 5,000 sq ft framing Crew: 4 workers Productivity: 75 sq ft/hr per worker Hours: 8 hours/day Working days: 5 days/week

Calculation:

  • Daily output: 4 × 8 × 75 = 2,400 sq ft/day
  • Days needed: 5,000 ÷ 2,400 = 2.08 days
  • With 20% buffer: 2.08 × 1.20 = 2.5 days (3 days)

Example 2: Complex Project​

Work: Multiple trades, 10,000 sq ft building Crews: Various (concrete, framing, MEP, finishes) Schedule: Sequential phases

Phases:

  • Site work: 2 weeks
  • Foundation: 2 weeks
  • Framing: 4 weeks
  • MEP: 3 weeks
  • Finishes: 4 weeks
  • Total: 15 weeks

Contingency Factors​

Project TypeContingency
Simple, repetitive10-15%
Standard15-20%
Complex20-30%
High-risk30-40%
Plan for Delays

Always add contingency to duration estimates. Weather, material delays, and unforeseen conditions are common.