Each developer has 5 dev days a week. We have 4 back end developers.
We have 20 dev days in a week, or 80 in a a month total.
1. Add up estimated dev days from stories
2. Since we spend 1 days worth of work a week doing other things, add 20%
3. Devs take an average of 6.5 weeks off a year, including vacation, being sick, and stat holidays, so add 13%
4. Add 10% for mid project changes
5. Divide by total developers working on the project
6. You have your total time in working days!
Total Dev Days Estimate * 1.20 * 1.13 * 1.10 / Total Devs On Project = Total Working Days Till Deadline
From working days till deadline you can get the total weeks till project completion by taking the start date,
and adding (Total Working Days Till Deadline / 5) weeks.
(50 * 1.20 * 1.13 * 1.10 / 4) = 19 total working days duration
Start date = January 1st
Deadline = start date + (18 / 5 = 3.7) weeks
Deadline = January 26th