Updated 1 Page Monster Creation Reference for 5th Ed.

Changes are Bold

A Creature with a CR below 1 gets 1 free benefit. CR 1-2 Gets 2 Benefits, 3-4 get 4, 5-6 get 6 and so on.
In all cases, round up.
Armor Class
AC = 12.5 + .4* CR
Hit Points
HP = 13.75*CR +10
Speed:
CR/2 points to be spend 1: 30 feet of a given movement type.
Ability Scores
Ability Bonuses 1.33 *CR
Saving Throws
having any saving throw is worth one benefit, as is every 3 points assigned to that saving throw.
Skills
A monster gets 3 + 1*CR skill points for free.
Vulnerabilities
Each thing a monster is Vulnerable to is worth a penalty.
Resistances and Immunities
Each resistance or immunity is worth 1 benefit.
Perception modes:
Normal, Darkvision no cost. Normal 1 penalty to lack
Blindsight, Truesight Costs one benefit to have.
Melee to Hit Bonus
Hit Bonus = 3+ CR/2
Damage
Melee damage is 6 + 2.7*CR
Ranged:
If a creature has no melee attacks, calculate ranged attacks as melee attacks.
If a creature has melee attacks, ranged attacks are one benefit per 3 dmg and 1 per 2 to hit
Abilities This is things like the ability to use a poison, or 5 spell levels of spell casting, or attacks that automatically gain advantage.
Saving throws
If a special ability allows a saving throw, the DC is 10 +CR/4. Count it as a bonus or penalty for every 2 points over under this number.

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Compiled Averages: Monsters from Hoard of the Dragon Queen and the Starter Set (I should add the PHB stuff, but maybe later. I’ll probably do that over the month until the next book comes out)

 CR Number XP ac hp speed points total stat bonus points from saves skills vulnerable resistance immunity blind sight dark vision true sight melee hit bonus avgdmg ranged hit points from ranged benefits
0 3 11 4 1.333333 -0.66667 0 0 0 0 0 0 0 0 2 2 0 0 0
0.125 9 13.33333 5.888889 1.222222 -1.44444 0 3 0.222222 0 0.222222 0.111111 0.333333 0 3.555556 4.333333 0.888889 0.222222 0.777778
0.25 14 11.35714 13.5 1.5 -4.14286 0.071429 2.071429 0.214286 0.214286 1 0.142857 0.571429 0 3.5 6.071429 1.142857 0.428571 1.785714
0.5 10 13.6 16.9 1.3 2.1 0 4.2 0 0.6 1.3 0.2 0.4 0 3.8 7.5 2.4 1.2 1.7
1 9 13.22222 26.55556 1.333333 1.888889 0.555556 8.777778 0.111111 0.888889 1.555556 0.666667 0.666667 0 3.555556 8.444444 2 0.888889 2.555556
2 13 12.84615 40.92308 1.846154 1.076923 0.307692 4.615385 0.230769 1.384615 2 0.076923 0.615385 0 4.384615 10.69231 1.538462 0.538462 2.384615
3 9 14.66667 51.33333 1.444444 7.777778 0.333333 4.777778 0.111111 0.888889 1.555556 0 0.777778 0 4.888889 23.11111 1.444444 0.833333 3
4 2 16.5 50 2 5.5 0 5.5 0 3 7.5 0.5 0.5 0 3 9 0 2.5 4
5 6 15.66667 99.83333 6.166667 4.833333 1 3.833333 0.666667 2 2.166667 0.166667 0.833333 0 6.833333 25.33333 0 0 4.666667
6 2 12.5 75 2 4 2 8 0 0 0 0 0.5 0 6 20.5 3.5 0 4.5
7 1 17 126 2 13 5 16 0 0 0 0 1 0 9 38 9 4 4
8 2 16.5 107 3.5 10 5 21 0 0.5 1 0.5 0.5 0 7 21.5 3.5 0.5 8
10 1 17 178 1 1 0 0 0 0 11 0 1 0 10 38 0 0 5
13 2 17 172 4.5 17 8.5 16 2 2 0.5 0.5 1 0 10 35 0 0 12.5
16 1 19 225 6 22 10 17 0 0 1 1 1 0 12 48 0 0 16