2 packets of dry-yeast, or more?

Hi, I'm planning on making the beer below in ~2 or so weeks, and ordered 2x Safale US-05 Ale Yeast packets. Should that be enough for a beer with an OG of 1087?

As an option, I have an IPA in primary right now that will be ready to rack to secondary about the same time 115th Dream kit arrives - so is it worth also adding some of the yeast cake from that (also US-05)?

115th Dream Hopbursted IPA Extract Kit
http://www.northernbrewer.com/shop/115th-dream-hopbursted-ipa-extract-kit.html

Thanks

2 packets will be plenty. I brewed an IPA with a 1.076 OG and used one pack of US-05 without a problem (tastes great!). From what I've read US-05 is good for up to 10% ABV, so depending on how dry your IPA finishes could be borderline with one pack. Pitching two packs would definitely have you on the safe side.

You can always use Mr. Malty's Yeast Pitching Rate Calculator. According to it, you would need about 1.5 packs of dry yeast in order to get to the correct pitching rate.

You can find it here: http://www.mrmalty.com/calc/calc.html

Try out Mr Malty. It looks like from that you will need 1.5 packets so 2 will definitely be enough.

edit: dbhokie beat me to it

Have you thought about a stir plate and flask? You can grow whatever size starter you need in just a couple of steps. You can then freeze the rest and grow it again later. As the prices on yeast continue to rise, I have started to gather the gear for yeast farming in earnest. At the rate prices are climbing your'e gonna have to do something to cut the costs soon anyway. Grow youre own yeast and hops and save around 10-15 bucks a batch, buy bulk grain and save another 5 to 10 too. I am hoping to get my actual per batch cost into the 13-15 dollar range possibly even less if I can find free shipping on grains that are in stock and fresh. Just sayin.......
Bob

2 packs will be plenty

Excellent advice, and thanks for the link. Glad I asked...