Job Duration Calculator Formula

Understand the math behind the job duration calculator. Each variable explained with a worked example.

Use the Job Duration Calculator

Formulas Used

Working Days Needed

days_needed = (workers * hours_per_day) > 0 ? ceil(total_work_hours / (workers * hours_per_day)) : 0

Weeks Needed (5-day weeks)

weeks_needed = (workers * hours_per_day) > 0 ? ceil(total_work_hours / (workers * hours_per_day)) / 5 : 0

Hours Per Worker

hours_per_worker = workers > 0 ? total_work_hours / workers : 0

Variables

VariableDescriptionDefault
total_work_hoursTotal Work Hours Needed(hours)200
workersNumber of Workers4
hours_per_dayHours Per Day(hours)8

How It Works

How to Calculate Job Duration

Formula

Days Needed = Total Work Hours / (Number of Workers x Hours Per Day)

This gives you the minimum calendar days required. In practice, add buffer time for weather delays, material availability, inspections, and other interruptions.

Worked Example

A project requires 200 work-hours with 4 workers working 8 hours per day.

total_work_hours = 200workers = 4hours_per_day = 8
  1. 01Daily crew output = 4 workers x 8 hours = 32 hours/day
  2. 02Days needed = 200 / 32 = 6.25, rounded up to 7 days
  3. 03Weeks needed = 7 / 5 = 1.4 weeks
  4. 04Hours per worker = 200 / 4 = 50 hours

Ready to run the numbers?

Open Job Duration Calculator