diff --git a/chart.go b/chart.go
index 61b75af..7c3b06e 100644
--- a/chart.go
+++ b/chart.go
@@ -106,10 +106,16 @@ func (c Chart) calculateFinalLabelWidth(r Renderer) int {
 	if !c.FinalValueLabel.Show {
 		return 0
 	}
+
 	var finalLabelText string
 	for _, s := range c.Series {
 		_, lv := s.GetValue(s.Len() - 1)
-		ll := s.GetYFormatter()(lv)
+		var ll string
+		if c.YRange.Formatter != nil {
+			ll = c.YRange.Formatter(lv)
+		} else {
+			ll = s.GetYFormatter()(lv)
+		}
 		if len(finalLabelText) < len(ll) {
 			finalLabelText = ll
 		}
@@ -178,6 +184,9 @@ func (c Chart) initRanges(canvasBox Box) (xrange Range, yrange Range) {
 		xrange.Min = c.XRange.Min
 		xrange.Max = c.XRange.Max
 	}
+	if c.XRange.Formatter != nil {
+		xrange.Formatter = c.XRange.Formatter
+	}
 	xrange.Domain = canvasBox.Width
 
 	if c.YRange.IsZero() {
@@ -187,6 +196,9 @@ func (c Chart) initRanges(canvasBox Box) (xrange Range, yrange Range) {
 		yrange.Min = c.YRange.Min
 		yrange.Max = c.YRange.Max
 	}
+	if c.YRange.Formatter != nil {
+		yrange.Formatter = c.YRange.Formatter
+	}
 	yrange.Domain = canvasBox.Height
 
 	return
@@ -330,7 +342,7 @@ func (c Chart) drawSeries(r Renderer, canvasBox Box, index int, s Series, xrange
 func (c Chart) drawFinalValueLabel(r Renderer, canvasBox Box, index int, s Series, yrange Range) {
 	if c.FinalValueLabel.Show {
 		_, lv := s.GetValue(s.Len() - 1)
-		ll := s.GetYFormatter()(lv)
+		ll := yrange.Format(lv)
 
 		py := canvasBox.Top
 		ly := yrange.Translate(lv) + py
diff --git a/testserver/main.go b/testserver/main.go
index bb2748b..f5a54ab 100644
--- a/testserver/main.go
+++ b/testserver/main.go
@@ -1,9 +1,10 @@
 package main
 
 import (
-	"bytes"
+	"fmt"
 	"log"
 
+	"github.com/blendlabs/go-util"
 	"github.com/wcharczuk/go-chart"
 	"github.com/wcharczuk/go-web"
 )
@@ -13,7 +14,7 @@ func main() {
 	app.SetName("Chart Test Server")
 	app.SetLogger(web.NewStandardOutputLogger())
 	app.GET("/", func(rc *web.RequestContext) web.ControllerResult {
-		rc.Response.Header().Set("Content-Type", "image/svg+xml")
+		rc.Response.Header().Set("Content-Type", "image/png")
 		c := chart.Chart{
 			Title: "A Test Chart",
 			TitleStyle: chart.Style{
@@ -28,6 +29,12 @@ func main() {
 			YRange: chart.Range{
 				Min: 0.0,
 				Max: 7.0,
+				Formatter: func(v interface{}) string {
+					if typed, isTyped := v.(float64); isTyped {
+						return fmt.Sprintf("%.4f", typed)
+					}
+					return util.StringEmpty
+				},
 			},
 			FinalValueLabel: chart.Style{
 				Show: true,
@@ -46,12 +53,11 @@ func main() {
 			},
 		}
 
-		buffer := bytes.NewBuffer([]byte{})
-		err := c.Render(chart.SVG, buffer)
+		err := c.Render(chart.PNG, rc.Response)
 		if err != nil {
 			return rc.API().InternalError(err)
 		}
-		return rc.Raw(buffer.Bytes())
+		return nil
 	})
 	log.Fatal(app.Start())
 }