Turn rate

Turn rate is the speed at which a unit can turn. When moving to a location, a unit first turns to face that location, then begins walking. Similarly, when targeting another unit with an attack or spell, a unit first turns until it is facing the target, and then continues with the action. A unit only starts moving, or only starts casting a spell on a targeted area or point when the target is within 11.5° angle in front of the ordered unit. This can make kiting more difficult, as the hero has to spend time turning towards and away from the target with each attack.

Every unit has a base turn rate, which can be lowered by some abilities. The vast majority of heroes have a turn rate between 0.4 and 0.6, meaning it takes between 0.15 and 0.23 seconds for the hero to make a 180 degree turn.

Mechanics
Turn rate is expressed in radians per 0.03 seconds. A 180 degrees turn is the same as π (3.14) radians.

0.03π divided by the turn rate of the unit equals to the time it takes to turn 180 degrees. A turn rate slow is directly applied to the base turn rate. For example, a turn rate slow of 70% on a unit's 0.5 base turn rate lowers the unit's actual turn rate to [0.5 (1-0.7)] = 0.15.

(0.03π / T = t, where T = turn rate and t = the time it takes to turn around).

Examples:


 * 1) A hero with a turn rate of 0.6 takes roughly 0.157 seconds to turn 180 degrees. (0.03π / 0.6)
 * 2) A hero with a turn rate of 0.4 and a turn rate slow of 70% takes roughly 0.785 seconds to turn 180 degrees. (0.03π / (0.4 * 0.3))
 * 3) A hero with a turn rate of 1.0 and a turn rate slow of 70% takes roughly 0.314 seconds to turn 180 degrees. (0.03π / (1.0 * 0.3))
 * 4) A hero with a turn rate of 0.4 and turn rate slows of 70% and 50% takes roughly 1.571 seconds to turn 180 degrees. (0.03π / (0.4 * 0.15))

However, a unit does not immediately start turning at the highest rate it can turn. The turn rate ramps as the unit starts turning, reaching the unit's max turn rate after a certain amount of time. The rate at which the turn rate ramps up is unknown.

If a unit starts turning due to an ability or item cast order (by targeting a point, area or unit which is not within the required 11.5° facing angle), the turning cannot be canceled by a move, attack or a new spell cast order. Any command ordered while turning due to a spell cast order gets queued up and executed once the spell is cast. In order to cancel the spell or ability cast, the player must issue a stop or halt command, in the same way how to cancel spell during its cast animation. This is to prevent accidental canceling of casts due to fast clicking. Issuing a stop or halt command does not stop the unit from turning if it has already started to turn, but stops the order which initiated the turning. This allows for example Templar Assassin to turn during Meld without canceling the ability, as long as the move command is stopped before the targeted point is within the required angle.

Turn rate comparison
Below is a comparison of the turn rates of all heroes.
 * : Despite not requiring to turn in order to take any action, Io still uses a turn rate (0.7). This means, despite starting to move/attack/cast spells instantly at a target behind it, Io still requires roughly 0.13 seconds to turn 180° and face towards the target. This still existing turn rate affects spells which work with the facing angle of the targeted unit, like, and . In order to distinguish where Io is facing its front is marked visually by an arc.
 * During, , and , the caster does not require to turn to take actions either.
 * ,, , , , and  do not require their casters to face towards their target.