diff --git a/Lib/test/test_clinic.py b/Lib/test/test_clinic.py
index d07447d66571e5..76df4f23a49a68 100644
--- a/Lib/test/test_clinic.py
+++ b/Lib/test/test_clinic.py
@@ -3569,6 +3569,7 @@ def test_cli_converters(self):
             "DWORD",
             "fildes",
             "float",
+            "gid_t",
             "HANDLE",
             "int",
             "long",
@@ -3587,6 +3588,7 @@ def test_cli_converters(self):
             "size_t",
             "slice_index",
             "str",
+            "uid_t",
             "uint16",
             "uint32",
             "uint64",
diff --git a/Lib/test/test_pwd.py b/Lib/test/test_pwd.py
index 82acce85f1db57..2ad89444348376 100644
--- a/Lib/test/test_pwd.py
+++ b/Lib/test/test_pwd.py
@@ -61,8 +61,8 @@ def test_errors(self):
         self.assertRaises(TypeError, pwd.getpwuid, 0.0)
         self.assertRaises(TypeError, pwd.getpwuid, 0, 0)
         # should be out of uid_t range
-        self.assertRaises(KeyError, pwd.getpwuid, 2**128)
-        self.assertRaises(KeyError, pwd.getpwuid, -2**128)
+        self.assertRaises(OverflowError, pwd.getpwuid, 2**128)
+        self.assertRaises(OverflowError, pwd.getpwuid, -2**128)
         self.assertRaises(TypeError, pwd.getpwnam)
         self.assertRaises(TypeError, pwd.getpwnam, 42)
         self.assertRaises(TypeError, pwd.getpwnam, b'root')
diff --git a/Misc/NEWS.d/next/Library/2026-08-22-19-00-00.gh-issue-156261.Nq4tWv.rst b/Misc/NEWS.d/next/Library/2026-08-22-19-00-00.gh-issue-156261.Nq4tWv.rst
new file mode 100644
index 00000000000000..a641f8371b368f
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-08-22-19-00-00.gh-issue-156261.Nq4tWv.rst
@@ -0,0 +1,3 @@
+:func:`pwd.getpwuid` now raises :exc:`OverflowError` instead of
+:exc:`KeyError` if the user id is out of the range of the C ``uid_t`` type,
+as :func:`grp.getgrgid` does for the group id.
diff --git a/Misc/NEWS.d/next/Tools-Demos/2026-08-23-18-10-00.gh-issue-156261.Rw8pKd.rst b/Misc/NEWS.d/next/Tools-Demos/2026-08-23-18-10-00.gh-issue-156261.Rw8pKd.rst
index da5e42dfa74429..d2f55f626f6d32 100644
--- a/Misc/NEWS.d/next/Tools-Demos/2026-08-23-18-10-00.gh-issue-156261.Rw8pKd.rst
+++ b/Misc/NEWS.d/next/Tools-Demos/2026-08-23-18-10-00.gh-issue-156261.Rw8pKd.rst
@@ -1,3 +1,3 @@
-Argument Clinic: the ``pid_t``, ``Py_off_t``, ``HANDLE``, ``DWORD`` and
-``BOOL`` converters, previously defined in 9 different files, are now
-provided by Argument Clinic itself.
+Argument Clinic: the ``pid_t``, ``uid_t``, ``gid_t``, ``Py_off_t``,
+``HANDLE``, ``DWORD`` and ``BOOL`` converters, previously defined in
+individual files, are now provided by Argument Clinic itself.
diff --git a/Modules/clinic/grpmodule.c.h b/Modules/clinic/grpmodule.c.h
index 665c2f2dfdac14..9f1ea181d9bc4c 100644
--- a/Modules/clinic/grpmodule.c.h
+++ b/Modules/clinic/grpmodule.c.h
@@ -20,7 +20,7 @@ PyDoc_STRVAR(grp_getgrgid__doc__,
     {"getgrgid", _PyCFunction_CAST(grp_getgrgid), METH_FASTCALL|METH_KEYWORDS, grp_getgrgid__doc__},
 
 static PyObject *
-grp_getgrgid_impl(PyObject *module, PyObject *id);
+grp_getgrgid_impl(PyObject *module, gid_t gid);
 
 static PyObject *
 grp_getgrgid(PyObject *module, PyObject *const *args, Py_ssize_t nargs, PyObject *kwnames)
@@ -54,15 +54,17 @@ grp_getgrgid(PyObject *module, PyObject *const *args, Py_ssize_t nargs, PyObject
     };
     #undef KWTUPLE
     PyObject *argsbuf[1];
-    PyObject *id;
+    gid_t gid;
 
     args = _PyArg_UnpackKeywords(args, nargs, NULL, kwnames, &_parser,
             /*minpos*/ 1, /*maxpos*/ 1, /*minkw*/ 0, /*varpos*/ 0, argsbuf);
     if (!args) {
         goto exit;
     }
-    id = args[0];
-    return_value = grp_getgrgid_impl(module, id);
+    if (!_Py_Gid_Converter(args[0], &gid)) {
+        goto exit;
+    }
+    return_value = grp_getgrgid_impl(module, gid);
 
 exit:
     return return_value;
@@ -152,4 +154,4 @@ grp_getgrall(PyObject *module, PyObject *Py_UNUSED(ignored))
 {
     return grp_getgrall_impl(module);
 }
-/*[clinic end generated code: output=35aa81c00dbd3229 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=9052db62d986262c input=a9049054013a1b77]*/
diff --git a/Modules/clinic/pwdmodule.c.h b/Modules/clinic/pwdmodule.c.h
index 43d4825031c7e6..64127ff8e494db 100644
--- a/Modules/clinic/pwdmodule.c.h
+++ b/Modules/clinic/pwdmodule.c.h
@@ -15,6 +15,24 @@ PyDoc_STRVAR(pwd_getpwuid__doc__,
 #define PWD_GETPWUID_METHODDEF    \
     {"getpwuid", (PyCFunction)pwd_getpwuid, METH_O, pwd_getpwuid__doc__},
 
+static PyObject *
+pwd_getpwuid_impl(PyObject *module, uid_t uid);
+
+static PyObject *
+pwd_getpwuid(PyObject *module, PyObject *arg)
+{
+    PyObject *return_value = NULL;
+    uid_t uid;
+
+    if (!_Py_Uid_Converter(arg, &uid)) {
+        goto exit;
+    }
+    return_value = pwd_getpwuid_impl(module, uid);
+
+exit:
+    return return_value;
+}
+
 PyDoc_STRVAR(pwd_getpwnam__doc__,
 "getpwnam($module, name, /)\n"
 "--\n"
@@ -73,4 +91,4 @@ pwd_getpwall(PyObject *module, PyObject *Py_UNUSED(ignored))
 #ifndef PWD_GETPWALL_METHODDEF
     #define PWD_GETPWALL_METHODDEF
 #endif /* !defined(PWD_GETPWALL_METHODDEF) */
-/*[clinic end generated code: output=5a8fb12939ff4ea3 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=5bca0b2c2f4c5e89 input=a9049054013a1b77]*/
diff --git a/Modules/grpmodule.c b/Modules/grpmodule.c
index 32ead259803614..fe1d16d8322005 100644
--- a/Modules/grpmodule.c
+++ b/Modules/grpmodule.c
@@ -117,7 +117,7 @@ mkgrent(PyObject *module, struct group *p)
 /*[clinic input]
 grp.getgrgid
 
-    id: object
+    id as gid: gid_t
 
 Return the group database entry for the given numeric group ID.
 
@@ -125,18 +125,14 @@ If id is not valid, raise KeyError.
 [clinic start generated code]*/
 
 static PyObject *
-grp_getgrgid_impl(PyObject *module, PyObject *id)
-/*[clinic end generated code: output=30797c289504a1ba input=15fa0e2ccf5cda25]*/
+grp_getgrgid_impl(PyObject *module, gid_t gid)
+/*[clinic end generated code: output=a9e7385cd6df08da input=fca15128dd772588]*/
 {
     PyObject *retval = NULL;
     int nomem = 0;
     char *buf = NULL, *buf2 = NULL;
-    gid_t gid;
     struct group *p;
 
-    if (!_Py_Gid_Converter(id, &gid)) {
-        return NULL;
-    }
 #ifdef HAVE_GETGRGID_R
     int status;
     Py_ssize_t bufsize;
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index a9375e48a11d89..9724187dda4bb6 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -3185,14 +3185,6 @@ class dir_fd_converter(CConverter):
     def c_default_init(self):
         self.c_default = 'DEFAULT_DIR_FD'
 
-class uid_t_converter(CConverter):
-    type = "uid_t"
-    converter = '_Py_Uid_Converter'
-
-class gid_t_converter(CConverter):
-    type = "gid_t"
-    converter = '_Py_Gid_Converter'
-
 class dev_t_converter(CConverter):
     type = 'dev_t'
     converter = '_Py_Dev_Converter'
@@ -3249,7 +3241,7 @@ class confname_converter(CConverter):
         """, argname=argname, converter=self.converter, table=self.table)
 
 [python start generated code]*/
-/*[python end generated code: output=da39a3ee5e6b4b0d input=e459765bdf453ebf]*/
+/*[python end generated code: output=da39a3ee5e6b4b0d input=7ceccf55bb600f61]*/
 
 /*[clinic input]
 
diff --git a/Modules/pwdmodule.c b/Modules/pwdmodule.c
index 4a2b33f8700d10..be5e0d4d0c29ae 100644
--- a/Modules/pwdmodule.c
+++ b/Modules/pwdmodule.c
@@ -121,7 +121,7 @@ mkpwent(PyObject *module, struct passwd *p)
 /*[clinic input]
 pwd.getpwuid
 
-    uidobj: object
+    uidobj as uid: uid_t
     /
 
 Return the password database entry for the given numeric user ID.
@@ -130,21 +130,14 @@ See `help(pwd)` for more on password database entries.
 [clinic start generated code]*/
 
 static PyObject *
-pwd_getpwuid(PyObject *module, PyObject *uidobj)
-/*[clinic end generated code: output=c4ee1d4d429b86c4 input=ae64d507a1c6d3e8]*/
+pwd_getpwuid_impl(PyObject *module, uid_t uid)
+/*[clinic end generated code: output=631bad376fa670c3 input=506d3a592ef19799]*/
 {
     PyObject *retval = NULL;
-    uid_t uid;
     int nomem = 0;
     struct passwd *p;
     char *buf = NULL, *buf2 = NULL;
 
-    if (!_Py_Uid_Converter(uidobj, &uid)) {
-        if (PyErr_ExceptionMatches(PyExc_OverflowError))
-            PyErr_Format(PyExc_KeyError,
-                         "getpwuid(): uid not found");
-        return NULL;
-    }
 #ifdef HAVE_GETPWUID_R
     int status;
     Py_ssize_t bufsize;
diff --git a/Tools/clinic/libclinic/converters.py b/Tools/clinic/libclinic/converters.py
index c2ac6fd22d5bdc..5f663a50ab8ce8 100644
--- a/Tools/clinic/libclinic/converters.py
+++ b/Tools/clinic/libclinic/converters.py
@@ -601,6 +601,16 @@ def parse_arg(self, argname: str, displayname: str, *, limited_capi: bool) -> st
             argname=argname)
 
 
+class gid_t_converter(CConverter):
+    type = 'gid_t'
+    converter = '_Py_Gid_Converter'
+
+
+class uid_t_converter(CConverter):
+    type = 'uid_t'
+    converter = '_Py_Uid_Converter'
+
+
 class pid_t_converter(CConverter):
     type = 'pid_t'
     format_unit = '" _Py_PARSE_PID "'