diff --git a/range.go b/range.go
index 57dbd20..ec9265d 100644
--- a/range.go
+++ b/range.go
@@ -38,7 +38,10 @@ func NewRange(min, max float64, divideCount int) Range {
 	r := math.Abs(max - min)
 
 	// 最小单位计算
-	unit := 5
+	unit := 2
+	if r > 10 {
+		unit = 5
+	}
 	if r > 100 {
 		unit = 20
 	}
@@ -65,8 +68,7 @@ func (r *Range) getHeight(value float64) int {
 }
 
 func (r *Range) getRestHeight(value float64) int {
-	v := 1 - (value-r.Min)/(r.Max-r.Min)
-	return int(v * float64(r.Size))
+	return r.Size - r.getHeight(value)
 }
 
 func (r *Range) GetRange(index int) (float64, float64) {
diff --git a/range_test.go b/range_test.go
index 151a0bb..b10002f 100644
--- a/range_test.go
+++ b/range_test.go
@@ -33,7 +33,7 @@ func TestRange(t *testing.T) {
 
 	r := NewRange(0, 8, 6)
 	assert.Equal(0.0, r.Min)
-	assert.Equal(30.0, r.Max)
+	assert.Equal(12.0, r.Max)
 
 	r = NewRange(0, 12, 6)
 	assert.Equal(0.0, r.Min)
@@ -47,3 +47,30 @@ func TestRange(t *testing.T) {
 	assert.Equal(0.0, r.Min)
 	assert.Equal(480.0, r.Max)
 }
+
+func TestRangeHeightWidth(t *testing.T) {
+	assert := assert.New(t)
+	r := NewRange(0, 8, 6)
+	r.Size = 100
+
+	assert.Equal(33, r.getHeight(4))
+	assert.Equal(67, r.getRestHeight(4))
+
+	assert.Equal(33, r.getWidth(4))
+	r.Boundary = true
+	assert.Equal(41, r.getWidth(4))
+}
+
+func TestRangeGetRange(t *testing.T) {
+	assert := assert.New(t)
+	r := NewRange(0, 8, 6)
+	r.Size = 120
+
+	f1, f2 := r.GetRange(0)
+	assert.Equal(0.0, f1)
+	assert.Equal(20.0, f2)
+
+	f1, f2 = r.GetRange(2)
+	assert.Equal(40.0, f1)
+	assert.Equal(60.0, f2)
+}