diff --git a/CHANGELOG.md b/CHANGELOG.md
index 69b164a7a..af3eab441 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -18,6 +18,7 @@
 - relay: add option relay.network.websocket_permessage_deflate ([#1549](https://github.com/weechat/weechat/issues/1549))
 - relay: add option relay.look.raw_messages_max_length ([#2122](https://github.com/weechat/weechat/issues/2122))
 - relay: add infos "relay_api_version" and "relay_api_version_number"
+- core: add hdata count in evaluation of expressions with `hdata_count:name[list]` or `hdata_count:name[pointer]`
 - core: add completion "bars_items"
 - api: add hashtable type "longlong"
 
diff --git a/doc/en/weechat_plugin_api.en.adoc b/doc/en/weechat_plugin_api.en.adoc
index ab168ca69..353ea326c 100644
--- a/doc/en/weechat_plugin_api.en.adoc
+++ b/doc/en/weechat_plugin_api.en.adoc
@@ -2616,8 +2616,7 @@ str3 = weechat.string_input_for_buffer("//test")  # "/test"
 
 ==== string_eval_expression
 
-_WeeChat ≥ 0.4.0, updated in 0.4.2, 0.4.3, 1.0, 1.1, 1.2, 1.3, 1.6, 1.8, 2.0,
-2.2, 2.3, 2.7, 2.9, 3.1, 3.2, 3.3, 3.4, 3.6, 3.8, 4.0.0, 4.2.0, 4.3.0._
+_WeeChat ≥ 0.4.0, updated in 0.4.2, 0.4.3, 1.0, 1.1, 1.2, 1.3, 1.6, 1.8, 2.0, 2.2, 2.3, 2.7, 2.9, 3.1, 3.2, 3.3, 3.4, 3.6, 3.8, 4.0.0, 4.2.0, 4.3.0, 4.4.0._
 
 Evaluate an expression and return result as a string.
 Special variables with format `+${variable}+` are expanded (see table below).
@@ -3332,6 +3331,12 @@ expanded to last):
 | >> `+${define:len,${calc:5+3}}${len}x${len}+` +
   == `+8x8+`
 
+| `+${hdata_count:name[list]}+` +
+  `+${hdata_count:name[pointer]}+` | 4.4.0
+| Number of items in a hdata list or starting at `pointer`.
+| >> `+${hdata_count:buffer[gui_buffers]}+` +
+  == `+15+`
+
 | `+${sec.data.name}+` |
 | Value of the secured data `name`.
 | >> `+${sec.data.libera_pass}+` +
diff --git a/doc/fr/weechat_plugin_api.fr.adoc b/doc/fr/weechat_plugin_api.fr.adoc
index f0ede7656..3d401eca7 100644
--- a/doc/fr/weechat_plugin_api.fr.adoc
+++ b/doc/fr/weechat_plugin_api.fr.adoc
@@ -2663,8 +2663,7 @@ str3 = weechat.string_input_for_buffer("//test")  # "/test"
 
 ==== string_eval_expression
 
-_WeeChat ≥ 0.4.0, mis à jour dans la 0.4.2, 0.4.3, 1.0, 1.1, 1.2, 1.3, 1.6, 1.8,
-2.0, 2.2, 2.3, 2.7, 2.9, 3.1, 3.2, 3.3, 3.4, 3.6, 3.8, 4.0.0, 4.2.0, 4.3.0._
+_WeeChat ≥ 0.4.0, mis à jour dans la 0.4.2, 0.4.3, 1.0, 1.1, 1.2, 1.3, 1.6, 1.8, 2.0, 2.2, 2.3, 2.7, 2.9, 3.1, 3.2, 3.3, 3.4, 3.6, 3.8, 4.0.0, 4.2.0, 4.3.0, 4.4.0._
 
 Évaluer l'expression et retourner le résultat sous forme de chaîne.
 Les variables spéciales avec le format `+${variable}+` sont étendues (voir le
@@ -3390,6 +3389,12 @@ première étendue à la dernière) :
 | >> `+${define:len,${calc:5+3}}${len}x${len}+` +
   == `+8x8+`
 
+| `+${hdata_count:name[list]}+` +
+  `+${hdata_count:name[pointer]}+` | 4.4.0
+| Nombre d'éléments dans la liste hdata ou en démarrant à `pointer`.
+| >> `+${hdata_count:buffer[gui_buffers]}+` +
+  == `+15+`
+
 | `+${sec.data.nom}+` |
 | Valeur de la donnée sécurisée `nom`.
 | >> `+${sec.data.libera_pass}+` +
diff --git a/doc/it/weechat_plugin_api.it.adoc b/doc/it/weechat_plugin_api.it.adoc
index 5a064fceb..3e713489c 100644
--- a/doc/it/weechat_plugin_api.it.adoc
+++ b/doc/it/weechat_plugin_api.it.adoc
@@ -2772,8 +2772,7 @@ str3 = weechat.string_input_for_buffer("//test")  # "/test"
 // TRANSLATION MISSING
 ==== string_eval_expression
 
-_WeeChat ≥ 0.4.0, updated in 0.4.2, 0.4.3, 1.0, 1.1, 1.2, 1.3, 1.6, 1.8, 2.0,
-2.2, 2.3, 2.7, 2.9, 3.1, 3.2, 3.3, 3.4, 3.6, 3.8, 4.0.0, 4.2.0, 4.3.0._
+_WeeChat ≥ 0.4.0, updated in 0.4.2, 0.4.3, 1.0, 1.1, 1.2, 1.3, 1.6, 1.8, 2.0, 2.2, 2.3, 2.7, 2.9, 3.1, 3.2, 3.3, 3.4, 3.6, 3.8, 4.0.0, 4.2.0, 4.3.0, 4.4.0._
 
 Evaluate an expression and return result as a string.
 Special variables with format `+${variable}+` are expanded (see table below).
@@ -3487,6 +3486,12 @@ expanded to last):
 | >> `+${define:len,${calc:5+3}}${len}x${len}+` +
   == `+8x8+`
 
+| `+${hdata_count:name[list]}+` +
+  `+${hdata_count:name[pointer]}+` | 4.4.0
+| Number of items in a hdata list or starting at `pointer`.
+| >> `+${hdata_count:buffer[gui_buffers]}+` +
+  == `+15+`
+
 | `+${sec.data.name}+` |
 | Value of the secured data `name`.
 | >> `+${sec.data.libera_pass}+` +
diff --git a/doc/ja/weechat_plugin_api.ja.adoc b/doc/ja/weechat_plugin_api.ja.adoc
index 7337c8d6a..779689848 100644
--- a/doc/ja/weechat_plugin_api.ja.adoc
+++ b/doc/ja/weechat_plugin_api.ja.adoc
@@ -2696,8 +2696,7 @@ str3 = weechat.string_input_for_buffer("//test")  # "/test"
 ==== string_eval_expression
 
 // TRANSLATION MISSING
-_WeeChat ≥ 0.4.0, updated in 0.4.2, 0.4.3, 1.0, 1.1, 1.2, 1.3, 1.6, 1.8, 2.0,
-2.2, 2.3, 2.7, 2.9, 3.1, 3.2, 3.3, 3.4, 3.6, 3.8, 4.0.0, 4.2.0, 4.3.0._
+_WeeChat ≥ 0.4.0, updated in 0.4.2, 0.4.3, 1.0, 1.1, 1.2, 1.3, 1.6, 1.8, 2.0, 2.2, 2.3, 2.7, 2.9, 3.1, 3.2, 3.3, 3.4, 3.6, 3.8, 4.0.0, 4.2.0, 4.3.0, 4.4.0._
 
 式を評価して文字列として返す。`+${variable}+`
 という書式で書かれた特殊変数は展開されます (以下の表を参照)。
@@ -3445,6 +3444,13 @@ str5 = weechat.string_eval_expression("password=abc password=def", {}, {}, optio
 | >> `+${define:len,${calc:5+3}}${len}x${len}+` +
   == `+8x8+`
 
+// TRANSLATION MISSING
+| `+${hdata_count:name[list]}+` +
+  `+${hdata_count:name[pointer]}+` | 4.4.0
+| Number of items in a hdata list or starting at `pointer`.
+| >> `+${hdata_count:buffer[gui_buffers]}+` +
+  == `+15+`
+
 | `+${sec.data.name}+` |
 | セキュアデータ `name` の値
 | >> `+${sec.data.libera_pass}+` +
diff --git a/doc/sr/weechat_plugin_api.sr.adoc b/doc/sr/weechat_plugin_api.sr.adoc
index 6cbb5fb3c..bc0ac8f93 100644
--- a/doc/sr/weechat_plugin_api.sr.adoc
+++ b/doc/sr/weechat_plugin_api.sr.adoc
@@ -2529,7 +2529,7 @@ str3 = weechat.string_input_for_buffer("//test")  # "/test"
 
 ==== string_eval_expression
 
-_WeeChat ≥ 0.4.0, ажурирано у верзијама 0.4.2, 0.4.3, 1.0, 1.1, 1.2, 1.3, 1.6, 1.8, 2.0, 2.2, 2.3, 2.7, 2.9, 3.1, 3.2, 3.3, 3.4, 3.6 и 3.8, 4.0.0, 4.2.0, 4.3.0._
+_WeeChat ≥ 0.4.0, ажурирано у верзијама 0.4.2, 0.4.3, 1.0, 1.1, 1.2, 1.3, 1.6, 1.8, 2.0, 2.2, 2.3, 2.7, 2.9, 3.1, 3.2, 3.3, 3.4, 3.6 и 3.8, 4.0.0, 4.2.0, 4.3.0, 4.4.0._
 
 Израчунава израз и враћа вредност као стринг. Специјалне променљиве у формату `+${променљива}+` се развијају (погледајте табелу испод).
 
@@ -3221,6 +3221,13 @@ str5 = weechat.string_eval_expression("password=abc password=def", {}, {}, optio
 | >> `+${define:len,${calc:5+3}}${len}x${len}+` +
   == `+8x8+`
 
+// TRANSLATION MISSING
+| `+${hdata_count:name[list]}+` +
+  `+${hdata_count:name[pointer]}+` | 4.4.0
+| Number of items in a hdata list or starting at `pointer`.
+| >> `+${hdata_count:buffer[gui_buffers]}+` +
+  == `+15+`
+
 | `+${sec.data.име}+` |
 | Вредност обезбеђених података `име`.
 | >> `+${sec.data.libera_pass}+` +
diff --git a/src/core/core-completion.c b/src/core/core-completion.c
index 3c2b7a2d8..af9b8c79e 100644
--- a/src/core/core-completion.c
+++ b/src/core/core-completion.c
@@ -2161,6 +2161,8 @@ completion_list_add_eval_variables_cb (const void *pointer, void *data,
         "${hdata[list].var1.var2}",
         "${hdata[ptr].var1.var2}",
         "${hdata[ptr_name].var1.var2}",
+        "${hdata_count:name[list]}",
+        "${hdata_count:name[ptr]}",
         "${hide:char,string}",
         "${hl:string}",
         "${if:condition?value_if_true:value_if_false}",
diff --git a/src/core/core-eval.c b/src/core/core-eval.c
index 01b215739..c653ab283 100644
--- a/src/core/core-eval.c
+++ b/src/core/core-eval.c
@@ -1134,6 +1134,87 @@ eval_string_define (const char *text, struct t_eval_context *eval_context)
     free (name);
 }
 
+/*
+ * Returns count of items in a hdata, as a string.
+ *
+ * Note: result must be freed after use.
+ */
+
+char *
+eval_hdata_count (const char *text, struct t_eval_context *eval_context)
+{
+    struct t_hdata *hdata;
+    void *pointer;
+    char *pos1, *pos2, *value, *hdata_name, *pointer_name, str_count[64];
+    int rc, count;
+
+    value = NULL;
+    hdata_name = NULL;
+    pointer_name = NULL;
+    pointer = NULL;
+
+    pos1 = strchr (text, '[');
+    if (!pos1)
+        goto end;
+    pos2 = strchr (pos1 + 1, ']');
+    if (!pos2 || (pos2 == pos1 + 1))
+        goto end;
+
+    hdata_name = string_strndup (text, pos1 - text);
+    if (!hdata_name)
+        goto end;
+
+    hdata = hook_hdata_get (NULL, hdata_name);
+    if (!hdata)
+        goto end;
+
+    pointer_name = string_strndup (pos1 + 1, pos2 - pos1 - 1);
+    if (!pointer_name)
+        goto end;
+
+    if (strncmp (pointer_name, "0x", 2) == 0)
+    {
+        rc = sscanf (pointer_name, "%p", &pointer);
+        if ((rc != EOF) && (rc != 0))
+        {
+            if (!hdata_check_pointer (hdata, NULL, pointer))
+                goto end;
+        }
+        else
+            goto end;
+    }
+    else
+    {
+        pointer = hdata_get_list (hdata, pointer_name);
+        if (!pointer)
+        {
+            pointer = hashtable_get (eval_context->pointers, pointer_name);
+            if (!pointer)
+                goto end;
+            if (!hdata_check_pointer (hdata, NULL, pointer))
+                goto end;
+        }
+    }
+
+    if (!pointer)
+    {
+        pointer = hashtable_get (eval_context->pointers, hdata_name);
+        if (!pointer)
+            goto end;
+        if (!hdata_check_pointer (hdata, NULL, pointer))
+            goto end;
+    }
+
+    count = hdata_count (hdata, pointer);
+    snprintf (str_count, sizeof (str_count), "%d", count);
+    value = strdup (str_count);
+
+end:
+    free (hdata_name);
+    free (pointer_name);
+    return (value) ? value : strdup ("0");
+}
+
 /*
  * Gets value of hdata using "path" to a variable.
  *
@@ -1588,6 +1669,8 @@ eval_syntax_highlight (const char *text, struct t_eval_context *eval_context)
  *   - ${random:min,max}: a random integer number between "min" and "max" (inclusive)
  *   - ${translate:string}: the translated string
  *   - ${define:name,value}: declaration of a user variable (return an empty string)
+ *   - ${hdata_count:name[list]}: number of items in this hdata with list
+ *   - ${hdata_count:name[ptr]}: number of items in this hdata with pointer
  *   - ${sec.data.xxx}: the value of the secured data "xxx"
  *   - ${file.section.option}: the value of the config option
  *   - ${name}: the local variable in buffer
@@ -1930,6 +2013,13 @@ eval_replace_vars_cb (void *data,
         goto end;
     }
 
+    /* hdata count */
+    if (strncmp (text, "hdata_count:", 12) == 0)
+    {
+        value = eval_hdata_count (text + 12, eval_context);
+        goto end;
+    }
+
     /* option: if found, return this value */
     if (strncmp (text, "sec.data.", 9) == 0)
     {
diff --git a/tests/unit/core/test-core-eval.cpp b/tests/unit/core/test-core-eval.cpp
index 1b9616d1e..2a2ad1f8d 100644
--- a/tests/unit/core/test-core-eval.cpp
+++ b/tests/unit/core/test-core-eval.cpp
@@ -454,6 +454,7 @@ TEST(CoreEval, EvalExpression)
 {
     struct t_hashtable *pointers, *extra_vars, *options;
     struct t_config_option *ptr_option;
+    struct t_gui_buffer *test_buffer;
     char *value, str_value[256], str_expr[256], *error;
     const char *ptr_debug_output;
     long number;
@@ -996,6 +997,28 @@ TEST(CoreEval, EvalExpression)
     WEE_CHECK_EVAL("core", "${plugin}");
     WEE_CHECK_EVAL("weechat", "${name}");
 
+    /* test hdata count */
+    WEE_CHECK_EVAL("0", "${hdata_count:}");
+    WEE_CHECK_EVAL("0", "${hdata_count:xxx}");
+    WEE_CHECK_EVAL("0", "${hdata_count:buffer[xxx]}");
+    WEE_CHECK_EVAL("0", "${hdata_count:buffer[0x0]}");
+    WEE_CHECK_EVAL("1", "${hdata_count:buffer[gui_buffers]}");
+    snprintf (str_expr, sizeof (str_expr),
+              "${hdata_count:buffer[%p]}", gui_buffers);
+    WEE_CHECK_EVAL("1", str_expr);
+    test_buffer = gui_buffer_new (NULL, "test",
+                                  NULL, NULL, NULL,
+                                  NULL, NULL, NULL);
+    CHECK(test_buffer);
+    WEE_CHECK_EVAL("2", "${hdata_count:buffer[gui_buffers]}");
+    snprintf (str_expr, sizeof (str_expr),
+              "${hdata_count:buffer[%p]}", gui_buffers);
+    WEE_CHECK_EVAL("2", "${hdata_count:buffer[gui_buffers]}");
+    snprintf (str_expr, sizeof (str_expr),
+              "${hdata_count:buffer[%p]}", test_buffer);
+    WEE_CHECK_EVAL("1", str_expr);
+    gui_buffer_close (test_buffer);
+
     /* test hdata */
     hashtable_set (pointers, "my_null_pointer", (const void *)0x0);
     hashtable_set (pointers, "my_buffer_pointer", gui_buffers);