diff --git a/virtcontainers/sandbox.go b/virtcontainers/sandbox.go
index c7ae0f60bc..720444afe3 100644
--- a/virtcontainers/sandbox.go
+++ b/virtcontainers/sandbox.go
@@ -1863,7 +1863,10 @@ func (s *Sandbox) updateResources() error {
 		return fmt.Errorf("sandbox config is nil")
 	}
 
-	sandboxVCPUs := s.calculateSandboxCPUs()
+	sandboxVCPUs, err := s.calculateSandboxCPUs()
+	if err != nil {
+		return err
+	}
 	// Add default vcpus for sandbox
 	sandboxVCPUs += s.hypervisor.hypervisorConfig().NumVCPUs
 
@@ -1923,8 +1926,9 @@ func (s *Sandbox) calculateSandboxMemory() int64 {
 	return memorySandbox
 }
 
-func (s *Sandbox) calculateSandboxCPUs() uint32 {
+func (s *Sandbox) calculateSandboxCPUs() (uint32, error) {
 	mCPU := uint32(0)
+	cpusetCount := int(0)
 
 	for _, c := range s.config.Containers {
 		// Do not hot add again non-running containers resources
@@ -1938,9 +1942,22 @@ func (s *Sandbox) calculateSandboxCPUs() uint32 {
 				mCPU += utils.CalculateMilliCPUs(*cpu.Quota, *cpu.Period)
 			}
 
+			set, err := cpuset.Parse(cpu.Cpus)
+			if err != nil {
+				return 0, nil
+			}
+			cpusetCount += set.Size()
 		}
 	}
-	return utils.CalculateVCpusFromMilliCpus(mCPU)
+
+	// If we aren't being constrained, then we could have two scenarios:
+	//  1. BestEffort QoS: no proper support today in Kata.
+	//  2. We could be constrained only by CPUSets. Check for this:
+	if mCPU == 0 && cpusetCount > 0 {
+		return uint32(cpusetCount), nil
+	}
+
+	return utils.CalculateVCpusFromMilliCpus(mCPU), nil
 }
 
 // GetHypervisorType is used for getting Hypervisor name currently used.
@@ -2273,11 +2290,11 @@ func (s *Sandbox) getSandboxCPUSet() (string, string, error) {
 	memResult := cpuset.NewCPUSet()
 	for _, ctr := range s.config.Containers {
 		if ctr.Resources.CPU != nil {
-			currCpuSet, err := cpuset.Parse(ctr.Resources.CPU.Cpus)
+			currCPUSet, err := cpuset.Parse(ctr.Resources.CPU.Cpus)
 			if err != nil {
 				return "", "", fmt.Errorf("unable to parse CPUset.cpus for container %s: %v", ctr.ID, err)
 			}
-			cpuResult = cpuResult.Union(currCpuSet)
+			cpuResult = cpuResult.Union(currCPUSet)
 
 			currMemSet, err := cpuset.Parse(ctr.Resources.CPU.Mems)
 			if err != nil {
diff --git a/virtcontainers/sandbox_test.go b/virtcontainers/sandbox_test.go
index bfc340ccf7..4e4b506659 100644
--- a/virtcontainers/sandbox_test.go
+++ b/virtcontainers/sandbox_test.go
@@ -106,12 +106,18 @@ func TestCreateMockSandbox(t *testing.T) {
 func TestCalculateSandboxCPUs(t *testing.T) {
 	sandbox := &Sandbox{}
 	sandbox.config = &SandboxConfig{}
+
 	unconstrained := newTestContainerConfigNoop("cont-00001")
-	constrained := newTestContainerConfigNoop("cont-00001")
+	constrained := newTestContainerConfigNoop("cont-00002")
+	unconstrainedCpusets0_1 := newTestContainerConfigNoop("cont-00003")
+	unconstrainedCpusets2 := newTestContainerConfigNoop("cont-00004")
+	constrainedCpusets0_7 := newTestContainerConfigNoop("cont-00005")
 	quota := int64(4000)
 	period := uint64(1000)
 	constrained.Resources.CPU = &specs.LinuxCPU{Period: &period, Quota: &quota}
-
+	unconstrainedCpusets0_1.Resources.CPU = &specs.LinuxCPU{Cpus: "0-1"}
+	unconstrainedCpusets2.Resources.CPU = &specs.LinuxCPU{Cpus: "2"}
+	constrainedCpusets0_7.Resources.CPU = &specs.LinuxCPU{Period: &period, Quota: &quota, Cpus: "0-7"}
 	tests := []struct {
 		name       string
 		containers []ContainerConfig
@@ -123,11 +129,14 @@ func TestCalculateSandboxCPUs(t *testing.T) {
 		{"2-constrained", []ContainerConfig{constrained, constrained}, 8},
 		{"3-mix-constraints", []ContainerConfig{unconstrained, constrained, constrained}, 8},
 		{"3-constrained", []ContainerConfig{constrained, constrained, constrained}, 12},
+		{"unconstrained-1-cpuset", []ContainerConfig{unconstrained, unconstrained, unconstrainedCpusets0_1}, 2},
+		{"unconstrained-2-cpuset", []ContainerConfig{unconstrainedCpusets0_1, unconstrainedCpusets2}, 3},
+		{"constrained-cpuset", []ContainerConfig{constrainedCpusets0_7}, 4},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			sandbox.config.Containers = tt.containers
-			got := sandbox.calculateSandboxCPUs()
+			got, _ := sandbox.calculateSandboxCPUs()
 			assert.Equal(t, got, tt.want)
 		})
 	}