diff --git a/app/controllers/Clas.scala b/app/controllers/Clas.scala
index dba51ce516..76e131490c 100644
--- a/app/controllers/Clas.scala
+++ b/app/controllers/Clas.scala
@@ -211,25 +211,26 @@ final class Clas(
       Ok(_)
     } else
       WithClassAndStudents(me, id) { (clas, students) =>
-        ctx.req.flash.get("created").map(_ split ' ').?? {
-          case Array(userId, password) =>
-            env.clas.api.student
-              .get(clas, userId)
-              .map2(lila.clas.Student.WithPassword(_, lila.user.User.ClearPassword(password)))
-          case _ => fuccess(none)
-        } flatMap { created =>
-          env.clas.forms.student.generate map { createForm =>
-            Ok(
-              html.clas.student.form(
-                clas,
-                students,
-                env.clas.forms.student.invite(clas),
-                createForm,
-                created
-              )
-            )
+        for {
+          created <- ctx.req.flash.get("created").map(_ split ' ').?? {
+            case Array(userId, password) =>
+              env.clas.api.student
+                .get(clas, userId)
+                .map2(lila.clas.Student.WithPassword(_, lila.user.User.ClearPassword(password)))
+            case _ => fuccess(none)
           }
-        }
+          nbStudents <- env.clas.api.student.count(clas.id)
+          createForm <- env.clas.forms.student.generate
+        } yield Ok(
+          html.clas.student.form(
+            clas,
+            students,
+            env.clas.forms.student.invite(clas),
+            createForm,
+            nbStudents,
+            created
+          )
+        )
       }
   }
 
@@ -241,14 +242,17 @@ final class Clas(
             .bindFromRequest()(ctx.body)
             .fold(
               err =>
-                BadRequest(
-                  html.clas.student.form(
-                    clas,
-                    students,
-                    env.clas.forms.student.invite(clas),
-                    err
+                env.clas.api.student.count(clas.id) map { nbStudents =>
+                  BadRequest(
+                    html.clas.student.form(
+                      clas,
+                      students,
+                      env.clas.forms.student.invite(clas),
+                      err,
+                      nbStudents
+                    )
                   )
-                ).fuccess,
+                },
               data =>
                 env.clas.api.student.create(clas, data, me) map {
                   case (user, password) =>
@@ -268,14 +272,17 @@ final class Clas(
         .bindFromRequest()(ctx.body)
         .fold(
           err =>
-            BadRequest(
-              html.clas.student.form(
-                clas,
-                students,
-                err,
-                env.clas.forms.student.create
+            env.clas.api.student.count(clas.id) map { nbStudents =>
+              BadRequest(
+                html.clas.student.form(
+                  clas,
+                  students,
+                  err,
+                  env.clas.forms.student.create,
+                  nbStudents
+                )
               )
-            ).fuccess,
+            },
           data =>
             env.user.repo named data.username flatMap {
               _ ?? { user =>
diff --git a/app/views/clas/student.scala b/app/views/clas/student.scala
index a5c64de112..9138a7d66a 100644
--- a/app/views/clas/student.scala
+++ b/app/views/clas/student.scala
@@ -113,11 +113,21 @@ object student {
       students: List[Student],
       invite: Form[_],
       create: Form[_],
+      nbStudents: Int,
       created: Option[lila.clas.Student.WithPassword] = none
   )(implicit ctx: Context) =
     bits.layout(trans.clas.addStudent.txt(), Left(c withStudents students))(
       cls := "box-pad student-add",
-      h1(trans.clas.addStudent()),
+      h1(
+        trans.clas.addStudent(),
+        s" ($nbStudents/${lila.clas.Clas.maxStudents})"
+      ),
+      nbStudents > (lila.clas.Clas.maxStudents / 2) option p(dataIcon := "", cls := "text")(
+        s"Note that a class can have up to ${lila.clas.Clas.maxStudents} students.",
+        "To manage more students, ",
+        a(href := routes.Clas.studentForm(c.id.value))("create more classes"),
+        "."
+      ),
       created map {
         case Student.WithPassword(student, password) =>
           flashMessage(cls := "student-add__created")(
@@ -134,51 +144,47 @@ object student {
           )
       },
       standardFlash(),
-      div(cls := "student-add__choice")(
-        div(cls := "info")(
-          h2(trans.clas.inviteALichessAccount()),
-          p(trans.clas.inviteDesc1()),
-          p(trans.clas.inviteDesc2()),
-          p(
-            strong(trans.clas.inviteDesc3()),
-            br,
-            trans.clas.inviteDesc4()
+      (nbStudents <= lila.clas.Clas.maxStudents) option frag(
+        div(cls := "student-add__choice")(
+          div(cls := "info")(
+            h2(trans.clas.inviteALichessAccount()),
+            p(trans.clas.inviteDesc1()),
+            p(trans.clas.inviteDesc2()),
+            p(
+              strong(trans.clas.inviteDesc3()),
+              br,
+              trans.clas.inviteDesc4()
+            )
+          ),
+          postForm(cls := "form3", action := routes.Clas.studentInvite(c.id.value))(
+            form3.group(invite("username"), trans.clas.lichessUsername())(
+              form3.input(_, klass = "user-autocomplete")(created.isEmpty option autofocus)(dataTag := "span")
+            ),
+            realNameField(invite),
+            form3.submit("Invite", icon = none)
           )
         ),
-        postForm(cls := "form3", action := routes.Clas.studentInvite(c.id.value))(
-          form3.group(invite("username"), trans.clas.lichessUsername())(
-            form3.input(_, klass = "user-autocomplete")(created.isEmpty option autofocus)(dataTag := "span")
+        div(cls := "student-add__or")("~ or ~"),
+        div(cls := "student-add__choice")(
+          div(cls := "info")(
+            h2(trans.clas.createANewLichessAccount()),
+            p(trans.clas.createDesc1()),
+            p(trans.clas.createDesc2()),
+            p(strong(trans.clas.createDesc3()), br, trans.clas.createDesc4())
           ),
-          realNameField(invite),
-          form3.submit("Invite", icon = none)
-        )
-      ),
-      div(cls := "student-add__or")("~ or ~"),
-      div(cls := "student-add__choice")(
-        div(cls := "info")(
-          h2(trans.clas.createANewLichessAccount()),
-          p(trans.clas.createDesc1()),
-          p(
-            trans.clas.createDesc2()
-          ),
-          p(
-            strong(trans.clas.createDesc3()),
-            br,
-            trans.clas.createDesc4()
+          postForm(cls := "form3", action := routes.Clas.studentCreate(c.id.value))(
+            form3.group(
+              create("create-username"),
+              trans.clas.lichessUsername(),
+              help = a(cls := "name-regen", href := s"${routes.Clas.studentForm(c.id.value)}?gen=1")(
+                trans.clas.generateANewUsername()
+              ).some
+            )(
+              form3.input(_)(created.isDefined option autofocus)
+            ),
+            realNameField(create, "create-realName"),
+            form3.submit(trans.signUp(), icon = none)
           )
-        ),
-        postForm(cls := "form3", action := routes.Clas.studentCreate(c.id.value))(
-          form3.group(
-            create("create-username"),
-            trans.clas.lichessUsername(),
-            help = a(cls := "name-regen", href := s"${routes.Clas.studentForm(c.id.value)}?gen=1")(
-              trans.clas.generateANewUsername()
-            ).some
-          )(
-            form3.input(_)(created.isDefined option autofocus)
-          ),
-          realNameField(create, "create-realName"),
-          form3.submit(trans.signUp(), icon = none)
         )
       )
     )
diff --git a/modules/clas/src/main/Clas.scala b/modules/clas/src/main/Clas.scala
index ba4ca6a118..dbd8df8464 100644
--- a/modules/clas/src/main/Clas.scala
+++ b/modules/clas/src/main/Clas.scala
@@ -26,6 +26,8 @@ case class Clas(
 
 object Clas {
 
+  val maxStudents = 100
+
   def make(teacher: User, name: String, desc: String) = Clas(
     _id = Id(scala.util.Random.alphanumeric take 8 mkString),
     name = name,
diff --git a/modules/clas/src/main/ClasApi.scala b/modules/clas/src/main/ClasApi.scala
index 6316aad9ad..ef682b833c 100644
--- a/modules/clas/src/main/ClasApi.scala
+++ b/modules/clas/src/main/ClasApi.scala
@@ -122,6 +122,8 @@ final class ClasApi(
         }
       }
 
+    def count(clasId: Clas.Id): Fu[Int] = coll.countSel($doc("clasId" -> clasId))
+
     def isManaged(user: User): Fu[Boolean] =
       coll.exists($doc("userId" -> user.id, "managed" -> true))