Renew: which rank to use

Priest · Holy · 10 ranks, 4 learned by level 30.

At level 30 with 45 healing power, Renew rank 1 gets the most healing per mana; rank 4 does the most healing per second.

Rank 1 stays the most mana-efficient from 0 to 300 healing power.

Every rank at level 30 with 45 healing power

Rank	Healing per cast	Mana	Healing per mana	HPS	Mana lasts
Rank 1 (level 8)	90 (90–90)	30	3.00	60	1 min 15 s
Rank 2 (level 14)	120 (120–120)	65	1.85	80	35 s
Rank 3 (level 20)	170 (170–170)	105	1.62	113.3	21 s
Rank 4 (level 26)	205 (205–205)	140	1.46	136.7	16 s

HPS counts the global cooldown. Mana lasts: casting only that rank from 1,500 mana.

Rank 1: 90 healing for 30 mana in Forever instead of 70 for 30 in Classic Era (spell power share 1.000 instead of 0.550).
Rank 2: 120 healing for 65 mana in Forever instead of 135 for 65 in Classic Era (spell power share 1.000 instead of 0.775).
Rank 3: 170 healing for 105 mana in Forever instead of 220 for 105 in Classic Era (spell power share 1.000 instead of 1.000).
Rank 4: 205 healing for 140 mana in Forever instead of 290 for 140 in Classic Era (spell power share 1.000 instead of 1.000).

From the client, for each rank: base damage or healing and its range (SpellEffect base points and variance), the extra per level up to the rank's max level, the spell power share (coefficient), mana cost, cast time, duration, global cooldown and cooldown.
No downrank penalty in the Forever client. Classic Era's client puts a penalty for spells learned before level 20 inside the coefficient (Shadow Bolt rank 1: 0.14); Forever's client gives the full share (0.486), for 80 low-level ranks across the classes. Anything else would be on Blizzard's servers, so the calculator shows Classic's rules only as Speculation.
Speculation: crits count only on direct hits, at 150%, as in Classic; the example gear (1.5 spell power per level) is not client data.