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samtools-depth(1)	      Bioinformatics tools	       samtools-depth(1)

NAME
     samtools depth - computes the read depth at each position or region

SYNOPSIS
     samtools	       depth	     [options]	       [in1.sam|in1.bam|in1.cram
     [in2.sam|in2.bam|in2.cram] [...]]

DESCRIPTION
     Computes the depth at each position or region.

OPTIONS
     -a      Output all positions (including those with zero depth)

     -a -a, -aa
	     Output absolutely all positions,  including  unused  reference  se-
	     quences.  Note that when used in conjunction with a BED file the -a
	     option  may sometimes operate as if -aa was specified if the refer-
	     ence sequence has coverage outside of the region specified  in  the
	     BED file.

     -b FILE
	     Compute  depth  at  list  of  positions or regions in specified BED
	     FILE.  []

     -f FILE
	     Use the BAM files specified in the FILE (a file of  filenames,  one
	     file per line) []

     -H      Write  a  comment line showing column names at the beginning of the
	     output.  The names are CHROM, POS, and then the input file name for
	     each depth column.  If one of the inputs came from stdin, the  name
	     "-" will be used for the corresponding column.

     -l INT  Ignore  reads shorter than INT.  This is the number of bases in the
	     sequence, minus any soft clips.

     -m, -d INT
	     (Deprecated since 1.13) This option previously limited the depth to
	     a maximum value.  It is still accepted as an option, but ignored.

	     Note for single files, the behaviour of old samtools depth  -J  -q0
	     -d  INT FILE is identical to samtools mpileup -A -Q0 -x -d INT FILE
	     | cut -f 1,2,4

     -o FILE
	     Write output to FILE.  Using "-" for FILE will send the  output  to
	     stdout (also the default if this option is not used).

     -q, --min-BQ INT
	     Only count reads with base quality greater than or equal to INT

     -Q, --min-MQ INT
	     Only count reads with mapping quality greater than or equal to INT

     -r CHR:FROM-TO
	     Only report depth in specified region.

     -X      If this option is set, it will allow the user to specify customized
	     index  file location(s) if the data folder does not contain any in-
	     dex   file.   Example   usage:   samtools	 depth	 [options]    -X
	     /data_folder/in1.bam [/data_folder/in2.bam [...]] /index_folder/in-
	     dex1.bai [/index_folder/index2.bai [...]]

     -g FLAGS
	     By  default, reads that have any of the flags UNMAP, SECONDARY, QC-
	     FAIL, or DUP set are skipped. To include these reads  back  in  the
	     analysis,	use  this  option together with the desired flag or flag
	     combination.  FLAGS can be specified in hex by beginning with  `0x'
	     (i.e.  /^0x[0-9A-F]+/),  in  octal  by  beginning	with  `0'  (i.e.
	     /^0[0-7]+/), as a decimal number not beginning with  '0'  or  as  a
	     comma-separated list of flag names. [0]

	     For a list of flag names see samtools-flags(1).

     -G FLAGS, --excl-flags FLAGS
	     Discard  reads  that  have any of the flags specified by FLAGS set.
	     FLAGS are specified as  for  the  -g  option.  [UNMAP,SECONDARY,QC-
	     FAIL,DUP]

     --incl-flags FLAGS
	     Only  include  reads  with at least one bit set in FLAGS present in
	     the FLAG field.  FLAGS are specified as for the -g option. [0]

     --require-flags FLAGS
	     Only include reads with all bits set in FLAGS present in  the  FLAG
	     field.  FLAGS are specified as for the -g option. [0]

     -J      Include reads with deletions in depth computation.

     -s      For the overlapping section of a read pair, count only the bases of
	     the first read.  Note this algorithm changed in 1.13 so the results
	     may differ slightly to older releases.

CAVEATS
     It  may appear that "samtools depth" is simply "samtools mpileup" with some
     of the columns removed, and indeed earlier versions of  this  command  were
     just this.  However both then and now there are subtle differences in para-
     meters which make the two not entirely comparable.  Differences, other than
     the obvious speed benefits, include:

     o Deletions  (CIGAR  element "D") are ignored by default in "depth".  These
       may be counted by adding the -J	option.   "Mpileup"  always  counts  the
       deleted bases, and has no option to toggle this.

     o Beware there are idiosyncrasies in option naming.  Specifically -q and -Q
       options have their meanings swapped between "depth" and "mpileup".

     o The  removal  of  overlapping  sequences  (option -s) is on by default in
       "mpileup" and off by default in "depth".  Additionally  the  overlap  re-
       moval algorithm differs, giving subtle changes when Ns are present in the
       sequence.   Also  any  paired  read  is considered for overlap removal by
       "depth", rather	than  only  those  with  the  properly-paired  flag  set
       ("mpileup").  See above for a more detailed description.

     o The default minimum quality value is 0 for "depth" and 13 for "mpileup".

     o Specifying  multiple  BAMs  will  produce  one depth column per file with
       "depth", but these are merged in "mpileup".

     o "Depth" doesn't have a maximum depth limit, while "mpileup" defaults to a
       maximum of 8000.

     o If a reference is specified to "mpileup" the BAQ algorithm will	be  used
       to  adjust  quality  values,  although it can be disabled.  "Depth" never
       uses BAQ.

AUTHOR
     Written by Heng Li and James Bonfield from the Sanger Institute.

SEE ALSO
     samtools(1), samtools-mpileup(1), samtools-coverage(1), samtools-sort(1)

     Samtools website: <http://www.htslib.org/>

samtools-1.23.1 		  18 March 2026 	       samtools-depth(1)

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