MTG Deck Mana Audit Tool

Paste a decklist or link a Moxfield, Archidekt, or TappedOut deck. The tool pulls real card data from Scryfall, counts your actual mana sources, and checks every colored-cost spell in the deck against the exact hypergeometric distribution — not just your lands, your whole deck at once.

What this tool actually checks

The mana base calculator answers one spell at a time: given this many sources, how reliably do I cast this specific cost by this specific turn? That is exactly right when you already know which spell you are worried about. Most decks have fifteen or twenty colored-cost spells, though, and checking each one by hand is tedious enough that nobody actually does it.

This tool automates that process. Paste your list, and it resolves every card against Scryfall, tallies how many sources of each color you actually run — lands, signets, talismans, dorks, anything that produces mana counts — and then runs the same hypergeometric math against every colored spell in the deck, on the turn its mana value suggests you would normally cast it. The result is a ranked table: which spells are safe, which are borderline, and which ones will strand you in hand more often than you would like.

How to read the results

The table is sorted worst-first. Each row shows the spell, its mana cost, the turn it was evaluated on (its mana value, on the play), the odds of having enough sources of its hardest color by that turn, and a suggested fix — how many more sources of that color would push it to a 90% success rate. A "Worst offenders" callout above the table pulls out anything under 75% so you do not have to scroll through the full list to find the real problems.

The three charts give context for why the numbers look the way they do. The mana curve shows how your spells are distributed by cost — a pile of four-drops explains why turn-4 casts feel inconsistent even with a reasonable source count. The sources-by-color chart shows your actual color balance at a glance. The card-type chart shows the overall shape of the deck.

Multicolor spells: which color is the bottleneck

For a spell that needs more than one color — say a commander that costs WB — the tool checks each color's pip requirement independently against your actual source count for that color, and reports the worse of the two. This is Frank Karsten's approximation for multicolor costs: it is not the exact joint probability of having both colors at once, but it identifies the real bottleneck color correctly in the overwhelming majority of decks, and it is far more useful than either ignoring multicolor costs or drowning the table in exact-but-unreadable joint distributions.

What this tool does not model

A few honest simplifications, matching the standalone calculator:

• Tapped lands aren't flagged separately. A tapped dual and an untapped dual count the same as a source. A land that consistently enters tapped is worth less than the numbers here suggest, especially in aggressive decks.
• Mana rocks and dorks count 1:1 with lands. A Signet is a real source of its colors but comes online a turn later than a land on curve. The count is accurate; the timing nuance is not modeled.
• Hybrid and Phyrexian mana are simplified. A hybrid pip like W/U is scored against whichever color you have more sources of, since either can pay it. Phyrexian pips are treated as effectively free, since they can be paid with life.
• Mulligans aren't modeled. Every probability assumes a 7-card opening hand kept as drawn, same as the standalone calculator.

Getting the deck size right

Linking a Moxfield or Archidekt deck gets the commander and sideboard excluded automatically, so the library size used in the math is correct without you doing anything. TappedOut's export doesn't separate the commander from the rest of the list, so TappedOut links work like pasted text: the tool looks for a Moxfield-style *CMDR* tag or an explicit Commander/Sideboard section header — otherwise, paste just your 99-card (or 60- or 40-card) library on its own for the most accurate numbers.

FAQ

Does this tool support Commander decklists?

Yes. Paste a 99-card list or link a Moxfield, Archidekt, or TappedOut Commander deck. Moxfield and Archidekt links detect the commander automatically and exclude it from the library count. TappedOut's export doesn't separate the commander from the rest of the list, so for TappedOut links (and for pasted text) the tool looks for a Moxfield-style *CMDR* tag or a Commander section header; otherwise, paste just your 99-card library for the most accurate deck size.

Do mana rocks and dorks count as sources?

Yes, counted 1:1 with lands. Any card Scryfall lists as producing a color — lands, signets, talismans, dorks, and other rocks — counts toward that color's source total. A Signet effectively comes online a turn later than a land on curve, but for this tool's purposes it counts the same way lands do; keep that in mind for very ramp-heavy decks.

Why does a card show as at risk even though it only needs one pip?

A single colored pip is still a real requirement, and if that color is thin in your deck — a light splash with only six or seven sources, for example — even a one-pip spell can miss on curve more often than you'd expect. The odds shown account for your actual source count and the turn you'd normally cast the card, not just the pip count.

Which deck-building sites are supported?

Moxfield, Archidekt, and TappedOut links are supported today. All three rely on undocumented exports, so if a link fails to load, the site may have changed its format — paste the decklist as plain text instead and it will work the same way. More sites may be added later.