(Lightning) Critical Strike Chance

Hey fellow runemasters,

I need your help with Critical Strike Chance. At the moment, I have 81% Spell Critical Strike Chance according to my character sheet. In addition to that, I have 70 % increased Lightning Critical Strike Chance with two idols (1 x 30% and 1 x 40%). But I don’t know how much Crit I actually have.

How do I calculate the increased Lightning Critical Strike Chance into my Crit Chance of my character sheet? Can someone help me with this?

Thanks in advance.


The 81% you see in the character screen is already a result of a calculation, so it isn’t helpful.

Instead, you need to go through all your gear, passives and skill passives, and find everything that affects your crit, and apply that into the formula. The formula (simplified) is like this:

(base crit chance + flat crit chance) * (1 + increased crit chance total)

In your case, we’re talking about Lightning Spells, therefore

(base Spell crit chance + flat Spell crit chance) * (1 + increased crit chance total + increased lightning crit chance total)

  1. Each spell starts at 5% base crit chance.
  2. AFAIK “Crit Chance” applies to spells, but “spell crit chance” doesn’t apply to melee.
  3. Examples of flat “+% Critical Strike Chance”. Skills have it, for example Frost Claw has “Rending Cascade”, that’s +2% flat crit chance.
    Another example, unique item Prismatic Gaze has “+(2% to 4%) Critical Strike Chance”. Flat bonus is easy to spot - the word “increased” is missing. Adding that helmet bonus to the base:

5 (base) + 4 (helmet) = 9% Critical Chance

  1. Example of adding together “+% Increased Critical Strike Chance”. Your “+30%/+40% increased lightning critical chance” idols and the “+40% increased critical chance” from that unique helmet from my last example.
    Easy to spot increases too - they always have the “increased” word.

30 + 40 + 40 = 110% increased Spell Critical Strike Chance

  1. All together

(5 + 4) * (1 + 1.1) = 18.9%

wow, thank you very much for this very detailed answer.

According to my runemaster: Runemaster, level 100 (Release / 1.0.4) - Last Epoch Build Planner and your explanation I get the following (Spell) Crit Chance:

(5 (Base) + 4 (Prismatic Gaze) * (1 + 785,2% + 70%)
(5 + 4) * (1 + 8,55)
9 * 9,55

So my real Spell-Crit-Chance Value is 86% (if I calculated correctly ^^) instead of the 76% shown at lastepochtools or the 81% shown in my character sheet ingame. Why is that? Why is it so hard for EHG, or for lastepochtools, to calculate this correctly with all variables? This is not a rant, I’m just curious.

@Psojed thanks again for effort and this very valuable answer. You helped me alot.

Yeah. Unfortunately, Last Epoch Tools sucks :rofl:

  • Tools doesn’t use the same values as the items ingame.
    For example, your Primastic Gaze gives +4% flat crit, but tools only counts it as +3.58% flat crit. If you are on the “Actual” tab.
  • Similarly, every “increased” affix on your items is the same. Your ring implicits are 50% (left) and 49% (right), but tools counts them as 49.61% and 48.82% respectively.

You can hover the Spell Crit number in the Offense section to see a list of bonuses that are counted. But even these lists of values can have errors.
For example Mental Catalysis…

Runemaster passive, +6 INT if you have a Catalyst

…is accounted for in the Intelligence calculation, but it isn’t accounted for in the Increased Spell Crit calculation, so tools says Calculated Destruction only gives you +225%, while it should say +243%.

  • Finally, tools only shows Spell Crit, not Lightning Spell Crit. This is easy to spot - your idols won’t be in the list of counted bonuses I just mentioned.

Why is it so hard for EHG

Well, EHG is calculating it correctly (at least I hope so :smiley: ).
It’s just that your character screen is also showing you the generic Spell Crit Chance, not Lightning Spell Crit Chance, so the idols are also not counted there.

I got curious so I did the math. I used the list from LE tools and fixed the wrong values:

40 + 17 + 32 + 50 + 95 + 49 + 73 + 26 + 82 + 35 + 60 + 243 = 802

So, your total Increased Spell Crit Chance should be 802%.
Your total Increased Lightning Spell Crit Chance should be 872%.
With 5 base and 4 flat:

Spell Crit Chance:
(5 + 4) * (1 + 8.02) = 81.18, rounded down to 81%.

Lightning Spell Crit Chance:
(5 + 4) * (1 + 8.72) = 87.48, rounded down to 87%.

Great thread, thanks.
I’m fairly new to the game, still only level 25, but am trying my own builds as, inefficient as it is, I enjoy that part of the game almost as much as playing.
I wondered, if I was wanting to play a Staff wielding spellblade, whether to invest in crit chance as I’m leaving dps on the floor by not using a dagger, for example.
I like investing in crit as a general rule, is it inefficient for endgame to invest in crit if I’m going to stick to staffs or non ‘base crit chance’ weapons like dagger? Or am I going to be ok through other mods and passives?

It depends on the skill and other pieces of gear you are using.

Investing into crit usually is always worth it for hit based builds. Even if you don’t get close to 100% crit, crit is still a effective more dps multiplier.

What you should try if you are not using Daggers though, is to get any form of flat base crit chance, either from the skill spec tree (if the skill you are using has that) or some flat base crit from a Unique in some other non-weapon slot. (There are a few, but not all of them are compatible with all kinds of skills, so it again depends on the skill you are using).


In addition to that, there are several itembases with crit implicit, like Amus, Rings and Gloves. With them you get a ton of crit.