IBU's in extract brewing

[ntculenuf]

First off I would like to thank all the people who post experienced to beginners. I use this site a lot for my questions and advice. I have not posted a whole lot (in fact this my first) as I can usually find an answer while looking around.

Currently I am getting ready to brew my 13th batch. I am slowly starting to understand more, with that seems to be more questions and a little confusion. So with all that said here is where I am today and why I am posting.
I am seeing a lot of difference in my IBU's using different recipe calculators (I understand the difference in IBU scales seeing tinseth seems to be the one used most). I have been using this one from Tasty Brew to see about where I will end up. The last few days I was looking around for a few different ones seeing different formats and such. I ran across this on from Brewgr that was mentioned on a post some where in here. so far I like the layout. What I have noticed is the brewgr one shows my IBU's way lower than the tasty recipe. so I tried different IBU calculators to compare and those are a little different answers as well but closer to the brewgr.

Thanks for bearing with me so far.
How much does your initial boil volume effect your IBU? I usually have been doing initial 3 gallon boils and topping off to 5 gallon, should I up my initial?(wort chiller is not feasible right now but soon, hopefully). I have found this helps with cooling my wort faster to pitching temp.
So far I have been happy with the results of my beer but now I am questioning my calculations with tasty brews calculator.
I guess another question would be; Is there a recipe calculator that you guys are using that is more accurate?

Again thanks for reading and thanks for the help. I hope that this came out clear. I'm off to brew

 

[grem135]

Lots of brewers in here use software like beersmith2. There is a trial version so you can test it out before buying.
It can help you with all your brewing calcs and recipies

 

[boydster]

How much does your initial boil volume effect your IBU? ...should I up my initial?
The boil volume has a big impact on IBU's because a given amount of water can only dissolve so much isomerized alpha acids before reaching saturation - at that point, you'll stop gaining IBU's regardless of additional hop additions and/or boiling time. A lot of folks will tell you that a full boil is one of the best things you can do to improve your beer. Definitely boil at least 3.5 gallons. That gives you plenty of water to work with.

Is there a recipe calculator that you guys are using that is more accurate?
I use Brewtarget, lots use BeerSmith, and there is Brew Toad online. The absolute best thing you can do is find the software you like and stick with it. If you make a recipe that your software says is "X" IBU's, take note of what that level of bittering tastes like and you'll be better able to gauge future IBU loads to target with your recipes & software based on experience. The calculations are only estimates, and your actual IBU will be lower than your calculated IBU every time due to boil-off and normal inefficiencies. Keep in mind, you aren't brewing for everyone, you are brewing for only one... yourself. Get to know the tools you like working with the best, learn you palate, and make the beer you want to make.