diff --git a/usr.bin/procstat/procstat.1 b/usr.bin/procstat/procstat.1
--- a/usr.bin/procstat/procstat.1
+++ b/usr.bin/procstat/procstat.1
@@ -687,6 +687,8 @@
 starting address of mapping
 .It END
 ending address of mapping
+.It SIZE
+size of mapping
 .It PRT
 protection flags
 .It RES
diff --git a/usr.bin/procstat/procstat_vm.c b/usr.bin/procstat/procstat_vm.c
--- a/usr.bin/procstat/procstat_vm.c
+++ b/usr.bin/procstat/procstat_vm.c
@@ -51,9 +51,10 @@
 
 	ptrwidth = 2*sizeof(void *) + 2;
 	if ((procstat_opts & PS_OPT_NOHEADER) == 0)
-		xo_emit("{T:/%5s %*s %*s %3s %4s %4s %3s %3s %-5s %-2s %-s}\n",
-		    "PID", ptrwidth, "START", ptrwidth, "END", "PRT", "RES",
-		    "PRES", "REF", "SHD", "FLAG", "TP", "PATH");
+		xo_emit(
+		    "{T:/%5s %*s %*s %3s %3s %4s %4s %3s %3s %-5s %-2s %-s}\n",
+		    "PID", ptrwidth, "START", ptrwidth, "END", "SIZE", "PRT",
+		    "RES", "PRES", "REF", "SHD", "FLAG", "TP", "PATH");
 
 	xo_emit("{ek:process_id/%d}", kipp->ki_pid);
 
@@ -69,8 +70,12 @@
 		    (uintmax_t)kve->kve_start);
 		xo_emit("{d:kve_end/%#*jx} ", ptrwidth,
 		    (uintmax_t)kve->kve_end);
+		xo_emit("{h,hn-decimal:kve_size/%ju} ",
+		    (uintmax_t)(kve->kve_end - kve->kve_start));
 		xo_emit("{e:kve_start/%#jx}", (uintmax_t)kve->kve_start);
 		xo_emit("{e:kve_end/%#jx}", (uintmax_t)kve->kve_end);
+		xo_emit("{e:kve_size/%ju} ",
+		    (uintmax_t)(kve->kve_end - kve->kve_start));
 		xo_emit("{d:read/%s}", kve->kve_protection & KVME_PROT_READ ?
 		    "r" : "-");
 		xo_emit("{d:write/%s}", kve->kve_protection & KVME_PROT_WRITE ?