diff --git a/decor/elapsed.go b/decor/elapsed.go
index b2e7585..b4ca601 100644
--- a/decor/elapsed.go
+++ b/decor/elapsed.go
@@ -1,16 +1,26 @@
 package decor
 
 import (
-	"fmt"
 	"time"
 )
 
-// Elapsed returns elapsed time decorator.
+// Elapsed decorator. It's wrapper of NewElapsed.
 //
 //	`style` one of [ET_STYLE_GO|ET_STYLE_HHMMSS|ET_STYLE_HHMM|ET_STYLE_MMSS]
 //
 //	`wcc` optional WC config
 func Elapsed(style TimeStyle, wcc ...WC) Decorator {
+	return NewElapsed(style, time.Now(), wcc...)
+}
+
+// NewElapsed returns elapsed time decorator.
+//
+//	`style` one of [ET_STYLE_GO|ET_STYLE_HHMMSS|ET_STYLE_HHMM|ET_STYLE_MMSS]
+//
+//	`startTime` start time
+//
+//	`wcc` optional WC config
+func NewElapsed(style TimeStyle, startTime time.Time, wcc ...WC) Decorator {
 	var wc WC
 	for _, widthConf := range wcc {
 		wc = widthConf
@@ -18,16 +28,16 @@
 	wc.Init()
 	d := &elapsedDecorator{
 		WC:        wc,
-		style:     style,
-		startTime: time.Now(),
+		startTime: startTime,
+		producer:  chooseTimeProducer(style),
 	}
 	return d
 }
 
 type elapsedDecorator struct {
 	WC
-	style       TimeStyle
 	startTime   time.Time
+	producer    func(time.Duration) string
 	msg         string
 	completeMsg *string
 }
@@ -40,26 +50,7 @@
 		return d.FormatMsg(d.msg)
 	}
 
-	timeElapsed := time.Since(d.startTime)
-	hours := int64((timeElapsed / time.Hour) % 60)
-	minutes := int64((timeElapsed / time.Minute) % 60)
-	seconds := int64((timeElapsed / time.Second) % 60)
-
-	switch d.style {
-	case ET_STYLE_GO:
-		d.msg = fmt.Sprint(time.Duration(timeElapsed.Seconds()) * time.Second)
-	case ET_STYLE_HHMMSS:
-		d.msg = fmt.Sprintf("%02d:%02d:%02d", hours, minutes, seconds)
-	case ET_STYLE_HHMM:
-		d.msg = fmt.Sprintf("%02d:%02d", hours, minutes)
-	case ET_STYLE_MMSS:
-		if hours > 0 {
-			d.msg = fmt.Sprintf("%02d:%02d:%02d", hours, minutes, seconds)
-		} else {
-			d.msg = fmt.Sprintf("%02d:%02d", minutes, seconds)
-		}
-	}
-
+	d.msg = d.producer(time.Since(d.startTime))
 	return d.FormatMsg(d.msg)
 }
 
diff --git a/decor/eta.go b/decor/eta.go
index 00ef8c9..dbe4b93 100644
--- a/decor/eta.go
+++ b/decor/eta.go
@@ -55,7 +55,7 @@
 		WC:         wc,
 		average:    average,
 		normalizer: normalizer,
-		producer:   chooseEtaProducer(style),
+		producer:   chooseTimeProducer(style),
 	}
 	return d
 }
@@ -97,7 +97,7 @@
 	d.completeMsg = &msg
 }
 
-// AverageETA decorator.
+// AverageETA decorator. It's wrapper of NewAverageETA.
 //
 //	`style` one of [ET_STYLE_GO|ET_STYLE_HHMMSS|ET_STYLE_HHMM|ET_STYLE_MMSS]
 //
@@ -122,7 +122,7 @@
 	d := &averageETA{
 		WC:        wc,
 		startTime: startTime,
-		producer:  chooseEtaProducer(style),
+		producer:  chooseTimeProducer(style),
 	}
 	return d
 }
@@ -192,7 +192,7 @@
 	})
 }
 
-func chooseEtaProducer(style TimeStyle) func(time.Duration) string {
+func chooseTimeProducer(style TimeStyle) func(time.Duration) string {
 	switch style {
 	case ET_STYLE_HHMMSS:
 		return func(remaining time.Duration) string {