The conversions follow the usual rules for Standard SI Units:
long nanoSeconds = ...
double microSeconds = nanoSeconds / 1e3;
double milliSeconds = microSeconds / 1e3;
double seconds = milliSeconds / 1e3;
// Shortcuts:
double milliSeconds = nanoSeconds / 1e6;
double sconds = nanoSeconds / 1e9;
For some conversions, you can also have a look at the TimeUnit class: It allows conversions between values in different time units, for example
long microSeconds = NANOSECONDS.toMicros(nanoSeconds);
However, it unfortunately does not allow time spans given in double
precision, but only as long
values.
An aside, also mentioned in the comments: Measuring time spans in the order of 10-15ms usually makes no sense due to the limited resolution of the internal timer.