What is Free Float (Free Slack) and how to calculate it in a network diagram
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Project Management Tutorial: What is Free Float (Free Slack) and how to calculate it in a network diagram.
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Other material I was using made no sense to me. In less than 3 minutes of your video it all makes sense now. Thank you. Very helpful.
You're an absolute hero. I went through a number of your PDM videos and they made my homework so much easier and enjoyable to learn
you have the best way of explaining these things that make it sooooo easy to understand. thank you.
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I have a PM midterm today and your videos really helped me a lot! I basically studied from them. Clear, step by step and well explained. Thank you !!
same pro i have tommorow
This is very simple and extremely useful and catch able.
You made this so easy. Passed the exam today and your video’s helped me make a breakthrough. Thank you
Amazing!! Thanks for letting me know 🥰
Excellent ...simple to understand. Thanks
Can you give me your resume to send to Lambton College in Canada? you are so much better than my teacher. thank you a lot, your explanation save me millions of times.
Hahaha I wish! I can give you engineer4free.com/project-management though to share with the other students in your class 😏
Thank You very Much... I have my finals tomorrow and your videos helped me a lot..
Ashish Mansur Husain haha i'm having exam next week.. the video explains more clearly than my prof did 😅
lol you are studying a day before your finals...you need to be serious. how did u do anyway
being a professor really doesn't make you a good teacher
Simplified session. Thanks!
Great explanation. Thanks.
This is very helpful lecture, nice one
and super good explanation. Thanks!!
Thanks for letting me know! :)
Just perfect , Well Done
Thanks very much for these vids. Finding them extremely useful.
Glad to hear it. Thanks for commenting :)
This cleared up so much for me. Thank you
+J. Mc. Glad to help, thanks for the feedback! You can check out all the other PM tutorials that I made here: www.engineer4free.com/project-management
Thanks, Sir! Simple, clean, easy.
You're welcome! The full playlist is here too: engineer4free.com/project-management =)
Awesome! Thank you!
You cleared my doubt you are best teacher thanks
thank you such an wonderful teacher
Thanks for watching!
Awesome vids, thanks! I needed that!
Thanks for the comment!! Glad they help :)
thank you so much sir...you saved my semester
That's awesome to hear. Glad I could help =)
Woww!! You are such an amazing life savier! I passed my exams thanks to you!
That's awesome!! Thanks for letting me know :)
FF is useful as it tells you how many days for example you can delay an activity before the TF (not the project end date) can be affected.
thanku somuch helped a lott!
thanx very much, ur videos really helped me pass my exams
this is very educative. please continue.
Thanks! I made 46 free PM tutorials, you can find them all here: engineer4free.com/project-management
Final Exam.. T-minus 4 hours. THANK YOU.
Hope the exam went well!!
@@Engineer4Free same here!
Same here
@@sa34w Best luck!!
i feel this on a spiritual level
So helpful! Amazing and simple explaination... Thank you alot! Helps me in my masters degree for engineering in project mgmt. ^-^
Glad it was helpful! Link to full PM playlist is in the description 😁
Free float is measured by subtracting the early finish (EF) of the activity from the early start (ES) of the successor activity.
simply, FF = ES.successor - EF.activity
in your example:
FF = 15 (ES last activity) - 13 (EF predecessor activity) = 2
but you are still doing excellent work for all of us... keep it ...
Then for the last activity will it be always equal to Total float of the activity as it doesn't contain any successor?
You rock my friend
best videos ever! thank you so much sir! KEEP GOING :)
Thanks Archana!! =)
very much useful tq very much
Thank u very much
Thanks dude. this is really helpful.
Glad it helped! You should check out the full playlist here: th-cam.com/play/PLOAuB8dR35oeyKU0ojIxD8Muf6Mwc8ugW.html =)
Good initiative
Nice video
thank you for your help great vedio clear quality helpful for exam
Glad to hear it, thanks for the comment!
you've made this clear, my only suggestion would be to continue with the first example, so the user can follow the entire problem from beginning to finish. we can then check our answer. otherwise, this was great! I was able to follow.
Ah that would have been very sensible. Thanks for the feedback!
thanks, that was very helpful.....
Glad I can help Moussa!!
Well done on this post you clarified my misunderstanding!!
+gmbrowne1 Thanks for the feedback, its always great to know that the videos are helping! :)
thanks teacher u really helped me alot i hope u can see my comment and smile
Thanks legend
Thank u so much !!!
You're welcome! Full playlist is here: engineer4free.com/project-management =)
Legend as always!
Thanks Gideon!! =)
شرح رائع. شكرا لك.
=)
Awesome and easy explanation. Thanks a ton. :)
Thanks yo
@@Engineer4Free You're welcome. Btw I cleared PMP last week in my first attempt. 🙂🙂
@@RiteshAgarwalGwalior amazing!! Good job 👏👏
I have tried to find your video on how to calculate "Independent Float but I have not been successful, please send a link to the video where you've calculated 'Independent floats".
Can you have a negative free float?
Awesome
Thanks 🙏🏻
Bless up
Thank you so much! Your videos have helped. Quick question, is there a calculation error. Shouldn't the ES for D and E be 10 and not 9? I thought we're taking the larger number. Thanks!
Oops, never mind! Two different successors. :-)
Superb video, really helpful (Y)
Thanks Dirinatt!
Many thanks *TH-cam HERO*!!!
RAY S Thanks for the feedback Ray, glad to hear its helping!
Very helpful! And can you show us hiw to do Optimistic time, Most likely time and pesmistic tume
Some people were born to teach!
Thanks Toyin!! :)
Good! What happens with a negative total slack?
can you please elaborate independent slack/float?
Omg You are ducking awesome :o
hahaha thanks dowg =)
Very well explained.. Thanx..
N My professor at IIM, could not explain this properly, in-spite of having a rich experience from KPMG. The simplicity with which you explained is awesome..
+Pradeep Chopra oh wow, we'll I'm glad the video did it's job. Thanks for the comment!
very useful
Thanks for watching!
Your explanations are wonderful - clear and concise. However, I was taught that the formula for free float was ES of successor minus LATE START of predecessor minus 1. I like your way better - I am studying for the PMP and am now worried that I no longer understand how to calculate free float as your explanation and others differ....HELP? Thanks.
Little Canvases Hey I do not specifically follow PMP terminology and methods. I teach these in accordance with a university project management course. If you are studying for PMP, you should follow their methods. I certainly do not want to mislead you, but I'll give a little insight in to what I'm doing and maybe it will help clear up at least what your seeing me do. My PDM network diagram defines 0 as the start of day one, 1 as the end of day one and the beginning of day two, 2 as the end of day two and the beginning of day three, 3 as the end of day three and the beginning of day four, and so on... (here is an Gantt chart example that shows how for example, "2" can be the end of day two and the beginning of day three: www.engineer4free.com/4/how-to-draw-a-gantt-chart). Not everyone starts at "0", some people start at "1". Please confirm the start number for PMP. I will use numerals (ie: 1,2,3) to refer to my numbering system, and spell out numbers when referring to actual days in the project (ie: one, two, three). Durations are absolute, so for example, a duration of 3 actually equals three days of the project. So lets consider activity E. It has ES = 10. This means its starting at the beginning of day eleven. Its duration is 3, so this activity will be carried out during day eleven, twelve, thirteen (ending at the end of the work day on day thirteen). The ES of activity F is 15, meaning that it can start at the beginning of day sixteen. The # of free days between the end of day thirteen and beginning of day sixteen is 2 (all day fourteen and all day fifteen). So without using either of our formulas, you can see that we have 2 days of play where we could potentially delay activity E without delaying the day sixteen start of Activity F. My formula reflects this as FF = 15 - 10 - 3 = 2. I see a "-1" term in your equation, this probably reflects a different system for the numbering of the PDM network diagram. Perhaps if your project starts at "1" instead of "0" like mine, then all of the ES, EF, LS, LF will be shifted by one day compared to what I have, which would explain the "-1" term appearing in your equation. My best recommendation is draw a Gantt chart, and figure out actually which day of the project each activity is starting and finishing and reason through it visually, because the numbering system for ES, EF, LS, LF is only relative to the start # that you define (whether its 0 or 1). For an exaggeration, you could demonstrate the relativeness of the numbering system by potentially labeling the start of day one as "50" then activity A would end on the end of the fifth day and it's EF would be would be "55".... Long story short, I'm unfamiliar with your formula, but the "-1" is highly suggestive that there is a difference in the numbering system by 1. I hope this doesn't confuse you more, and as you are studying for PMP, you should use their methods. Good luck!
FF=smallest Es of all succ Act. - Ef of the act. ( EASIER )
Gr8 example
Thanks abhay!
i like your video whats program you used ??
Hey Zaid, thanks. It's basically just hand drawn, it's not PM software. You can check out all the hardware and software that I used to make it at engineer4free.com/tools
Is it useful? mmmmm.... questionable... will it be asked from you from your teacher? Probably.
Story of my entire degree
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hi do u have some video of Float Straight line distribution? and with risk? thank u
Hey Hj, I'm pretty sure I don't. Doesn't sound familiar or like an alternative name to something else I've done. You can find all my PM videos here: engineer4free.com/project-management give a browse through them =)
final exam tomrw .Thank you so so so so much
Good luck! Make sure you check out engineer4free.com/project-management for all the rest of the videos!
I love you❤❤❤
Thank you so much for your helpful video
Could you help to Identify any non-critical tasks ?
Basically anyone that the ES and LS are not equal
is it possible to write this short equation?
Free Float = Minimum ES.suc. - EF.act.
So if activity B or C is 4 the FF of activity A will be 5-4=1 ?
FINAL EXAM T-MINUS 15 MIN!!! THXXXXXXX MANNN
hahaha how did it go!?
Engineer4Free nailed it!!!😍😍
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Then for the last activity will it be always equal to Total float of the activity as it doesn't contain any successor?
Watch out for situations where there are multiple final activities, like the example in this video: th-cam.com/video/R31K0CMoOho/w-d-xo.htmlsi=5bh_EhDJEYPrBDkr I explain what to do there
What about easy formula : FF=successor ES - predecessor EF does it work?
Is it possible to have a negative free float?
not that I'm aware of. I'd ask your instructor. It may simply indicate that you have a math error.
it looks like the free float is difference between Earliest start of successor - earliest finish of the current activity.
Yeah pretty much. Sometimes you can have more complicated relationships between activities and the longer expression accounts for that.
wht is independnt flot
I find that starting on day 1 as Day 0 is confusing. PMBOK v5 uses the standard as 1 for Day1. It also makes sense because if EF of activity A is day 5, then ES of activity B is day 6. Right now, both are Day 5 which is strange because activity B is a successor to activity A and there is no lead. So how can they end and start on the same day?.
Formula for Free Float = (Min of ES of successor - Early Finish of Predecessor) - 1
i.e [Early start of (B or C) minus Early Finish of predecessor A] minus 1
(ES of B - EF of A) - 1
+Michael Douglas Make sure to watch videos only with day 1 as 1 and 0. That is crap. please go and watch Aileen Ellis' videos. She explains so many things so well and she also has her own company training people as well as writing books on how to solve every EMV and contract problem for PMP.
+Cecil D'Souza I teach project management concepts the way that I learned in university. If you find my numbering confusing, then feel free to utilize other resources to learn. While my method may not match exactly with the PMBOK Guide, it does follow a logical flow. It's based on how I write Gantt charts (link: www.engineer4free.com/4/how-to-draw-a-gantt-chart). I start my Gantt charts at time "0", as charts should, and the same as my PDM network diagrams. If you watch the Gantt chart video, you see that Activity A is two days long, starts at "0" and ends at "2." "0" represents the start of day one. "1" represents the end of day one and also the start of day two. "2" represents the end of day two and the beginning of day three, and so on. Assuming we have regular 8am-5pm work days, it first seems strange that "2" could represent both 5pm on day two and 8am on day three, but the shape of the Gantt chart should look familiar to you. By doing it this way, I don't need to subtract an extra "1" when calculating free floats. I personally prefer it that way and hence teach it that way. If you find it confusing and don't want to learn this way then by all means, there are many other teachers on TH-cam and the rest of the internet that you should be able to find some lessons that start their numbering at 1. Good luck in your studies!
In Activity C, FF = 2 not 0 (Correct me if I'm wrong)
3CE-C
Isn't Free Float simply = ES of successor minus EF of predecessor? why need to go thru more steps to minus duration and minus ES of predecessor?
Yeah that works for simple finish-to-start relationships. It all starts to crumble though for finish-finish, start-start, and start-finish relationships. It's always a good idea with those to sit back and think if what you calculated is reasonable and makes sense, not just following the given formula :)
Oh. thks.. so its no that straight fwd..lol. means your formula of Min ES (Successor) - ES(Activity) - Duration (Activity) will cover all scenarios?
sorry You have some mistakes - in calculating the Early start of the activities - Eg; if you finished on Monday 5, the next activity must start on 6 - not the same day - but your concept is great
hey Maher. There is no mistake, the numbering system that I use comes from how I draw Gantt Charts. Please watch this video: www.engineer4free.com/4/how-to-draw-a-gantt-chart You can see on the Gantt chart, that 0 represents the beginning of the first day. 1 represents the end of the first day AND beginning of the second day. 2 represents the end of the second day AND the beginning of the third day. And so on. 5 would represent the end of the fifth day AND the beginning of the sixth day. The numbers of the Gant chart come through on the network diagram as the early start and early finish values. They are just labels, and need to be properly interpreted as to the actual points in time that they refer to. Hope that helps clear it up!
i have final exam after 2 days......
Good luck! Hope you ace it =)
@@Engineer4Free thanks dear....
Of all the youtube vides i find your more easy for calculation the Critical float and total float. But one suggestion for free float , why do we need to do
FF = Minimum of (ES-successor )-ES-Activity-Duration activity ?i.e X-Y-Z
Why cant we choose
FF = Minimum of (ES-Successor) -EF-Predecessor o ? i.e Simple X-Y instead of X-Y-Z
Example :
In this diagram Free float of E will be Minimum of (F Node ES-Successor) - E Node of Predecessor EF
ie. 15-13 = 2
This will be much more easy (X-Y instead of X-Y-z) . Any logic to use subtraction of three variables ?
+Rama Krishna If you are just dealing with "finish to start" relationships, then you're simplification is valid. When you advance to "finish to finish," "start to start," and "start to finish" relationship everything gets a lot more complicated, and the simplification may not work every time.
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this system only works if someone considers the day zero as the start day. There is no day zero in real life.
Hey, there is no zeroth day of this project. There is a first day, second day, and so on for a total of 19 days. Some people follow a method of starting network diagrams with a 1, and some people start it at 0. If you prefer starting at 1, then do that, but just be aware of what the "numbers" actually represent in real life. If you are curious why the method I use starts at 0, it comes from the way that I draw Gantt charts, you can see a simple example here in this video: th-cam.com/video/NcOmJSrXYoQ/w-d-xo.html each "column" represents a day, so 0 on the horizontal axis marks the start of the first day. 1 marks the end of the first day and also the beginning of the second day. 2 marks both the end of the second day and the beginning of the third day, and so on. So in that video you see that Activity A is 2 days long, and it's bar on the Gantt chart starts at 0 and ends at 2, spanning two "blocks" or "columns." The logic continues up until the end of the project, in that video, the project is 12 days long, so its network diagram would start with a 0 and end with a 12 if you follow the convention that I use. That is why in this video that we're commenting on, the project duration is nineteen days, so we end up getting a 19 in the network diagram at the end, which represents the end of day nineteen. Take a look at this post too, I have a Gantt chart and a network diagram beside each other, so you can observe how the numbering works: www.engineer4free.com/extras/gantt-chart cheers man, hope that clears up the confusion. If you or your professor prefer to use a convention that starts at 1, then just go with that and notice that our "numbers" would be off by one the whole way, but the activities would all actually start and stop at the same times no matter how you define the numbering system.
francisco martinez ...works by starting on day 1 as well...what you don't understand is that day 0 means the day has not passed yet which is why a 1 day activity starts AT day 0 and finishes AT day 1.
Yup thanks for the much more concise explanation, thats a great way to put it!
This explanation does not go inline with PMBOK standard.
You're an absolute hero. I went through a number of your PDM videos and they made my homework so much easier and enjoyable to learn
Glad I could help!!! =)
Just perfect , Well Done
+Mamdouh Mandouh Thanks for the feedback! You can find the rest of the project management turorials I made here: www.engineer4free.com/project-management :)