Take a look at my Nugget IPA

I've had a quarter oz of nugget that I've been wanting to make an IPA with. Think I'm brewing this bad boy up tonight.

10# 2 row
1# C60
.5# sugar
.25# Wyerman dark crystal

I'm then going to blend Nugget and Columbus 50/50 and do the charges like this:
1oz @ 60
1oz @ 15
1oz @ 10
1oz @ 5

Pitch US05

After two weeks dryhop with 1oz Columbus and 2oz Nugget for 5-7 days.

1.060/ 75 IBU/ 11 SRM

If it were me, i'd change the 15 to 20 mins, then combine the 2 oz at the end at flameout.

That looks good to me. I personally like the 60,15,10,5 routine. Should definitely get some good hop bitterness, flavor and aroma through all those additions plus dryhops.

My last ipa was fwh, 15, flame out, dh. I liked it, but I want this one to have a firmer bitterness, along with good flavor. And hopefully some "punch you in the face" dh aroma. I'm thinking I might change that 5 addy to flame out/steep. We'll see.

To me it depends on the og and how many hop varieties you use, if its a single hop I usually go with a BU:GU .9-1:1
For example 60 ibu to 1.060 OG
If using 2-3 hop varieties I tend to get more extreme as I want the individual bitterness and flavor of each variety to come through therefore I go more 1.5:1 BU:GU, I am working on a black IPA Hopped with Columbus, Centennial and Cascade and dry hopped with Amarillo that has 130 ibu and a gravity of 1.076.

About to start the boil. Now I'm tossing around going 20,15,10,flame out. Hmmm. Whatever. I'll probably decide when I do it. That tends to be the pattern.

Scratch that. I meant 60,20,15,flame out. Sorry. I shouldn't post on my phone.

I ended up brewing the recipe as written in the OP. My propane burner blew out at sometime during the boil when I went to go make a sandwich. Since my IbUs were going to be wacky anyway, I just went with the first version. No worries though, I have a feeling that IBU listings are just general estimates most of the time anyway. Should be good either way. It'll be beer anyway!

There are calculations for ibu, it includes corrections for gravity and boil volume.

I know. I have beersmith. Just saying that I doubt the calculations (through no fault of the program) are really that accurate anyway. Plenty of problems (measurement, aging, etc) to go around. I'm a sceptic though. Unless you send a sample to a lab, you're only guessing anyway as far as I see it.

The whole thing is you have to assume some level of clarity for that matter there are a dozen other things that will throw your calculation off, however, the IBU of any given beer is a measurement of the alpha acids absorbed through the boiling process. If you can't count on them with some level of clarity they serve no purpose. I do my calculations on paper. And use pretty much a 15 minute interval hopping process, however, I use my ibu calculations to determine how much for each interval.

I think the calculations are probably closer than you think. I especially if you are buying ingredients that are fresh and well taken care of from a vendor that makes sure to properly handle hops.