So you're like me, you're sitting on the AH looking at a bow wondering.... hrm is this going to increase my dps by enough to make it worth my while? or is it going to be a million gold of worthlessness? Well wonder no more, a guy by the name of Dretar over on the eu side of things has made a spreadsheet that does teh hard part for you. Simply put you plug in your stats on every piece of your gear in the two sections. When you see a new item you plug it's stats in to one of the sections and then you look at the dps difference and stat differences. It's really quite elegant and once you set it up, you only need modify it as you get new gear!

Below is his post on the forums and a link

http://eu.battle.net/d3/en/forum/topic/4551698386

"Hello there,

Wanted to share with you guys a tool I've created in order to simplify high-end gear comparison and making it easier to make fully aware purchase decisions on the AH by knowing the impact on your DPS before making the actual purchase.

Basically it is an Excel spreadsheet with 3 functions.

1) Gear comparison.

2) Specific stat change influence on your build damage.

3) Absorption calculation.

Number 1 is achieved by data input in the green marked areas on the left side for both variants, which should give you the picture of the final stat of the builds and damage difference.

Number 2 can be done via the little table below by typing in changes such as (-100 Dex, + 15% IAS, + 30% crit dmg).. The result is the Final DPS change (without sharpshooter maxed).

Number 3 is done be proper entry of gear data to the 3-rd sheet, which allows to see your current mitigation versus various damage types and sources.

Information about the spreadsheet - Read before using:

1) I assume you use a ranged weapon.. Naturally a DH can run around with a spear but well.. 

2) Sheet is protected so You don't accidentally mess it up. The only cells that You should write up data in order for the sheet to work are marked with a green color.

3) IAS = Increased Attack Speed, for those that are not familiar.

4) The sheet is filled in with some entry data so You can see how it is supposed to look like.

5) Note that the little table below is a simplified model that should rather be used for 1-variable change testing, it will only give approximated data when used for multiple variable changes. It also serves to calculate weights of specific stats, which show the impact of "change of 1" of specific stat to Your DPS. Mind that this table is dependant on the gear figures of Variant 1 only.

6) It is Vital to select from the scroll-down list the appropriate Weapon Type for both Variants (cells B3 and B19) since the base weapon speed and the archery passive bonus are derived from the weapon type.

7) The file consists of 3 sheets. The first sheet is devoted to single-wielding style, the second to dual-wielding style, the 3rd for the purpose of absorption calculation.

8) The spreadsheet might not be 100% precise in cases of weapons with +XX% damage affix, because of the rounding error, since the spreadsheet assumes whole numbers, which might not be the case.

9) The dodge calculation is an estimate, so it might not be 100% accurate. (But works fine for tested sets of equipment).

FAQ:

Q1) Is there a way to disable sharpshooter, because it inflates the value of Crit DMG and underestimates Crit chance?

A1) There are 2 figures representing Your final DPS: 1) "Final DPS", 2) "Final DPS with sharpshooter maxed". If you are interested in your base dps without the use of sharpshooter passive or without any bonus crit chance from it, refer to the figure in 1). Since version 1.2 You can also disable sharpshooter by selecting "NO" to sharpshooter in the passive in the section.

Q2) How should i input data from gear with for example +13-26 damage from an amulet?

A2) By typing in both 13 in "MIN DMG" and 26 in "MAX DMG" in the row devoted to the amulet slot of one of the variants.

Q3) I have input all the data as required but i keep getting "###" instead of the dps, what's wrong?

A3) "###" in Excel means that the column is too narrow to present the figure. Widen it and It'll be fine.

Q4) Where should i input the +X% damage from my weapon?

A4) You should not enter this anywhere, because it is already taken into account in the weapon minimum and maximum damage that you should enter to the spreadsheet.

Q5) Your spreadsheet says that the crossbow has a base attack speed of 1.1, but my one has 1.23, what should i do?

A5) Your weapon has an attack speed of 1.23 beacuse it has IAS on it. The base weapon speed is still 1.1, but due to the bonus it is enhanced to 1.23. Therefore you should enter the IAS bonus from your weapon to the row of weapon statistics in the AIS column.

Q6) What does "Assume Dodge as damage reduction" mean?

A6) Dodge itself does not reduce the damage taken but gives a chance to completly avoid the damage, but in order to reflect its importance in damage reduction this option has been added. It gives you a chance to simulate how much damage would you take in case of being attacked by an infinitely large amount of attacks dealing infinitely small damage, in which case dodge acts simply as damage reduction instead of chance to avoid damage.

Q7) The spreadsheet does not consider crit chance when i input it with a dot (like 3.5%) What's wrong? - (Rare occurrence)

A7) Try using a comma (like 3,5%). It might occur when using a different software that does not automatically adapt into various regional settings. The spreadsheet has been written using Polish settings in MS Excel where it is accustomed to use (,) as a decimal separator.

If you have any questions concerning the calculations/spreadsheet feel free to write them down.

And don't forget to thumbs up! :)

Current version of the spreadsheet: 1.3"

you'll have to go to his rapidshare link for the latest one, and it DOES work in OpenOffice 

https://rapidshare.com/files/2417408472/DH_Damage_Calculation_v1.3.xlsx