Hello, everyone.

My friends and I are playing a variation of no limit holdem which only use 6-A(36 cards). And the hand rankings is the same with holdem. If I want to calculate the hand equity in this game, can I use the equity calculator for holdem and simply just set the 5-2 to dead cards?

I use the propokertools.com and simulated a hand that AdQd vs Tc9c on Qs8h7h with dead cards 5-2, and the result comes AdQd:65.01% and Tc9c:34.99%.
It's a significant difference to our manual calculation that Tc9c should have around 48% equity.(1-(1-(8/29))*(1-(8/28)))

Is there any mistake on my manual calculation? or I just can't simply set the 5-2 to dead cards to adapt the simulator to our game?

Yes.

You did something wrong. I just used PokerStove and it said T9 is about 47.4%.

Slight mistakes which mostly cancel out: you didn't count running trips, running two-pair, nor the possibility of a chop with a JT runout.

Lol, pardon my brainfart, of course JT isn't a chop. Welcome to 2p2, it's usually not this bad!

Also, Equilab's numbers are almost the opposite (about 52% instead of 47.4%), and I'd trust Equilab over Pokerstove. I'm using both in "Enumerate All" mode, and I didn't realize they ever disagreed.

But I calculate 53.448%, so I have to look into this further. It would surprise me if Equilab got a basic problem like this wrong, so chances are there's a goofy mistake in my math.

This, I counted the two-pair permutations instead of combinations (and used combos in the denominator). Equilab's 52% figure is correct.

No idea what's up with Pokerstove. I thought maybe it can't do 16 dead cards, so I tried calculating with fewer and still couldn't reproduce its number.

52% for Tc9c is correct:

ProPokerTools Hold'em Simulation

406 trials (Exhaustive)

board: Q87

dead cards: 2222333344445555

Hand	Pot equity	Wins	Ties
AdQd	48.03%	195	0
Tc9c	51.97%	211	0

Here's why:
- There are C(29,2) = 406 runouts to consider.
- AQ wins, if both cards are not Jacks or Fives (this happens C(21, 2) = 210 times), except when both cards are from the remaining Nines and Tens (this happens C(6, 2) = 15 times).
- So AQ wins 210 - 15 = 195 times, and T9 wins the remaining 406 - 195 = 211 times, which result in about 48% and 52%.

ProPokerTools "doesn't know" that straight < set and full house < flush.
Use CombCalc6Plus.
He gives AdQd 51.97% vs Tc9c 48.03!

The OP home game is using the standard order of full deck holdem. This is an error and is exploitable, fwiw.