diff --git a/pkg/perfdata/perfdata.go b/pkg/perfdata/perfdata.go
index a6f3536..f551c78 100644
--- a/pkg/perfdata/perfdata.go
+++ b/pkg/perfdata/perfdata.go
@@ -3,7 +3,10 @@
 package perfdata // import nocternity.net/gomonop/pkg/perfdata
 
 import (
+	"strconv"
 	"strings"
+
+	"nocternity.net/gomonop/pkg/status"
 )
 
 // Performance data, including a label, units, a value, warning/critical
@@ -71,6 +74,23 @@ func (d *PerfData) SetMax(max string) {
 	d.bits |= PDatMax
 }
 
+// Check the performance data's value against its configured ranges.
+func (d *PerfData) GetStatus() status.Status {
+	value, err := strconv.ParseFloat(d.value, 64)
+	if err != nil {
+		return status.StatusUnknown
+	}
+
+	if d.bits&PDatCrit != 0 && d.crit.Contains(value) {
+		return status.StatusCritical
+	}
+	if d.bits&PDatWarn != 0 && d.warn.Contains(value) {
+		return status.StatusWarning
+	}
+
+	return status.StatusOK
+}
+
 // Converts performance data to a string which may be read by the monitoring
 // system.
 func (d *PerfData) String() string {
diff --git a/pkg/perfdata/perfdata_test.go b/pkg/perfdata/perfdata_test.go
index c112e3a..ac3f3e9 100644
--- a/pkg/perfdata/perfdata_test.go
+++ b/pkg/perfdata/perfdata_test.go
@@ -6,6 +6,7 @@ import (
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+	"nocternity.net/gomonop/pkg/status"
 )
 
 func TestNewNoValue(t *testing.T) {
@@ -167,6 +168,35 @@ func TestSetMaxTwice(t *testing.T) {
 	assert.True(t, data.bits&PDatMax != 0)
 }
 
+func TestCheck(t *testing.T) {
+	warnRange := RangeMinMax("0", "10").Inside()
+	critRange := RangeMinMax("1", "9").Inside()
+
+	type Test struct {
+		in  string
+		out status.Status
+	}
+
+	tests := []Test{
+		{in: "moo", out: status.StatusUnknown},
+		{in: "-1", out: status.StatusOK},
+		{in: "0", out: status.StatusWarning},
+		{in: "1", out: status.StatusCritical},
+		{in: "9", out: status.StatusCritical},
+		{in: "10", out: status.StatusWarning},
+		{in: "11", out: status.StatusOK},
+	}
+	for _, test := range tests {
+		pdat := PerfData{
+			value: test.in,
+			bits:  PDatCrit | PDatWarn,
+			warn:  *warnRange,
+			crit:  *critRange,
+		}
+		assert.Equal(t, test.out, pdat.GetStatus())
+	}
+}
+
 func TestString(t *testing.T) {
 	type Test struct {
 		PerfData