diff --git a/plan.go b/plan.go
index 557d4d17ac..391a3ac6ff 100644
--- a/plan.go
+++ b/plan.go
@@ -127,14 +127,14 @@ type PlanTier struct {
 
 // PlanTransformUsage represents the bucket billing configuration.
 type PlanTransformUsage struct {
-	BucketSize int64                   `json:"bucket_size"`
-	Round      PlanTransformUsageRound `json:"round"`
+	DivideBy int64                   `json:"divide_by"`
+	Round    PlanTransformUsageRound `json:"round"`
 }
 
 // PlanTransformUsageParams represents the bucket billing configuration.
 type PlanTransformUsageParams struct {
-	BucketSize *int64  `form:"bucket_size"`
-	Round      *string `form:"round"`
+	DivideBy *int64  `form:"divide_by"`
+	Round    *string `form:"round"`
 }
 
 // PlanTierParams configures tiered pricing
diff --git a/plan_test.go b/plan_test.go
index 5851b2b424..f1304ca7b8 100644
--- a/plan_test.go
+++ b/plan_test.go
@@ -66,8 +66,8 @@ func TestPlanParams_AppendTo(t *testing.T) {
 		{"tiers[0][up_to]", &PlanParams{Tiers: tiers}, strconv.FormatUint(321, 10)},
 		{"tiers[1][amount]", &PlanParams{Tiers: tiers}, strconv.FormatUint(123, 10)},
 		{"tiers[1][up_to]", &PlanParams{Tiers: tiers}, "inf"},
-		{"transform_usage[bucket_size]", &PlanParams{TransformUsage: &PlanTransformUsageParams{BucketSize: Int64(123), Round: String("round_up")}}, strconv.FormatUint(123, 10)},
-		{"transform_usage[round]", &PlanParams{TransformUsage: &PlanTransformUsageParams{BucketSize: Int64(123), Round: String("round_up")}}, "round_up"},
+		{"transform_usage[divide_by]", &PlanParams{TransformUsage: &PlanTransformUsageParams{DivideBy: Int64(123), Round: String("round_up")}}, strconv.FormatUint(123, 10)},
+		{"transform_usage[round]", &PlanParams{TransformUsage: &PlanTransformUsageParams{DivideBy: Int64(123), Round: String("round_up")}}, "round_up"},
 		{"trial_period_days", &PlanParams{TrialPeriodDays: Int64(123)}, strconv.FormatUint(123, 10)},
 		{"usage_type", &PlanParams{UsageType: String("metered")}, "metered"},
 	}