Build Commander
Your commander is the one card in the deck you're guaranteed to draw. Its mana value, and commander tax on top of it, should shape your land and ramp count more than the rest of your curve alone.
Every card in your 99 might or might not show up in your opening hand. Your commander always shows up, because it starts in the command zone and you can cast it whenever you have the mana. That makes its own mana value a special case when you're setting your land count, not just one more data point in your curve.
A deck built around a 2-drop commander is guaranteed a strong turn two if it wants one, and its land count only needs to support the rest of the deck's curve. A deck built around a 6-drop commander is making a commitment: it needs to reliably reach 6 mana, and then reach it again after the commander gets removed, which is where commander tax comes in.
Comprehensive Rules · Rule 903.8
"A player may cast a commander they own from the command zone. A commander cast from the command zone costs an additional {2} for each previous time the player casting it has cast it from the command zone that game. This additional cost is informally known as the 'commander tax.'"
In plain terms: your commander costs 2 more every time you recast it from the command zone after the first. A 4-mana commander is 6 to recast once, 8 the second time, 10 the third. Against a table that's regularly removing your commander, an expensive one becomes genuinely difficult to recast without a real ramp package behind it, which is exactly why a higher-mana-value commander should push your ramp count up, not just your land count.
A commander at 2-4 mana value. Reasonably reachable off a normal land count and curve. Build your land count off the rest of your deck's curve as usual, see how many lands to run for the general target.
A commander at 5-6 mana value. Push toward the higher end of the land-count range (38+), and make sure your ramp package is genuinely strong (10+ pieces), since you'll want to hit that cost more than once across a long game.
A commander at 7+ mana value. Treat ramp as close to mandatory rather than optional. A deck built around a very expensive commander that skimps on ramp is a deck that casts its commander once, loses it, and never gets to cast it again for the rest of the game.
Not directly, since your land count is mostly about your whole deck's curve rather than one card. What it does mean is you can afford to hold a land back or take a turn off from casting your commander without it setting your whole game plan back, which gives a cheap-commander deck a little more flexibility in exactly how many lands it wants.
Commander tax adds 2 to your commander's cost each time it's cast from the command zone after the first, so a commander that dies or gets bounced repeatedly gets meaningfully more expensive to recast. A higher land count, or a stronger ramp package, is what keeps a recast commander affordable in the mid-to-late game instead of stranded in the command zone.
Yes, more than it should change your land count specifically. A 6+ mana value commander wants a heavier ramp package (8-12+ pieces) to reliably reach that cost on a normal curve, and to still afford the recast after commander tax the second and third time.
Cheap, generally. A commander that costs 2-4 mana comes down reliably and repeatedly without needing your whole deck built around getting there, which is one reason several beginner-friendly commanders share that trait. See best commanders for beginners for specific picks.
The Deck Lab knows your commander's mana value the moment you pick it, and measures the rest of your build against it.
Open the Deck Builder