FMath::Sqrt

function Core Since unknown

#include "GenericPlatform/GenericPlatformMath.h"

Access: public Specifiers: static

Description

Returns the square root of Value. A double overload exists. For performance-critical code where precision is less important, consider FMath::InvSqrt.

Signature

static UE_FORCEINLINE_HINT float Sqrt(float Value)

Parameters

Name	Type	Description	Default
Value	float	The value to compute the square root of. Must be non-negative.	—

Return Type

float

Caveats & Gotchas

• Passing a negative value produces NaN on all platforms. Guard with FMath::Abs or a >= 0 check if the input sign is uncertain.
• Square root is expensive relative to a squared comparison. When checking distances, compare squared values (FVector::DistSquared vs FMath::Square(Threshold)) to avoid calling Sqrt entirely.
• FMath::InvSqrtEst provides a fast approximate reciprocal square root — useful for normalising vectors in non-critical paths, but not precise enough for physics or rendering.

Example

Compute vector magnitude manually and time-based ramp C++

// Manual magnitude (prefer FVector::Size() in practice)
float Magnitude = FMath::Sqrt(V.X*V.X + V.Y*V.Y + V.Z*V.Z);

// Ease-in curve using square root
float Alpha = FMath::Clamp(ElapsedTime / Duration, 0.0f, 1.0f);
float EasedAlpha = FMath::Sqrt(Alpha); // fast start, slow end

Version History

Introduced in: unknown

Version	Status	Notes
5.6	stable	—

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