What math does this use?

It uses the hypergeometric distribution, the correct model for drawing without replacement from a deck. For each combo piece it computes the chance of seeing at least one copy in the cards you have drawn, then multiplies across pieces.

Is multiplying the per-piece probabilities exact?

It is a close approximation that slightly understates the true odds, because the draws compete for the same slots. For typical 2 to 3 piece combos in a 60-card deck the error is small, usually a couple of percent.

How many cards have I seen by turn N?

On the play you have seen 7 plus (N minus 1) cards by your turn N draw step; on the draw you have seen 7 plus N. This tool applies that rule automatically based on the play or draw toggle.

Does this account for tutors or card selection?

No. It assumes blind draws. Tutors, scry, and card filtering raise your real consistency above the figure shown, so treat the result as a conservative floor.

Why run more copies of a combo piece?

Each extra copy sharply raises the odds of seeing at least one. Going from 1 to 2 copies of a key piece in 60 cards lifts the by-turn-4 odds substantially, which is why combo decks run redundancy or tutors.

MTG Combo Turn Estimator

This estimator tells you how reliably a combo deck assembles its pieces. Enter how many copies of each piece you run and the tool returns the probability that you are holding the full combo by a given turn, using the same hypergeometric math the pros use to tune consistency.

How it works

For a single combo piece with k copies in an N-card deck, the chance of drawing at least one copy within d cards seen is the complement of drawing none:

P(at least one) = 1 − C(N − k, d) / C(N, d)

where C(n, r) is the binomial coefficient “n choose r”. To hold every piece of a multi-card combo, the tool multiplies the per-piece probabilities together:

P(full combo) = Π over pieces of P(at least one of that piece)

Cards seen d depends on play or draw: on the play d = 7 + (turn − 1), on the draw d = 7 + turn.

Example and tips

A two-card combo with 4 copies of piece A and 1 copy of piece B in a 60-card deck, on the play by turn 4, has roughly a 39 percent chance per the lone B copy dominating the result. Adding a second copy of the rare piece, or a tutor that fetches it, dramatically improves the assembly odds. Because the multiply step ignores that draws compete for slots, treat the figure as a slightly conservative estimate of true consistency.