diff --git a/appender.go b/appender.go
index 49ca5fa..a182d2f 100644
--- a/appender.go
+++ b/appender.go
@@ -69,6 +69,7 @@ type Appender struct {
 	docsIndexed           int64
 	tooManyRequests       int64
 	bytesTotal            int64
+	bytesUncompTotal      int64
 	availableBulkRequests int64
 	activeCreated         int64
 	activeDestroyed       int64
@@ -220,6 +221,7 @@ func (a *Appender) Stats() Stats {
 		Indexed:               atomic.LoadInt64(&a.docsIndexed),
 		TooManyRequests:       atomic.LoadInt64(&a.tooManyRequests),
 		BytesTotal:            atomic.LoadInt64(&a.bytesTotal),
+		BytesUncompTotal:      atomic.LoadInt64(&a.bytesUncompTotal),
 		AvailableBulkRequests: atomic.LoadInt64(&a.availableBulkRequests),
 		IndexersActive:        a.scalingInformation().activeIndexers,
 		IndexersCreated:       atomic.LoadInt64(&a.activeCreated),
@@ -318,6 +320,11 @@ func (a *Appender) flush(ctx context.Context, bulkIndexer *BulkIndexer) error {
 	if flushed := bulkIndexer.BytesFlushed(); flushed > 0 {
 		a.addCount(int64(flushed), &a.bytesTotal, a.metrics.bytesTotal)
 	}
+	// Record the BulkIndexer buffer's length as the bytesTotal metric after
+	// the request has been flushed.
+	if flushed := bulkIndexer.BytesUncompressedFlushed(); flushed > 0 {
+		a.addCount(int64(flushed), &a.bytesUncompTotal, a.metrics.bytesUncompTotal)
+	}
 	if err != nil {
 		atomic.AddInt64(&a.docsFailed, int64(n))
 		logger.Error("bulk indexing request failed", zap.Error(err))
@@ -719,6 +726,11 @@ type Stats struct {
 	// which counts bytes at the transport level.
 	BytesTotal int64
 
+	// BytesUncompTotal represents the total number of bytes written to
+	// the request body before compression.
+	// The number of bytes written will be equal to BytesTotal if compression is disabled.
+	BytesUncompTotal int64
+
 	// AvailableBulkRequests represents the number of bulk indexers
 	// available for making bulk index requests.
 	AvailableBulkRequests int64
diff --git a/appender_test.go b/appender_test.go
index 3ee76b2..96bc16e 100644
--- a/appender_test.go
+++ b/appender_test.go
@@ -138,6 +138,7 @@ loop:
 		TooManyRequests:       1,
 		AvailableBulkRequests: 10,
 		BytesTotal:            bytesTotal,
+		BytesUncompTotal:      880,
 	}, stats)
 
 	var rm metricdata.ResourceMetrics
@@ -187,6 +188,8 @@ loop:
 			assertCounter(m, stats.AvailableBulkRequests, indexerAttrs)
 		case "elasticsearch.flushed.bytes":
 			assertCounter(m, stats.BytesTotal, indexerAttrs)
+		case "elasticsearch.flushed.uncompressed.bytes":
+			assertCounter(m, stats.BytesUncompTotal, indexerAttrs)
 		case "elasticsearch.buffer.latency", "elasticsearch.flushed.latency":
 			// expect this metric name but no assertions done
 			// as it's histogram and it's checked elsewhere
@@ -196,7 +199,7 @@ loop:
 	})
 
 	assert.Empty(t, unexpectedMetrics)
-	assert.Equal(t, int64(6), asserted.Load())
+	assert.Equal(t, int64(7), asserted.Load())
 	assert.Equal(t, 4, processedAsserted)
 }
 
@@ -311,6 +314,7 @@ func TestAppenderCompressionLevel(t *testing.T) {
 		TooManyRequests:       0,
 		AvailableBulkRequests: 10,
 		BytesTotal:            bytesTotal,
+		BytesUncompTotal:      88, // get this value programmatically?
 	}, stats)
 }
 
diff --git a/bulk_indexer.go b/bulk_indexer.go
index 4d55bb2..c214d34 100644
--- a/bulk_indexer.go
+++ b/bulk_indexer.go
@@ -49,16 +49,17 @@ import (
 // maximum possible size, based on configuration and throughput.
 
 type BulkIndexer struct {
-	client           *elasticsearch.Client
-	maxDocumentRetry int
-	itemsAdded       int
-	bytesFlushed     int
-	jsonw            fastjson.Writer
-	writer           io.Writer
-	gzipw            *gzip.Writer
-	copyBuf          []byte
-	buf              bytes.Buffer
-	retryCounts      map[int]int
+	client             *elasticsearch.Client
+	maxDocumentRetry   int
+	itemsAdded         int
+	bytesFlushed       int
+	bytesUncompFlushed int
+	jsonw              fastjson.Writer
+	writer             *countWriter
+	gzipw              *gzip.Writer
+	copyBuf            []byte
+	buf                bytes.Buffer
+	retryCounts        map[int]int
 }
 
 type BulkIndexerResponseStat struct {
@@ -137,17 +138,32 @@ func init() {
 	})
 }
 
+type countWriter struct {
+	count int
+	io.Writer
+}
+
+func (cw *countWriter) Write(p []byte) (int, error) {
+	cw.count += len(p)
+	return cw.Writer.Write(p)
+}
+
 func NewBulkIndexer(client *elasticsearch.Client, compressionLevel int, maxDocRetry int) *BulkIndexer {
 	b := &BulkIndexer{
 		client:           client,
 		maxDocumentRetry: maxDocRetry,
 		retryCounts:      make(map[int]int),
 	}
+	var writer io.Writer
 	if compressionLevel != gzip.NoCompression {
 		b.gzipw, _ = gzip.NewWriterLevel(&b.buf, compressionLevel)
-		b.writer = b.gzipw
+		writer = b.gzipw
 	} else {
-		b.writer = &b.buf
+		writer = &b.buf
+	}
+	b.writer = &countWriter{
+		0,
+		writer,
 	}
 	return b
 }
@@ -155,10 +171,12 @@ func NewBulkIndexer(client *elasticsearch.Client, compressionLevel int, maxDocRe
 // BulkIndexer resets b, ready for a new request.
 func (b *BulkIndexer) Reset() {
 	b.bytesFlushed = 0
+	b.writer.count = 0
 }
 
 func (b *BulkIndexer) resetBuf() {
 	b.itemsAdded = 0
+	b.writer.count = 0
 	b.buf.Reset()
 	if b.gzipw != nil {
 		b.gzipw.Reset(&b.buf)
@@ -180,6 +198,11 @@ func (b *BulkIndexer) BytesFlushed() int {
 	return b.bytesFlushed
 }
 
+// BytesUncompFlushed returns the number of uncompressed bytes flushed by the bulk indexer.
+func (b *BulkIndexer) BytesUncompFlushed() int {
+	return b.bytesUncompFlushed
+}
+
 type BulkIndexerItem struct {
 	Index      string
 	DocumentID string
@@ -248,6 +271,7 @@ func (b *BulkIndexer) Flush(ctx context.Context) (BulkIndexerResponseStat, error
 	}
 
 	bytesFlushed := b.buf.Len()
+	bytesUncompFlushed := b.writer.count
 	res, err := req.Do(ctx, b.client)
 	if err != nil {
 		b.resetBuf()
@@ -262,6 +286,7 @@ func (b *BulkIndexer) Flush(ctx context.Context) (BulkIndexerResponseStat, error
 	// Record the number of flushed bytes only when err == nil. The body may
 	// not have been sent otherwise.
 	b.bytesFlushed = bytesFlushed
+	b.bytesUncompFlushed = bytesUncompFlushed
 	var resp BulkIndexerResponseStat
 	if res.IsError() {
 		if res.StatusCode == http.StatusTooManyRequests {
diff --git a/metric.go b/metric.go
index b39216e..89424ae 100644
--- a/metric.go
+++ b/metric.go
@@ -33,6 +33,7 @@ type metrics struct {
 	docsActive            metric.Int64UpDownCounter
 	docsIndexed           metric.Int64Counter
 	bytesTotal            metric.Int64Counter
+	bytesUncompTotal      metric.Int64Counter
 	availableBulkRequests metric.Int64UpDownCounter
 	activeCreated         metric.Int64Counter
 	activeDestroyed       metric.Int64Counter
@@ -109,6 +110,12 @@ func newMetrics(cfg Config) (metrics, error) {
 			unit:        "by",
 			p:           &ms.bytesTotal,
 		},
+		{
+			name:        "elasticsearch.flushed.uncompressed.bytes",
+			description: "The total number of uncompressed bytes written to the request body",
+			unit:        "by",
+			p:           &ms.bytesUncompTotal,
+		},
 		{
 			name:        "elasticsearch.indexer.created",
 			description: "The number of active indexer creations.",