diff --git a/bar.go b/bar.go
index 81d2166..45cff64 100644
--- a/bar.go
+++ b/bar.go
@@ -47,7 +47,7 @@
 	baseF             BarFiller
 	filler            BarFiller
 	id                int
-	width             int
+	reqWidth          int
 	total             int64
 	current           int64
 	lastN             int64
@@ -322,7 +322,7 @@
 		}()
 
 		st := newStatistics(tw, s)
-		frame, lines := s.extender(s.draw(st), s.width, st)
+		frame, lines := s.extender(s.draw(st), s.reqWidth, st)
 		b.extendedLines = lines
 
 		b.toShutdown = s.toComplete && !s.completeFlushed
@@ -332,7 +332,7 @@
 	case <-b.done:
 		s := b.cacheState
 		st := newStatistics(tw, s)
-		frame, lines := s.extender(s.draw(st), s.width, st)
+		frame, lines := s.extender(s.draw(st), s.reqWidth, st)
 		b.extendedLines = lines
 		b.frameCh <- frame
 	}
@@ -399,13 +399,13 @@
 
 	s.bufA.WriteByte('\n')
 
-	if !s.trimSpace && stat.TermWidth >= 2 {
+	if !s.trimSpace {
 		defer s.bufB.WriteByte(' ')
 		s.bufB.WriteByte(' ')
 		stat.OccupiedWidth += 2
 	}
 
-	s.filler.Fill(s.bufB, s.width, stat)
+	s.filler.Fill(s.bufB, s.reqWidth, stat)
 
 	return io.MultiReader(s.bufP, s.bufB, s.bufA)
 }
diff --git a/bar_filler_bar.go b/bar_filler_bar.go
index b473966..4b06906 100644
--- a/bar_filler_bar.go
+++ b/bar_filler_bar.go
@@ -85,13 +85,10 @@
 	s.refill = amount
 }
 
-func (s *barFiller) Fill(w io.Writer, width int, stat decor.Statistics) {
-	// auto shrink
-	if stat.OccupiedWidth+width > stat.TermWidth {
-		width = stat.TermWidth - stat.OccupiedWidth
-	}
-	// don't count rLeft and rRight as progress
-	width -= 2
+func (s *barFiller) Fill(w io.Writer, reqWidth int, stat decor.Statistics) {
+	width := internal.CalcWidthForBarFiller(reqWidth, stat.TermWidth-stat.OccupiedWidth)
+
+	width -= 2 // don't count rLeft and rRight as progress
 	if width < 2 {
 		return
 	}
diff --git a/bar_filler_spinner.go b/bar_filler_spinner.go
index e90b09d..845801f 100644
--- a/bar_filler_spinner.go
+++ b/bar_filler_spinner.go
@@ -6,6 +6,7 @@
 	"unicode/utf8"
 
 	"github.com/vbauerster/mpb/v5/decor"
+	"github.com/vbauerster/mpb/v5/internal"
 )
 
 // SpinnerAlignment enum.
@@ -39,11 +40,8 @@
 	return filler
 }
 
-func (s *spinnerFiller) Fill(w io.Writer, width int, stat decor.Statistics) {
-	// auto shrink
-	if stat.OccupiedWidth+width > stat.TermWidth {
-		width = stat.TermWidth - stat.OccupiedWidth
-	}
+func (s *spinnerFiller) Fill(w io.Writer, reqWidth int, stat decor.Statistics) {
+	width := internal.CalcWidthForBarFiller(reqWidth, stat.TermWidth-stat.OccupiedWidth)
 
 	frame := s.frames[s.count%uint(len(s.frames))]
 	frameWidth := utf8.RuneCountInString(frame)
diff --git a/bar_option.go b/bar_option.go
index 02589fc..9a55a8d 100644
--- a/bar_option.go
+++ b/bar_option.go
@@ -46,7 +46,7 @@
 // BarWidth sets bar width independent of the container.
 func BarWidth(width int) BarOption {
 	return func(s *bState) {
-		s.width = width
+		s.reqWidth = width
 	}
 }
 
diff --git a/bar_test.go b/bar_test.go
index 21de834..e6d5dd2 100644
--- a/bar_test.go
+++ b/bar_test.go
@@ -144,8 +144,8 @@
 func TestBarStyle(t *testing.T) {
 	var buf bytes.Buffer
 	customFormat := "╢▌▌░╟"
-	p := New(WithOutput(&buf))
 	total := 80
+	p := New(WithOutput(&buf), WithWidth(total))
 	bar := p.AddBar(int64(total), BarStyle(customFormat), TrimSpace())
 
 	for i := 0; i < total; i++ {
diff --git a/container_option.go b/container_option.go
index 2f96bb4..fac59e4 100644
--- a/container_option.go
+++ b/container_option.go
@@ -21,14 +21,11 @@
 	}
 }
 
-// WithWidth sets container width. Default is 80. Bars inherit this
-// width, as long as no BarWidth is applied.
+// WithWidth sets container width. If not set underlying bars will
+// occupy whole term width.
 func WithWidth(width int) ContainerOption {
 	return func(s *pState) {
-		if width < 0 {
-			return
-		}
-		s.width = width
+		s.reqWidth = width
 	}
 }
 
diff --git a/draw_test.go b/draw_test.go
index de3e2a9..43f0477 100644
--- a/draw_test.go
+++ b/draw_test.go
@@ -3,7 +3,6 @@
 import (
 	"bytes"
 	"testing"
-	"unicode/utf8"
 )
 
 func TestDraw(t *testing.T) {
@@ -23,7 +22,7 @@
 				total:    60,
 				current:  20,
 				barWidth: 80,
-				want:     "",
+				want:     "  ",
 			},
 			{
 				name:      "t,c,bw{60,20,80}trim",
@@ -40,7 +39,7 @@
 				total:    60,
 				current:  20,
 				barWidth: 80,
-				want:     "",
+				want:     "  ",
 			},
 			{
 				name:      "t,c,bw{60,20,80}trim",
@@ -323,7 +322,7 @@
 	for termWidth, cases := range testSuite {
 		for _, tc := range cases {
 			s := newTestState(tc.reverse)
-			s.width = tc.barWidth
+			s.reqWidth = tc.barWidth
 			s.total = tc.total
 			s.current = tc.current
 			s.trimSpace = tc.trimSpace
@@ -337,10 +336,6 @@
 			by := tmpBuf.Bytes()
 			by = by[:len(by)-1]
 
-			if utf8.RuneCount(by) > termWidth {
-				t.Errorf("termWidth:%d %q barWidth:%d overflow termWidth\n", termWidth, tc.name, utf8.RuneCount(by))
-			}
-
 			got := string(by)
 			if got != tc.want {
 				t.Errorf("termWidth:%d %q want: %q %d, got: %q %d\n", termWidth, tc.name, tc.want, len(tc.want), got, len(got))
diff --git a/internal/percentage.go b/internal/percentage.go
index e321e0a..d0ca0db 100644
--- a/internal/percentage.go
+++ b/internal/percentage.go
@@ -16,3 +16,10 @@
 func PercentageRound(total, current int64, width int) float64 {
 	return math.Round(Percentage(total, current, width))
 }
+
+func CalcWidthForBarFiller(reqWidth, available int) int {
+	if reqWidth <= 0 || reqWidth >= available {
+		return available
+	}
+	return reqWidth
+}
diff --git a/progress.go b/progress.go
index 70c6fb4..bd78839 100644
--- a/progress.go
+++ b/progress.go
@@ -19,8 +19,6 @@
 const (
 	// default RefreshRate
 	prr = 120 * time.Millisecond
-	// default width
-	pwidth = 80
 )
 
 // Progress represents the container that renders Progress bars
@@ -46,7 +44,7 @@
 
 	// following are provided/overrided by user
 	idCount          int
-	width            int
+	reqWidth         int
 	popCompleted     bool
 	rr               time.Duration
 	uwg              *sync.WaitGroup
@@ -70,7 +68,6 @@
 func NewWithContext(ctx context.Context, options ...ContainerOption) *Progress {
 	s := &pState{
 		bHeap:      priorityQueue{},
-		width:      pwidth,
 		rr:         prr,
 		parkedBars: make(map[*Bar]*Bar),
 		output:     os.Stdout,
@@ -113,7 +110,7 @@
 // Panics if *Progress instance is done, i.e. called after *Progress.Wait().
 func (p *Progress) Add(total int64, filler BarFiller, options ...BarOption) *Bar {
 	if filler == nil {
-		filler = NewBarFiller(DefaultBarStyle, false)
+		filler = BarFillerFunc(func(io.Writer, int, decor.Statistics) {})
 	}
 	p.bwg.Add(1)
 	result := make(chan *Bar)
@@ -233,7 +230,7 @@
 
 	tw, err := cw.GetWidth()
 	if err != nil {
-		tw = s.width
+		tw = s.reqWidth
 	}
 	for i := 0; i < s.bHeap.Len(); i++ {
 		bar := s.bHeap[i]
@@ -347,7 +344,7 @@
 		filler:   filler,
 		priority: s.idCount,
 		id:       s.idCount,
-		width:    s.width,
+		reqWidth: s.reqWidth,
 		debugOut: s.debugOut,
 		extender: func(r io.Reader, _ int, _ decor.Statistics) (io.Reader, int) {
 			return r, 0
@@ -364,9 +361,9 @@
 		bs.priority = -1
 	}
 
-	bs.bufP = bytes.NewBuffer(make([]byte, 0, bs.width))
-	bs.bufB = bytes.NewBuffer(make([]byte, 0, bs.width))
-	bs.bufA = bytes.NewBuffer(make([]byte, 0, bs.width))
+	bs.bufP = bytes.NewBuffer(make([]byte, 0, 64))
+	bs.bufB = bytes.NewBuffer(make([]byte, 0, 128))
+	bs.bufA = bytes.NewBuffer(make([]byte, 0, 64))
 
 	return bs
 }