Increased Attack Speed
EIAS refers to how much to adjust the rate that an animation is played. Higher values of EIAS make an animation play faster.
Formulas
ΔEIAS = floor((120 * IAS) / (120 + IAS))
IAS = ceiling(120 * ΔEIAS / (120 - ΔEIAS))
Calculating necessary IAS from a target ΔEIAS
Necessary ΔEIAS = Target ΔEIAS - Skill ΔEIAS + WSM
From your target ΔEIAS, subtract any quantities of ΔEIAS from skills. This can come in the form of Skills that increase your attack speed such as Burst of Speed and Fanaticism and curses that slow your attack speed like Decrepify. Attack speed increasers have a positive ΔEIAS while speed decreasers have a negative ΔEIAS.
From that amount, add your weapon speed modifier (WSM).
-If you are single wielding, your weapon speed modifier is your weapon's WSM.
-If you are dual wielding and the weapon in your left inventory slot is your main weapon, your weapon speed modifier is (LeftWSM + RightWSM) / 2.
-If you are dual wielding and the weapon in your right inventory slot is your main weapon, your weapon speed modifier is (LeftWSM + RightWSM) / 2 - LeftWSM + RightWSM.
The resulting value is your Necessary ΔEIAS. This is the amount of speed increase you need to make up with the IAS from your equipment. If its value is negative, you don't need any additional IAS from your equipment. If it is positive, look up this value in the table below to get the amount of IAS you'll need to have in order to reach the Target ΔEIAS.
EIAS Conversion Table
| ΔEIAS | IAS | ΔEIAS | IAS | ΔEIAS | IAS | ΔEIAS | IAS |
|---|---|---|---|---|---|---|---|
| 1 | 2 | 31 | 42 | 61 | 125 | 91 | 377 |
| 2 | 3 | 32 | 44 | 62 | 129 | 92 | 395 |
| 3 | 4 | 33 | 46 | 63 | 133 | 93 | 414 |
| 4 | 5 | 34 | 48 | 64 | 138 | 94 | 434 |
| 5 | 6 | 35 | 50 | 65 | 142 | 95 | 456 |
| 6 | 7 | 36 | 52 | 66 | 147 | 96 | 480 |
| 7 | 8 | 37 | 54 | 67 | 152 | 97 | 507 |
| 8 | 9 | 38 | 56 | 68 | 157 | 98 | 535 |
| 9 | 10 | 39 | 58 | 69 | 163 | 99 | 566 |
| 10 | 11 | 40 | 60 | 70 | 168 | 100 | 600 |
| 11 | 13 | 41 | 63 | 71 | 174 | 101 | 638 |
| 12 | 14 | 42 | 65 | 72 | 180 | 102 | 680 |
| 13 | 15 | 43 | 68 | 73 | 187 | 103 | 728 |
| 14 | 16 | 44 | 70 | 74 | 194 | 104 | 780 |
| 15 | 18 | 45 | 72 | 75 | 200 | 105 | 840 |
| 16 | 19 | 46 | 75 | 76 | 208 | 106 | 909 |
| 17 | 20 | 47 | 78 | 77 | 215 | 107 | 988 |
| 18 | 22 | 48 | 80 | 78 | 223 | 108 | 1080 |
| 19 | 23 | 49 | 83 | 79 | 232 | 109 | 1190 |
| 20 | 24 | 50 | 86 | 80 | 240 | 110 | 1320 |
| 21 | 26 | 51 | 89 | 81 | 250 | 111 | 1480 |
| 22 | 27 | 52 | 92 | 82 | 259 | 112 | 1680 |
| 23 | 29 | 53 | 95 | 83 | 270 | 113 | 1938 |
| 24 | 30 | 54 | 99 | 84 | 280 | 114 | 2280 |
| 25 | 32 | 55 | 102 | 85 | 292 | 115 | 2760 |
| 26 | 34 | 56 | 105 | 86 | 304 | 116 | 3480 |
| 27 | 35 | 57 | 109 | 87 | 317 | 117 | 4680 |
| 28 | 37 | 58 | 113 | 88 | 330 | 118 | 7080 |
| 29 | 39 | 59 | 117 | 89 | 345 | 119 | 14280 |
| 30 | 40 | 60 | 120 | 90 | 360 | 120 | infinity |