Mana Base Math for Commander: How Many Lands and Colored Sources You Need
In short: with 37 lands you hit your fourth land drop on turn four only about two times in three. Colored sources matter even more than total lands.
- 36 to 38 lands gives roughly an 80% chance of three lands by turn three, before counting ramp or mulligans.
- For a one-pip spell on turn two you want about 19 to 22 sources of that color. For a double-pip spell on turn three, about 29 to 33.
- Cheap mana rocks and dorks smooth out these numbers, which is why low-curve decks can run fewer lands.
- All numbers below come from the hypergeometric distribution for a 99-card library.
Most land-count advice is a rule of thumb. That is fine, but if you build a lot of decks it helps to know what the numbers actually look like. This guide does the math for a 99-card library so you can make informed trade-offs instead of guessing.
The assumptions
- 99 cards in the library. Your commander starts in the command zone, so it does not count.
- You draw on turn one. In multiplayer Commander nobody skips their first draw, so by turn three you have seen ten cards.
- No mulligans, no ramp. Mulligans and card draw improve these odds, so treat the numbers as a floor.
- A source is a land that taps for the color. A dual land counts for both of its colors.
How often you hit your land drops
This table shows the chance of having at least that many lands by that turn, plus the chance of flooding with seven or more lands in your first thirteen cards.
| Lands | 2 by turn 2 | 3 by turn 3 | 4 by turn 4 | 5 by turn 5 | Flood risk |
|---|---|---|---|---|---|
| 34 | 88% | 74% | 56% | 39% | 10% |
| 36 | 91% | 78% | 62% | 46% | 14% |
| 37 | 92% | 80% | 65% | 49% | 16% |
| 38 | 93% | 82% | 68% | 52% | 18% |
| 40 | 94% | 85% | 73% | 58% | 22% |
Two things stand out. First, every extra land adds only a few percent at each step, so the difference between 36 and 38 is smaller than many players think. Second, the fourth and fifth land drops are far from guaranteed even with 38 lands. That is exactly why ramp and card draw are so important in Commander.
Colored sources by mana requirement
The more colored pips a spell has, and the earlier you want to cast it, the more sources of that color you need. These are the sources needed for an 85% and a 90% chance.
| You want to cast | 85% chance | 90% chance |
|---|---|---|
| 1 pip by turn 1 | 21 | 24 |
| 1 pip by turn 2 | 19 | 22 |
| 1 pip by turn 3 | 17 | 20 |
| 2 pips by turn 2 | 32 | 36 |
| 2 pips by turn 3 | 29 | 33 |
| 2 pips by turn 4 | 27 | 30 |
| 3 pips by turn 4 | 37 | 40 |
| 3 pips by turn 5 | 34 | 38 |
A double-pip three-drop needs around 29 to 33 sources of one color. In a two-color deck with 37 lands that is only realistic if most of your lands produce that color, which is why heavy pips in your off color are a real cost.
What this means for your deck
- Mono-color decks. Every land is a source, so colored mana is rarely a problem. Spend your land slots on utility lands instead.
- Two-color decks. Aim for at least 20 to 22 sources of each color, which needs plenty of dual lands. Keep double pips mostly in your main color.
- Three-color decks. Getting 20 sources of each color requires many tri-lands, fetches or duals. Lean on early fixing rocks and keep heavy pips to a minimum.
- Four and five colors. Plan for slower starts. Ramp spells that fetch basics of any type and mana rocks that make any color do a lot of the work.
Ramp, card draw and mulligans
A common rule of thumb is to count each two-mana rock or one-mana dork as roughly half a land when deciding your total. It is not exact, but it explains why a deck with ten cheap ramp pieces can safely run 34 or 35 lands while a deck with none should be closer to 38.
Mulligans matter too. With 36 to 38 lands, about 80% of seven-card hands contain two to five lands. Most playgroups allow a free first mulligan, which pushes the chance of a keepable hand even higher.
Frequently asked questions
Should I count modal double-faced cards as lands?
Count them as about half to three quarters of a land. They hit the land drop when you need it, but often enter tapped and cost you the spell side.
Do fetch lands count as sources for every color they can find?
Yes, for the colors of the lands they can actually fetch in your deck. A fetch that can find a dual land in your colors counts for both.
Is 40 lands ever right?
For landfall decks or decks with lots of expensive spells and few rocks, yes. You accept more flooding in exchange for consistent big turns.