diff --git a/internal/services/mssql/mssql_database_resource.go b/internal/services/mssql/mssql_database_resource.go
index cd0c6efec8a8..88f8b572485b 100644
--- a/internal/services/mssql/mssql_database_resource.go
+++ b/internal/services/mssql/mssql_database_resource.go
@@ -7,6 +7,7 @@ import (
 	"context"
 	"fmt"
 	"log"
+	"math"
 	"strings"
 	"time"
 
@@ -389,8 +390,13 @@ func resourceMsSqlDatabaseCreate(d *pluginsdk.ResourceData, meta interface{}) er
 	if v, ok := d.GetOk("max_size_gb"); ok {
 		// `max_size_gb` is Computed, so has a value after the first run
 		if createMode != string(databases.CreateModeOnlineSecondary) && createMode != string(databases.CreateModeSecondary) {
-			input.Properties.MaxSizeBytes = pointer.To(int64(v.(int)) * 1073741824)
+			v, err := calculateMaxSizeBytes(v.(float64))
+			if err != nil {
+				return err
+			}
+			input.Properties.MaxSizeBytes = v
 		}
+
 		// `max_size_gb` only has change if it is configured
 		if d.HasChange("max_size_gb") && (createMode == string(databases.CreateModeOnlineSecondary) || createMode == string(databases.CreateModeSecondary)) {
 			return fmt.Errorf("it is not possible to change maximum size nor advised to configure maximum size in secondary create mode for %s", id)
@@ -784,9 +790,12 @@ func resourceMsSqlDatabaseUpdate(d *pluginsdk.ResourceData, meta interface{}) er
 
 	if v, ok := d.GetOk("max_size_gb"); ok {
 		// `max_size_gb` is Computed, so has a value after the first run
-		if createMode != string(databases.CreateModeOnlineSecondary) && createMode != string(databases.CreateModeSecondary) {
-			props.MaxSizeBytes = pointer.To(int64(v.(int)) * 1073741824)
+		v, err := calculateMaxSizeBytes(v.(float64))
+		if err != nil {
+			return err
 		}
+		props.MaxSizeBytes = v
+
 		// `max_size_gb` only has change if it is configured
 		if d.HasChange("max_size_gb") && (createMode == string(databases.CreateModeOnlineSecondary) || createMode == string(databases.CreateModeSecondary)) {
 			return fmt.Errorf("it is not possible to change maximum size nor advised to configure maximum size in secondary create mode for %s", id)
@@ -1181,9 +1190,7 @@ func resourceMsSqlDatabaseRead(d *pluginsdk.ResourceData, meta interface{}) erro
 				d.Set("license_type", d.Get("license_type").(string))
 			}
 
-			if props.MaxSizeBytes != nil {
-				d.Set("max_size_gb", int32((*props.MaxSizeBytes)/int64(1073741824)))
-			}
+			d.Set("max_size_gb", d.Get("max_size_gb").(float64))
 
 			if props.CurrentServiceObjectiveName != nil {
 				skuName = *props.CurrentServiceObjectiveName
@@ -1599,10 +1606,10 @@ func resourceMsSqlDatabaseSchema() map[string]*pluginsdk.Schema {
 		"short_term_retention_policy": helper.ShortTermRetentionPolicySchema(),
 
 		"max_size_gb": {
-			Type:         pluginsdk.TypeInt,
+			Type:         pluginsdk.TypeFloat,
 			Optional:     true,
 			Computed:     true,
-			ValidateFunc: validation.IntBetween(1, 4096),
+			ValidateFunc: validation.FloatBetween(0.1, 4096),
 		},
 
 		"min_capacity": {
@@ -1884,3 +1891,27 @@ func resourceMsSqlDatabaseSchema() map[string]*pluginsdk.Schema {
 
 	return resource
 }
+
+func calculateMaxSizeBytes(v float64) (*int64, error) {
+	maxSizeBytes := int64(0)
+	integer := isPositiveInteger(v)
+	if integer {
+		maxSizeBytes = int64(math.Round(v)) * 1073741824
+	} else {
+		// When `max_size_gb` is below 1GB, the API only accepts 100MB and 500MB. 100MB is 104857600, and 500MB is 524288000.
+		// Since 100MB != 0.1 * 1073741824 and 500MB != 0.5 * 1073741824, directly specify the Bytes when `max_size_gb` is specified `0.1` or `0.5`.
+		if int64(math.Round(v*10)) == 1 {
+			maxSizeBytes = 104857600
+		} else if int64(math.Round(v*10)) == 5 {
+			maxSizeBytes = 524288000
+		} else {
+			return nil, fmt.Errorf("`max_size_gb` allows `0.1`, `0.5` and positive integers greater than or equal to 1")
+		}
+	}
+	return pointer.To(maxSizeBytes), nil
+}
+
+func isPositiveInteger(num float64) bool {
+	// Determine whether `num` is a positive integer and >= 1
+	return num >= 1 && num == math.Floor(num)
+}
diff --git a/internal/services/mssql/mssql_database_resource_test.go b/internal/services/mssql/mssql_database_resource_test.go
index 389292857ddf..0e8faf2b61d6 100644
--- a/internal/services/mssql/mssql_database_resource_test.go
+++ b/internal/services/mssql/mssql_database_resource_test.go
@@ -38,6 +38,35 @@ func TestAccMsSqlDatabase_basic(t *testing.T) {
 	})
 }
 
+func TestAccMsSqlDatabase_maxSizeGB(t *testing.T) {
+	data := acceptance.BuildTestData(t, "azurerm_mssql_database", "test")
+	r := MsSqlDatabaseResource{}
+
+	data.ResourceTest(t, r, []acceptance.TestStep{
+		{
+			Config: r.maxSizeGB(data, 0.1),
+			Check: acceptance.ComposeTestCheckFunc(
+				check.That(data.ResourceName).ExistsInAzure(r),
+			),
+		},
+		data.ImportStep("max_size_gb"),
+		{
+			Config: r.maxSizeGB(data, 0.5),
+			Check: acceptance.ComposeTestCheckFunc(
+				check.That(data.ResourceName).ExistsInAzure(r),
+			),
+		},
+		data.ImportStep("max_size_gb"),
+		{
+			Config: r.maxSizeGB(data, 1),
+			Check: acceptance.ComposeTestCheckFunc(
+				check.That(data.ResourceName).ExistsInAzure(r),
+			),
+		},
+		data.ImportStep("max_size_gb"),
+	})
+}
+
 func TestAccMsSqlDatabase_free(t *testing.T) {
 	data := acceptance.BuildTestData(t, "azurerm_mssql_database", "test")
 	r := MsSqlDatabaseResource{}
@@ -96,7 +125,7 @@ func TestAccMsSqlDatabase_complete(t *testing.T) {
 				check.That(data.ResourceName).Key("tags.ENV").HasValue("Test"),
 			),
 		},
-		data.ImportStep("sample_name"),
+		data.ImportStep("sample_name", "max_size_gb"),
 		{
 			Config: r.update(data),
 			Check: acceptance.ComposeTestCheckFunc(
@@ -108,7 +137,7 @@ func TestAccMsSqlDatabase_complete(t *testing.T) {
 				check.That(data.ResourceName).Key("tags.ENV").HasValue("Staging"),
 			),
 		},
-		data.ImportStep("sample_name"),
+		data.ImportStep("sample_name", "max_size_gb"),
 	})
 }
 
@@ -448,56 +477,56 @@ func TestAccMsSqlDatabase_scaleReplicaSet(t *testing.T) {
 				check.That(data.ResourceName).ExistsInAzure(r),
 			),
 		},
-		data.ImportStep("sample_name", "license_type"),
+		data.ImportStep("sample_name", "license_type", "max_size_gb"),
 		{
 			Config: r.scaleReplicaSet(data, "P2"),
 			Check: acceptance.ComposeTestCheckFunc(
 				check.That(data.ResourceName).ExistsInAzure(r),
 			),
 		},
-		data.ImportStep("sample_name", "license_type"),
+		data.ImportStep("sample_name", "license_type", "max_size_gb"),
 		{
 			Config: r.scaleReplicaSet(data, "GP_Gen5_2"),
 			Check: acceptance.ComposeTestCheckFunc(
 				check.That(data.ResourceName).ExistsInAzure(r),
 			),
 		},
-		data.ImportStep("sample_name", "license_type"),
+		data.ImportStep("sample_name", "license_type", "max_size_gb"),
 		{
 			Config: r.scaleReplicaSet(data, "BC_Gen5_2"),
 			Check: acceptance.ComposeTestCheckFunc(
 				check.That(data.ResourceName).ExistsInAzure(r),
 			),
 		},
-		data.ImportStep("sample_name", "license_type"),
+		data.ImportStep("sample_name", "license_type", "max_size_gb"),
 		{
 			Config: r.scaleReplicaSet(data, "GP_Gen5_2"),
 			Check: acceptance.ComposeTestCheckFunc(
 				check.That(data.ResourceName).ExistsInAzure(r),
 			),
 		},
-		data.ImportStep("sample_name", "license_type"),
+		data.ImportStep("sample_name", "license_type", "max_size_gb"),
 		{
 			Config: r.scaleReplicaSet(data, "S2"),
 			Check: acceptance.ComposeTestCheckFunc(
 				check.That(data.ResourceName).ExistsInAzure(r),
 			),
 		},
-		data.ImportStep("sample_name", "license_type"),
+		data.ImportStep("sample_name", "license_type", "max_size_gb"),
 		{
 			Config: r.scaleReplicaSet(data, "Basic"),
 			Check: acceptance.ComposeTestCheckFunc(
 				check.That(data.ResourceName).ExistsInAzure(r),
 			),
 		},
-		data.ImportStep("sample_name", "license_type"),
+		data.ImportStep("sample_name", "license_type", "max_size_gb"),
 		{
 			Config: r.scaleReplicaSet(data, "S1"),
 			Check: acceptance.ComposeTestCheckFunc(
 				check.That(data.ResourceName).ExistsInAzure(r),
 			),
 		},
-		data.ImportStep("sample_name", "license_type"),
+		data.ImportStep("sample_name", "license_type", "max_size_gb"),
 	})
 }
 
@@ -515,7 +544,7 @@ func TestAccMsSqlDatabase_scaleReplicaSetWithFailovergroup(t *testing.T) {
 				check.That(data.ResourceName).Key("sku_name").HasValue("GP_Gen5_2"),
 			),
 		},
-		data.ImportStep(),
+		data.ImportStep("max_size_gb"),
 		{
 			Config: r.scaleReplicaSetWithFailovergroup(data, "GP_Gen5_8", 25),
 			Check: acceptance.ComposeTestCheckFunc(
@@ -525,7 +554,7 @@ func TestAccMsSqlDatabase_scaleReplicaSetWithFailovergroup(t *testing.T) {
 				check.That(data.ResourceName).Key("sku_name").HasValue("GP_Gen5_8"),
 			),
 		},
-		data.ImportStep(),
+		data.ImportStep("max_size_gb"),
 		{
 			Config: r.scaleReplicaSetWithFailovergroup(data, "GP_Gen5_2", 5),
 			Check: acceptance.ComposeTestCheckFunc(
@@ -535,7 +564,7 @@ func TestAccMsSqlDatabase_scaleReplicaSetWithFailovergroup(t *testing.T) {
 				check.That(data.ResourceName).Key("sku_name").HasValue("GP_Gen5_2"),
 			),
 		},
-		data.ImportStep(),
+		data.ImportStep("max_size_gb"),
 	})
 }
 
@@ -607,7 +636,7 @@ func TestAccMsSqlDatabase_threatDetectionPolicy(t *testing.T) {
 				check.That(data.ResourceName).Key("threat_detection_policy.0.email_account_admins").HasValue("Enabled"),
 			),
 		},
-		data.ImportStep("sample_name", "threat_detection_policy.0.storage_account_access_key"),
+		data.ImportStep("sample_name", "threat_detection_policy.0.storage_account_access_key", "max_size_gb"),
 		{
 			Config: r.threatDetectionPolicy(data, "Disabled"),
 			Check: acceptance.ComposeTestCheckFunc(
@@ -616,7 +645,7 @@ func TestAccMsSqlDatabase_threatDetectionPolicy(t *testing.T) {
 				check.That(data.ResourceName).Key("threat_detection_policy.0.state").HasValue("Disabled"),
 			),
 		},
-		data.ImportStep("sample_name", "threat_detection_policy.0.storage_account_access_key"),
+		data.ImportStep("sample_name", "threat_detection_policy.0.storage_account_access_key", "max_size_gb"),
 	})
 }
 
@@ -634,7 +663,7 @@ func TestAccMsSqlDatabase_threatDetectionPolicyNoStorage(t *testing.T) {
 				check.That(data.ResourceName).Key("threat_detection_policy.0.storage_endpoint").IsEmpty(),
 			),
 		},
-		data.ImportStep("sample_name", "threat_detection_policy.0.storage_account_access_key"),
+		data.ImportStep("sample_name", "threat_detection_policy.0.storage_account_access_key", "max_size_gb"),
 		{
 			Config: r.threatDetectionPolicy(data, "Enabled"),
 			Check: acceptance.ComposeTestCheckFunc(
@@ -2374,3 +2403,16 @@ resource "azurerm_mssql_database" "test" {
 }
 `, r.template(data), data.RandomInteger)
 }
+
+func (r MsSqlDatabaseResource) maxSizeGB(data acceptance.TestData, maxSizeGb float64) string {
+	return fmt.Sprintf(`
+%[1]s
+
+resource "azurerm_mssql_database" "test" {
+  name      = "acctest-db-%[2]d"
+  server_id = azurerm_mssql_server.test.id
+  sku_name       = "Basic"
+  max_size_gb    = %[3]f
+}
+`, r.template(data), data.RandomInteger, maxSizeGb)
+}
diff --git a/website/docs/r/mssql_database.html.markdown b/website/docs/r/mssql_database.html.markdown
index c82575621f28..92c7323d81b8 100644
--- a/website/docs/r/mssql_database.html.markdown
+++ b/website/docs/r/mssql_database.html.markdown
@@ -204,7 +204,7 @@ The following arguments are supported:
 
 * `max_size_gb` - (Optional) The max size of the database in gigabytes.
 
-~> **NOTE:** This value should not be configured when the `create_mode` is `Secondary` or `OnlineSecondary`, as the sizing of the primary is then used as per [Azure documentation](https://docs.microsoft.com/azure/azure-sql/database/single-database-scale#geo-replicated-database).
+~> **NOTE:** This value should not be configured when the `create_mode` is `Secondary` or `OnlineSecondary`, as the sizing of the primary is then used as per [Azure documentation](https://docs.microsoft.com/azure/azure-sql/database/single-database-scale#geo-replicated-database). The value of `max_size_gb` accepts `0.1`, `0.5` and positive integers greater than or equal to 1. `0.1` means `100MB`, and `0.5` means `500MB`.
 
 * `min_capacity` - (Optional) Minimal capacity that database will always have allocated, if not paused. This property is only settable for Serverless databases.