What is a mana curve in Magic?

A mana curve is the distribution of your deck's cards by converted mana cost (mana value). A smooth curve weighted toward cheap spells lets you cast something useful on most turns, which is one of the biggest drivers of a deck's consistency.

How is average CMC calculated?

The tool sums the mana value of every non-land card and divides by the number of spells. The 7+ bucket is counted as exactly 7, so the average is a slight underestimate for very top-heavy decks. Lands are excluded because they have no mana value.

How many lands should my deck run?

The recommendation starts from the standard ratio for your format (about 42.5% for 40-card Limited, 40% for 60-card Constructed) and nudges it up or down by one or two lands based on your average mana value. Higher curves want more lands; aggressive low curves can run slightly fewer.

What does a good mana curve look like?

For most aggressive and midrange decks the peak sits at one or two mana, tapering off toward higher costs. Control decks can carry a higher curve because they expect to reach the late game. There is no single ideal shape — it depends on your deck's plan.

Does this account for X spells or alternate costs?

No. Cards with X in their cost, alternate casting costs, or mana value reducers are entered at whatever value you decide best represents them. The tool works purely from the buckets you input, so use your judgement for unusual cards.

MTG Mana Curve Analyzer

The mana curve is the single most useful picture of a Magic deck’s early-game consistency. This analyzer turns your card counts into a histogram, an average converted mana cost (CMC), and a recommended land count so you can spot whether your deck is too top-heavy, too cheap, or mis-landed before you ever shuffle up.

How it works

You enter the number of non-land spells at each mana value from 0 through 7+, plus your current land count. From those numbers the tool computes:

Total spells — the sum across every mana-value bucket.
Average CMC — the spell-weighted mean mana value. Each bucket count is multiplied by its mana value (the 7+ bucket counts as 7), summed, and divided by the total number of spells. Lands are excluded because they have no mana value.
Recommended lands — the tool starts from the standard land ratio for your deck size (roughly 42.5% for 40-card Limited and 40% for 60-card Constructed) and adjusts by one to two lands based on your average CMC. Decks with an average CMC of 3.0 or higher want more lands; very cheap curves around 2.0 or below can shave one.

The histogram bars are scaled to the tallest bucket so the shape of your curve is easy to read at a glance.

Tips and example

Suppose a 40-card Limited deck has this spell distribution: 0:0 1:8 2:9 3:7 4:4 5:2 6:1 7+:1. That is 32 spells with an average CMC of about 2.6. The recommended land count comes out near 17, which matches the long-standing Limited rule of thumb. If you only have 15 lands in the list, the tool warns you are below the recommendation and at risk of mana screw.

A few practical notes:

A peak at one or two mana usually signals a healthy aggressive or midrange curve.
If your spells plus lands do not add up to your chosen deck size, the tool flags it so you can rebalance.
Treat the land recommendation as a starting point. Cheap card draw, cycling lands, and mana ramp all let you trim lands slightly — pair this tool with the MTG Land Count Optimizer for a more detailed estimate.