MTG Mulligan Calculator
See how often a keepable opening seven shows up under the London mulligan.
Start from a common question
Chance of finding a keepable seven
What do these numbers mean?
- Cards in deck (deck size)
- Commander usually starts at 99 cards in the library.
- Matching cards in deck (desired cards in deck)
- Enter how many lands, combo pieces, or other hits count for this test.
- Hits you want in the opener (hits wanted in opening seven)
- Use 1 when you just need to see one key card. Use 2 or more for land checks.
- Mulligans you will take (London mulligans taken)
- This controls how many seven card looks you are willing to take before keeping.
How this is calculated
Each seven-card look is scored with the hypergeometric distribution, which models drawing without replacement. The headline number then treats every look you allow as an independent chance to find the hand you want, so more mulligans always raise it — while the keep size falls by one card each time, which is the real cost the London rule charges.
Next: check raw draw odds or size your mana base.
When should you mulligan in Commander?
A common guideline is to keep hands with two to four lands and at least one early play, and to mulligan one-landers, six-plus-land hands, and all-expensive draws. Your commander and curve move that line. This is a rule of thumb, not an official rule, and the calculator above estimates how often you keep.
Why the London mulligan changes deckbuilding math
The London mulligan gives every player a full seven-card look each time they mulligan. That matters because it increases the chance of finding a functional hand compared with older mulligan rules. The tradeoff is that every mulligan shrinks the final hand you keep by one card after the decision is made. In practice, that means the real question is not only whether a good opener exists, but how many looks you are willing to spend before the smaller hand becomes too costly.
This calculator is built around that real table decision. It measures the probability of finding a seven-card look that contains your required package, then rolls that into the chance of getting there after the number of London mulligans you are willing to take. That is useful for Commander decks that care about minimum land counts, fast mana, engine cards, protection pieces, or one side of a combo setup.
Example. If your deck has ten cards that count as early acceleration and you are willing to mulligan once to look for at least one of them, use deck size 99, desired cards 10, hits wanted 1, and London mulligans taken 1. The after mulligans result shows your chance of seeing at least one accelerator across both seven-card looks.
How to interpret the numbers
The one seven-card look result is your probability before taking any mulligan. The after mulligans result shows the chance of seeing a valid seven-card look at least once across every look you allowed. If you set mulligans taken to two, the tool assumes you are willing to see as many as three different sevens before settling on the last acceptable one. The final keep size reminds you what that choice costs.
This framing matters because players often overestimate how much one more mulligan helps. Sometimes going from zero to one is a big jump in consistency. Sometimes the move from one to two is modest and does not justify starting a card lower. The answer depends on deck speed, redundancy, and whether your pod gives you enough time to recover from card disadvantage.
If your question is really about raw draw odds instead of London mulligans, the hypergeometric calculator shows the same probability model without the keep-decision wrapper. If the opener depends heavily on early lands, the mana base calculator is the natural companion. For a full mulligan-aware run against a specific card and turn, the cEDH Goldfish Simulator is a Commander goldfish simulator built for target-card timing, including whether your deck casts Rhystic Study by turn two.
Worked Commander examples
A midrange deck may care about opening with at least two lands and one early accelerator. A combo deck may care less about raw lands and more about seeing one tutor or one piece of selection. A stax deck may care about one early hate piece plus enough mana to cast it. In each case, the trick is to translate the opener you want into a count of hits in the deck and then ask how often the opening seven actually contains it.
Suppose your deck has 36 lands and you want to know how often you see at least two in the opener. Enter desired cards 36 and hits wanted 2. Then compare zero, one, and two mulligans. You may discover that a land count you thought was safe actually leans on aggressive mulliganing to feel good in practice. That is valuable because it exposes hidden deckbuilding risk instead of letting it hide inside table memory.
On the other hand, if the deck is full of cantrips, filtering, and modal cards, the calculator may show that you do not need to mulligan as aggressively as expected. Saving one card can matter more than chasing a slightly cleaner seven.
Use mulligan math to support real decisions
This tool is best used to sharpen keep standards, not replace judgment. If a hand technically meets the math threshold but cannot cast spells of the correct color, the calculator will not save it. If a combo hand has one piece but no protection in a hostile pod, the right call may still be a mulligan. Numbers give you the baseline rate. Experience tells you when the table context changes the answer.
The best use case is comparison. If adding one land or two extra one-mana plays lets you mulligan less often, that may be worth more than a flashy upgrade elsewhere. If a narrow package only becomes reliable after two mulligans, the deck may be asking too much of the opening hand. Those are exactly the decisions this page is meant to clarify.
Want the full Commander deck audit?
Check your bracket pressure, Game Changers, price drivers, mana curve, lands, ramp, draw, interaction, and cards to review in one place.
Mulligan calculator FAQ
Does this assume I always take every mulligan listed?
It assumes you are willing to see up to that many new seven-card looks. In a real game you can always stop earlier if a keepable hand appears first, so the result is best read as your maximum search window rather than a forced line.
Why does the final keep size go down even though every look is seven cards?
That is the core London mulligan rule. You always draw seven first, then put a number of cards equal to mulligans taken on the bottom after you choose the hand to keep. The page shows that cost because consistency and hand size are linked.
Can I use this outside Commander?
Yes. Change deck size to match the format and keep the same mulligan logic. The math is portable even though Commander is the most common use case on this site.