double getFloat32(int byteOffset, [Endianness endian = Endianness.BIG_ENDIAN])

Returns the floating point number represented by the four bytes at the specified byteOffset in this object, in IEEE 754 single-precision binary floating-point format (binary32).

Throws RangeError if byteOffset is negative, or byteOffset + 4 is greater than the length of this object.

Source 

double getFloat32(int byteOffset,
                  [Endianness endian = Endianness.BIG_ENDIAN]);