Movement speed

The Movement Speed affects the rate at which a champion travels across a map. One movement speed point translates to one game distance unit traveled per second (as a frame of reference, Annie's basic attack has a range of 625 game distance units). Each Champion begins the game with a particular base move speed. That base move speed can be increased in several ways.

Movement speed ranges from 's 300 units per second to 's 330 units per second.

Calculation
There is a soft cap for both high and low speed, based on marginal return brackets:

Lower soft cap has still to be found.
 * If calculated speed is over 415, only 80% of the excess is given.
 * If calculated speed is over 490, then 80% of the 416-490 bracket is given (total comes to 475), and 50% of the amount above 490 is added to that.

Slowing effects can stack, but only the strongest slowing effect from each source (item, ability, neutral buff) is taken into account at any given time; the others from that type are ignored.

Boots (Base Movement Speed)
A champion can obtain one of the following base movement speed bonuses by purchasing boots from the shop. These effects are unique, meaning that if a champion has more than one bonus to their base movement speed, they will only receive the highest bonus. Note that bonuses are flat amounts so the percentage increase depends on the base movement speed of the champion. There are several items granting a base movement speed bonus:
 * Movement Speed 1 increases the base movement speed of a champion by 50. (around +16%)
 * Movement Speed 2 increases the base movement speed of a champion by 70. (around +22%)
 * Movement Speed 3 increases the base movement speed of a champion by 90. (around +29%)
 * Movement Speed 5 increases the base movement speed of a champion by 130. (around +40%)
 * Enhanced Movement 1. 350 Gold.
 * Enhanced Movement 2. +25 Armor, +12% Dodge Chance. 850 Gold.
 * Enhanced Movement 2. 15% Cooldown Reduction 900 Gold.
 * Enhanced Movement 2. +25% Attack Speed. 920 Gold.
 * Enhanced Movement 2. +20 Magic Penetration. 1100 Gold.
 * Enhanced Movement 2. +25 Magic Resistance, Unique Passive: Reduces the duration of stuns, slows, taunts, fears, snares, sleeps, and immobilizes by 35%. 1200 Gold
 * Enhanced Movement 3. 1000 Gold.
 * Enhanced Movement 2. Passive: When out of combat for 5 seconds the effect of these boots is increased to Enhanced Movement 5. 1000 Gold.

Items
Increases the movement speed of a champion by adding a percentage of their base move speed.
 * +8% Movement Speed. +76 Magic Resistance, +40 Health Regen per 5 sec, UNIQUE Passive: Restores 0.35% of your champion's health every second. 2610 Gold.
 * +10 Attack Damage, UNIQUE Passive: Your champion gains 5 damage per stack, receiving 2 stacks for a kill or 1 stack for an assist. This effect can stack 20 times; you lose a third of your stacks if you die. At 20 stacks, your champion's movement speed is increased by 15%. 1369 Gold.
 * +8% Movement Speed. +20% Attack Speed, +10% Critical Strike. 1195 Gold.
 * +7% Movement Speed. +350 Mana, +80 AP, +30 Magic Resist, UNIQUE Passive: 100% chance when an ability is used that your next physical attack deals an additional 100% of your Ability Power in damage. This effect has a 3 second cooldown. 3470 Gold.
 * +15% Movement Speed. +55% Attack Speed, +30% Critical Strike. 2895 Gold.
 * +12% Movement Speed. +30 Attack Damage, +30 Ability Power, +30% Attack Speed, +15% Crit Chance, +250 Health, +250 Mana, UNIQUE Passive: 25% chance on hit to slow the target by 35% for 2.5 seconds; on cast, increases your base Attack Damage by 150% for one attack. 4070 Gold.
 * +30 Attack Damage, +15% Critical Strike, UNIQUE Passive: Reduces cooldowns by 15% and +20 armor penetration, UNIQUE Active: Gives 20% movement speed and +50% attack speed for 4 seconds. Attacking enemy units with melee attacks increases the duration by 2 to a maximum of 8 seconds. 60 second cooldown. 2687 Gold.
 * +330 Health, +30 Health Regen per 5 sec +15 Mana Regen per 5 sec. Unique passive: Reduces ability cooldowns by 15%. Unique active: Nearby champions gain 40% movement speed for 3 seconds (60 second cooldown) 2200 Gold.

Summoner Spell

 * Your Champion ignores unit collision and moves 27% faster for 14 seconds. mastery increases the movement speed of your Ghost spell by 6% and its duration by 1.5 seconds.
 * revives your champion instantly at the spawning pool and increases movement speed by 225%, diminishing to normal over 12 seconds. 

Mastery

 * Increases your base movement speed by (1/2/3)%. (Note: Despite the description, this doesn't affect base movement speed and simply works like other percentage bonuses.)

Runes

 * Quintessences of Swiftness increase movement speed 1.5% each.
 * Quintessence of the Speedy Specter increases speed 1.39% each. (Tier 2.5)

Hero Abilities

 * grants him (16 / 20 / 24 / 28 / 32)% increased movement and (30 / 38 / 46 / 54 / 62)% attack speed for 8 seconds.
 * grants her (15 /17.5 / 20 / 22.5 / 25)% increased movement if she hits a champion.
 * grants her (50 / 75 / 100)% attack speed and (20 / 25 / 30)% movement speed for 10 seconds.
 * grants him (15 / 20 / 25 / 30 / 35)% increased movement for 2 seconds.
 * creates a directional draft for 5 seconds which increasing the movement speed of allies passing through it by (20 / 25 / 30 / 35 / 40)%.
 * passive increases the movement speed of all allied champions by 3%, even when she is dead.
 * passively increases her movement speed by (8 / 10 / 12 / 14 / 16)% and enables her to pass through units.
 * increases her movement speed and an ally's movement speed by (10 / 12 / 14 / 16 / 18 / 20)%. The amount is doubled if she uses a charge on the spell.
 * grants him a flat bonus to movement equal to the flat part of his speed (after any multiplication is calculated) and the ability to move through units for 4 seconds.
 * steals (14 / 17 / 20 / 23 / 26)% movement speed from the target for 4 seconds.
 * passive grants her an additional 25 movement speed after not taking any damage for 7 or more seconds, increasing each second up to 70 maximum bonus speed.
 * grants her 20 movement speed in cougar form.
 * grants an allied unit (25 / 35 / 45 / 55 / 65)% increased attack speed and (11 / 12.5 / 13 / 14.5 / 15)% increased movement speed for 15 seconds. If cast on an ally, Nunu also gains the effect of Bloodboil.
 * grants her (17 / 19 / 21 / 23 / 25)% increased movement speed for 5 seconds when activated.
 * grants him an increasing bonus to movement speed while active.
 * grants him (35 / 50 / 65) increased movement speed while active.
 * grants her and nearby allies 25% extra movement speed and a percentage of attack speed (a third for her allies) for 15 seconds.
 * grants nearby allied champions bonus movement speed (8 / 11 / 14 / 17 / 20). On activation, it grants an additional burst of speed (6 / 8 / 10 / 12 / 14)% for 1.5 seconds.
 * increases his movement speed by (15 / 20 / 25 / 30 / 35)%. If Teemo gets hit by a champion or turret while Moving Quick, he gets knocked out of it.
 * infects a target location with his curse for 8 seconds, granting (20 / 30 / 40 / 50 / 60)% attack speed, (20 / 25 / 30 / 35 / 40)% movement Speed, and (20 / 25 / 30 / 35 / 40)% CC reduction while on it.
 * grants him (15 / 18 / 21 / 24 / 27)% increased movement speed for (2 / 2.5 / 3 / 3.5 / 4) seconds upon activation.
 * senses enemy champions under 50% life within (1500 / 2300 / 3100 / 3900 / 4700) distance of him; while he detects a low-health enemy, he gains (20 / 25 / 30 / 35 / 40)% increased movement speed.
 * increases an allied champion's movement speed by 55% for (2.5 / 3.25 / 4 / 4.75 / 5.5) seconds.
 * has an un-noted movement speed increase of approximately 35%.

Items

 * UNIQUE Active: Deals 150 magic damage and slows the target champion by 50% for 3 seconds (400 range). 60 second cooldown.
 * UNIQUE Passive: Physical attacks slow enemy's movement speed by 40% (30% for ranged) for 2.5 seconds.
 * UNIQUE Active: Deals 300 magic damage and slows the target champion by 50% for 3 seconds (700 range). 60 second cooldown.
 * UNIQUE Passive: 25% chance on hit to reduce your target's Movement Speed by 30% for 2.5 seconds.
 * UNIQUE Passive: 20% on being hit to slow the attacker's movement and attack speed by 35% for 3 seconds
 * UNIQUE Active- Slows movement speed and attack speed of surrounding units by 35% for 2 second + 0.5 seconds for each 100 Armor and Magic Resist. 60 second cooldown.
 * Your spell damage slows the target's movement speed by 35% for 1.5 seconds (15% for multi-target spells). (NOTE: although it isn't described as unique, only one effect will be counted.)
 * UNIQUE Passive: 25% chance on hit to slow the target by 35% for 2.5 seconds.
 * Passive: 20% chance on being hit to slow the attacker's movement and attack speeds by 35% for 3 seconds.

Summoner Spell

 * It decreases the movement speed of an enemy by 40%, (auto/basic) attack damage by 70%, and ability/item damage by 35% for 3 seconds. mastery will lenghten its duration to 3.5 seconds and will also add the effect of reducing the enemy's armor and magic resistance by 10 for the duration.

Hero Abilities

 * slows units within its effect by (14/18/22/26/30)%.
 * slows effected units' movement speed and attack speed by 20% for 2.5 seconds, refreshing while the remain in the effect.
 * causes each of Ashe's basic attacks to slow her target's movement speed by (15/20/25/30/35)% for 2 seconds while active.
 * Her also applies her current level of Frost Shot.
 * Her slows in an area around contact units at an unknown amount.
 * slows effected units' movement speed by 50% for (1/1.25/1.5/1.75/2) seconds.
 * slows effected units' movement speed by (15/20/25/30/35)% for 2 seconds.
 * slows the movement speed of targets facing away by 60% for 2 seconds.
 * slows effected units' movement speed by 60% for 3 seconds.
 * slows the target's movement speed by 40% for 2 seconds.
 * slows effected units' movement speed by (24/28/32/36/40)% for 2.5 seconds.
 * slows effected units' movement speed by (35/45/55)% for 1.25 seconds.
 * slows effected units' movement speed by 35% for 2.5 seconds.
 * cause his turrets' shots to slow movement speed by (20/25/30)%.
 * slows the target's movement speed by 60% for (1/1.25/1.5/1.75/2) seconds if the target has a lower Health % than she does.
 * slows an enemy's movement speed by (24/30/36/42/48)% for 4 seconds.
 * slows an enemy's movement speed by 30% while in its effect.
 * decreases the target's movement speed by (10 / 12 / 14 / 16 / 18 / 20)% if cast on an enemy. The amount is doubled if she uses a charge on the spell.
 * slows effected units' movement speed by (40/50/60/70/80)% for 5 seconds.
 * slows effected units' movement speed by (30/35/40/45/50)% for 3 seconds.
 * slows the target's movement speed by 25% for 4 seconds. Kayle deals increased damage to the target while it's slowed.
 * slows an enemy's movement speed by (28/36/44/52/60)% while in its effect.
 * slows the target's movement speed by 25% for 2 seconds.
 * slows an enemy's movement speed by (20/24/28/32/36)% while in its effect.
 * will steal a percentage of an enemy's movemente speed.
 * slows an enemy's movement speed by (20/25/30/35/40)% while in its effect.
 * slows nearby enemies' movement speed by 20% while active.
 * slowing their movement speed and attack speed by 35% and further reducing it by (3/6/9/12/15)% each second for 5 seconds.
 * slows the target's movement speed by (40/45/50/55/60)% for 4 seconds.
 * slows enemies' movement speed by 41.2% while in its effect.
 * slows the target's movement speed by (24/28/32/36/40)% for 2.5 seconds.
 * slows effected units' movement speed by (28/36/44/52/60)% for 4 seconds.
 * slows the target's movement speed by (20/22.5/25/27.5/30)% for 2 seconds.
 * slows effected units' movement speed by (35/45/55/65/75)% for 5 seconds.
 * slows the target's movement speed by (20/23/26/29/32)% for 3 seconds.
 * slows effected units's movement speed by (30/40/50)% for 4 seconds when triggered.
 * slows effected units's movement speed by 60% for 2.5 seconds.
 * slows enemies' movement speed by (25/30/35/40/45)% while near the summoned pillar.
 * slows effected units' movement speed by (30/37.5/45/52.5/60)% for 4 seconds. (Only slows enemies facing away.)
 * slows nearby enemy champion by 30%, plus 6% per stack of applied to them.
 * causes all of his attacks and abilities to slow effected units' movement speed by (20/25/30/35/40)%.
 * slows the target's movement speed by 40% for 4 seconds.
 * slows the charged target and nearby units by (20/25/30/35/40)% for 1.75 seconds.
 * reduces an enemy champion's movement speed by 55% for (2.5 / 3.25 / 4 / 4.75 / 5.5) seconds.