diff --git a/packages/melos/lib/src/command_runner/exec.dart b/packages/melos/lib/src/command_runner/exec.dart
index 29401e6f1..5c09edf56 100644
--- a/packages/melos/lib/src/command_runner/exec.dart
+++ b/packages/melos/lib/src/command_runner/exec.dart
@@ -23,7 +23,11 @@ import 'base.dart';
 class ExecCommand extends MelosCommand {
   ExecCommand(super.config) {
     setupPackageFilterParser();
-    argParser.addOption('concurrency', defaultsTo: '5', abbr: 'c');
+    argParser.addOption(
+      'concurrency',
+      defaultsTo: Platform.numberOfProcessors.toString(),
+      abbr: 'c',
+    );
     argParser.addFlag(
       'fail-fast',
       abbr: 'f',
diff --git a/packages/melos/lib/src/commands/exec.dart b/packages/melos/lib/src/commands/exec.dart
index 66cd45e0e..1b694c5ca 100644
--- a/packages/melos/lib/src/commands/exec.dart
+++ b/packages/melos/lib/src/commands/exec.dart
@@ -5,10 +5,11 @@ mixin _ExecMixin on _Melos {
     List<String> execArgs, {
     GlobalOptions? global,
     PackageFilters? packageFilters,
-    int concurrency = 5,
+    int? concurrency,
     bool failFast = false,
     bool orderDependents = false,
   }) async {
+    concurrency ??= Platform.numberOfProcessors;
     final workspace =
         await createWorkspace(global: global, packageFilters: packageFilters);
     final packages = workspace.filteredPackages.values;