diff --git a/cache.go b/cache.go
index db88d2f..bf02c74 100644
--- a/cache.go
+++ b/cache.go
@@ -8,6 +8,7 @@ import (
 	"runtime"
 	"sync"
 	"time"
+	"unsafe"
 )
 
 type Item struct {
@@ -1034,6 +1035,57 @@ func (c *cache) LoadFile(fname string) error {
 	return fp.Close()
 }
 
+// Return current size of all values
+// WARNING: this function assumes all values can be converted to a buffer
+//          of bytes to gather their length
+func (c *cache) Size() (size int) {
+	c.mu.RLock()
+	defer c.mu.RUnlock()
+	size = 0
+	now := time.Now().UnixNano()
+	for _, v := range c.items {
+		// "Inlining" of Expired
+		if v.Expiration > 0 && now > v.Expiration {
+			continue
+		}
+		switch value := v.Object.(type) {
+		case bool:
+			size += int(unsafe.Sizeof(value))
+		case int:
+			size += int(unsafe.Sizeof(value))
+		case int8:
+			size += int(unsafe.Sizeof(value))
+		case int16:
+			size += int(unsafe.Sizeof(value))
+		case int32: // rune
+			size += int(unsafe.Sizeof(value))
+		case int64:
+			size += int(unsafe.Sizeof(value))
+		case uint:
+			size += int(unsafe.Sizeof(value))
+		case uint8: // byte
+			size += int(unsafe.Sizeof(value))
+		case uint16:
+			size += int(unsafe.Sizeof(value))
+		case uint32:
+			size += int(unsafe.Sizeof(value))
+		case uint64:
+			size += int(unsafe.Sizeof(value))
+		case uintptr:
+			size += int(unsafe.Sizeof(value))
+		case float32:
+			size += int(unsafe.Sizeof(value))
+		case float64:
+			size += int(unsafe.Sizeof(value))
+		case string:
+			size += int(unsafe.Sizeof(value))
+			size += len(value)
+		}
+	}
+	return
+}
+
+
 // Copies all unexpired items in the cache into a new map and returns it.
 func (c *cache) Items() map[string]Item {
 	c.mu.RLock()
diff --git a/cache_test.go b/cache_test.go
index de3e9d6..c0cd84c 100644
--- a/cache_test.go
+++ b/cache_test.go
@@ -2,12 +2,15 @@ package cache
 
 import (
 	"bytes"
+	"fmt"
 	"io/ioutil"
+	"math/rand"
 	"runtime"
 	"strconv"
 	"sync"
 	"testing"
 	"time"
+	"unsafe"
 )
 
 type TestStruct struct {
@@ -66,6 +69,17 @@ func TestCache(t *testing.T) {
 	} else if c2 := x.(float64); c2+1.2 != 4.7 {
 		t.Error("c2 (which should be 3.5) plus 1.2 does not equal 4.7; value:", c2)
 	}
+
+	// in Go we have to have a variable with a type to be able to get
+	// the size of the type
+	var a_size = 1
+	var b_size = "b"
+	var c_size = 3.5
+	size := tc.Size()
+	expected_size := int(unsafe.Sizeof(a_size)) + int(unsafe.Sizeof(b_size)) + len(b_size) + int(unsafe.Sizeof(c_size))
+	if size != expected_size {
+		t.Error("size (which should be", expected_size, "); value:", size)
+	}
 }
 
 func TestCacheTimes(t *testing.T) {
@@ -1769,3 +1783,59 @@ func TestGetWithExpiration(t *testing.T) {
 		t.Error("expiration for e is in the past")
 	}
 }
+
+// countBytes from the KVStores
+func countBytes(items map[string]Item) int64 {
+	sum := int64(0)
+	for _, v := range items {
+		if buff, ok := v.Object.([]byte); ok {
+			sum += int64(len(buff))
+		}
+	}
+	return sum
+}
+
+func TestSizeSpeedTest(t *testing.T) {
+        if testing.Short() {
+                t.Skip()
+                fmt.Println("warning: Skipping slow TestSizeSpeed() -- do not use `-short` to not skip this speed tests.")
+                return
+        }
+
+	tc := New(DefaultExpiration, 0)
+
+	fmt.Print("Generate large cache ")
+	for i := 0; i < 100000; i++ {
+		if i % 1000 == 999 {
+			fmt.Print(".")
+		}
+		key := ""
+		key_size := rand.Uint32() % 15 + 5
+		for j := uint32(0); j < key_size; j++ {
+			key += string(rune(rand.Uint32() % 26 + 65))
+		}
+		value := ""
+		value_size := rand.Uint32() % 55 + 5
+		for j := uint32(0); j < value_size; j++ {
+			value += string(rune(rand.Uint32() % 26 + 65))
+		}
+		tc.Set(key, value, DefaultExpiration)
+	}
+	fmt.Println()
+
+	fmt.Print("Time 1,000 Size() calls: ")
+	start := time.Now()
+	for i := 0; i < 1000; i++ {
+		tc.Size()
+	}
+	end := time.Now()
+	fmt.Println("Size() x 1,000 took:", end.Sub(start))
+
+	fmt.Print("Time 1,000 countBytes(Items()) calls: ")
+	start = time.Now()
+	for i := 0; i < 1000; i++ {
+		countBytes(tc.Items())
+	}
+	end = time.Now()
+	fmt.Println("Size() x 1,000 took:", end.Sub(start))
+}