diff --git a/mem-report b/mem-report
index e3aa3d6..9840d07 100755
--- a/mem-report
+++ b/mem-report
@@ -59,18 +59,50 @@ system_summary = {
   free_memory: to_mb.call((vm[:free] || 0) + (vm[:speculative] || 0)).round(0),
 }
 
-# --- Per-process memory (via ps) ---
+# --- Per-process memory (physical footprint via top, joined with ps) ---
+#
+# We use physical footprint (top's MEM column) rather than ps RSS. RSS counts
+# every resident page, including shared read-only pages like the dyld shared
+# cache and frameworks — so summing it across many processes that share those
+# pages (e.g. 300+ iOS simulator daemons) overcounts wildly. Footprint charges
+# shared pages once and matches what Activity Monitor reports. top truncates
+# command names though, so we pull full paths from ps and join on PID.
 
-ps_output = run("ps -axo pid=,user=,rss=,comm=")
-processes = ps_output.each_line.filter_map do |line|
-  parts = line.strip.split(/\s+/, 4)
-  next if parts.size < 4
+def parse_mem_mb(str)
+  m = str.match(/\A([\d.]+)([KMGB]?)/)
+  return nil unless m
 
-  pid, user, rss_kb, comm = parts
-  rss_mb = rss_kb.to_f / 1024.0
-  next if rss_mb < 0.1
+  val = m[1].to_f
+  case m[2]
+  when "G" then val * 1024
+  when "M" then val
+  when "K" then val / 1024.0
+  else val / 1024.0 / 1024.0 # bytes
+  end
+end
 
-  { pid: pid.to_i, user:, rss_mb:, command: comm }
+footprints = {}
+run("top -l 1 -stats pid,mem").each_line do |line|
+  parts = line.strip.split(/\s+/)
+  next unless parts.size == 2 && parts[0].match?(/\A\d+\z/)
+
+  mb = parse_mem_mb(parts[1])
+  footprints[parts[0].to_i] = mb if mb
+end
+
+commands = {}
+run("ps -axo pid=,comm=").each_line do |line|
+  pid, comm = line.strip.split(/\s+/, 2)
+  commands[pid.to_i] = comm if pid && comm
+end
+
+processes = footprints.filter_map do |pid, mem_mb|
+  next if mem_mb < 0.1
+
+  command = commands[pid]
+  next unless command
+
+  { pid:, mem_mb:, command: }
 end
 
 # --- Grouped memory ---
@@ -100,14 +132,14 @@ def group_name(command)
   File.basename(command).sub(/\.\w+$/, "")
 end
 
-groups = Hash.new { |h, k| h[k] = { rss_mb: 0.0, count: 0 } }
+groups = Hash.new { |h, k| h[k] = { mem_mb: 0.0, count: 0 } }
 processes.each do |proc|
   name = group_name(proc[:command])
-  groups[name][:rss_mb] += proc[:rss_mb]
+  groups[name][:mem_mb] += proc[:mem_mb]
   groups[name][:count] += 1
 end
 
-top_groups = groups.sort_by { -it[1][:rss_mb] }.first(options[:group_top])
+top_groups = groups.sort_by { -it[1][:mem_mb] }.first(options[:group_top])
 
 # --- Output ---
 
@@ -115,9 +147,9 @@ if options[:json]
   data = {
     system: system_summary.transform_values(&:to_i),
     top_groups: top_groups.map do |name, info|
-      { group: name, rss_mb: info[:rss_mb].round(1), process_count: info[:count] }
+      { group: name, footprint_mb: info[:mem_mb].round(1), process_count: info[:count] }
     end,
-    note: "RSS values and group sums can overcount shared memory (shared libraries, frameworks, mmap regions).",
+    note: "Physical footprint (matches Activity Monitor); shared pages are charged once.",
   }
   puts JSON.pretty_generate(data)
   exit
@@ -139,9 +171,9 @@ puts
 
 puts "#{bold}=== Top #{options[:group_top]} Grouped Programs ==#{reset}"
 puts
-puts "  #{dim}%-28s %10s %8s#{reset}" % ["GROUP", "RSS", "PROCS"]
+puts "  #{dim}%-28s %10s %8s#{reset}" % ["GROUP", "MEM", "PROCS"]
 top_groups.each do |name, info|
-  puts "  %-28s %10s %8d" % [name, human_bytes(info[:rss_mb]), info[:count]]
+  puts "  %-28s %10s %8d" % [name, human_bytes(info[:mem_mb]), info[:count]]
 end
 puts
-puts "#{dim}Note: RSS and group sums can overcount shared memory (shared libs, frameworks, mmap).#{reset}"
+puts "#{dim}Note: physical footprint (matches Activity Monitor); shared pages charged once.#{reset}"