diff --git a/pkg/cli/environment.go b/pkg/cli/environment.go
index 31e3c50f5..627a5b6f0 100644
--- a/pkg/cli/environment.go
+++ b/pkg/cli/environment.go
@@ -25,12 +25,14 @@ package cli
 
 import (
 	"fmt"
+	"log/slog"
 	"net/http"
 	"os"
 	"strconv"
 	"strings"
 
 	"github.com/spf13/pflag"
+	"k8s.io/apimachinery/pkg/api/resource"
 	"k8s.io/cli-runtime/pkg/genericclioptions"
 	"k8s.io/client-go/rest"
 
@@ -119,8 +121,8 @@ func New() *EnvSettings {
 		BurstLimit:                envIntOr("HELM_BURST_LIMIT", defaultBurstLimit),
 		QPS:                       envFloat32Or("HELM_QPS", defaultQPS),
 		ColorMode:                 envColorMode(),
-		MaxChartSize:              envInt64Or("HELM_MAX_CHART_SIZE", 100*1024*1024), // 100 MiB
-		MaxChartFileSize:          envInt64Or("HELM_MAX_FILE_SIZE", 5*1024*1024),    // 5 MiB
+		MaxChartSize:              envInt64OrQuantityBytes("HELM_MAX_CHART_SIZE", 100*1024*1024), // 100 MiB
+		MaxChartFileSize:          envInt64OrQuantityBytes("HELM_MAX_FILE_SIZE", 5*1024*1024),    // 5 MiB
 	}
 	env.Debug, _ = strconv.ParseBool(os.Getenv("HELM_DEBUG"))
 
@@ -220,18 +222,36 @@ func envFloat32Or(name string, def float32) float32 {
 	return float32(ret)
 }
 
-// We want to handle int64 like returned by https://pkg.go.dev/io/fs#FileInfo
-func envInt64Or(name string, def int64) int64 {
+// Tries to parse as a k8s Quantity first, falls back to plain int64 parsing.
+func envInt64OrQuantityBytes(name string, def int64) int64 {
 	if name == "" {
 		return def
 	}
-	envVal := envOr(name, strconv.FormatInt(def, 10))
-	ret, err := strconv.ParseInt(envVal, 10, 64)
-	if err != nil {
-		fmt.Fprintf(os.Stderr, "Warning: Environment variable %s has invalid value %q (expected an integer): %v\n", name, envVal, err)
+	envVal := os.Getenv(name)
+	if envVal == "" {
 		return def
 	}
-	return ret
+
+	envVal = strings.TrimSpace(envVal)
+
+	if q, err := resource.ParseQuantity(envVal); err == nil {
+		if v, ok := q.AsInt64(); ok {
+			return v
+		}
+		f := q.AsApproximateFloat64()
+		if f > 0 && f < float64(^uint64(0)>>1) {
+			return int64(f)
+		}
+		slog.Warn("Environment variable %s is too large to fit in int64: %q", name, envVal)
+		return def
+	}
+
+	if v, err := strconv.ParseInt(envVal, 10, 64); err == nil {
+		return v
+	}
+
+	slog.Warn("Environment variable %s has invalid value %q (expected int or k8s Quantity like 512Mi): using default %d", name, envVal, def)
+	return def
 }
 
 func envCSV(name string) (ls []string) {
diff --git a/pkg/cli/environment_test.go b/pkg/cli/environment_test.go
index 76ee15af6..3d8b39b2f 100644
--- a/pkg/cli/environment_test.go
+++ b/pkg/cli/environment_test.go
@@ -242,7 +242,7 @@ func TestEnvOrBool(t *testing.T) {
 	}
 }
 
-func TestEnvInt64Or(t *testing.T) {
+func TestEnvInt64OrQuantityBytes(t *testing.T) {
 	envName := "TEST_ENV_INT64"
 
 	tests := []struct {
@@ -253,9 +253,9 @@ func TestEnvInt64Or(t *testing.T) {
 		expected int64
 	}{
 		{
-			name:     "empty env with default",
+			name:     "empty env name uses default",
 			env:      "",
-			val:      "",
+			val:      "999",
 			def:      100,
 			expected: 100,
 		},
@@ -280,16 +280,78 @@ func TestEnvInt64Or(t *testing.T) {
 			def:      200,
 			expected: 200,
 		},
+
+		// Quantity cases (bytes)
+		{
+			name:     "quantity Mi",
+			env:      envName,
+			val:      "512Mi",
+			def:      100,
+			expected: 512 * 1024 * 1024,
+		},
+		{
+			name:     "quantity Gi",
+			env:      envName,
+			val:      "2Gi",
+			def:      100,
+			expected: 2 * 1024 * 1024 * 1024,
+		},
+		{
+			name:     "quantity Ki",
+			env:      envName,
+			val:      "4096Ki",
+			def:      100,
+			expected: 4096 * 1024,
+		},
+		{
+			name: "decimal SI 1G (base10)",
+			env:  envName,
+			val:  "1G",
+			def:  100,
+			// 1G in decimal SI is 1,000,000,000 bytes
+			expected: 1_000_000_000,
+		},
+		{
+			name:     "decimal SI 500M (base10)",
+			env:      envName,
+			val:      "500M",
+			def:      100,
+			expected: 500_000_000,
+		},
+		{
+			name:     "lowercase suffix returns default with error message",
+			env:      envName,
+			val:      "1gi",
+			def:      100,
+			expected: 100, // Returns default but prints error about uppercase requirement
+		},
+		{
+			name:     "whitespace trimmed",
+			env:      envName,
+			val:      " 256Mi ",
+			def:      100,
+			expected: 256 * 1024 * 1024,
+		},
+		{
+			name: "too large to fit in int64 returns default",
+			env:  envName,
+			// ~9.22e18 is max int64; use larger than that to trigger overflow handling.
+			val:      "10000000000Gi", // 10,000,000,000 * 1024^3 bytes ≈ 1.07e22
+			def:      1234,
+			expected: 1234,
+		},
 	}
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
+			// Clear previous value to avoid bleed between tests
+			t.Setenv(envName, "")
 			if tt.env != "" {
 				t.Setenv(tt.env, tt.val)
 			}
-			actual := envInt64Or(tt.env, tt.def)
+			actual := envInt64OrQuantityBytes(tt.env, tt.def)
 			if actual != tt.expected {
-				t.Errorf("expected result %d, got %d", tt.expected, actual)
+				t.Errorf("expected result %d, got %d (env=%q val=%q def=%d)", tt.expected, actual, tt.env, tt.val, tt.def)
 			}
 		})
 	}