diff --git a/web/src/endpoints/availability/get_new.rs b/web/src/endpoints/availability/get_new.rs
index 7a6e579c..fca70341 100644
--- a/web/src/endpoints/availability/get_new.rs
+++ b/web/src/endpoints/availability/get_new.rs
@@ -2,9 +2,10 @@ use actix_web::{web, HttpResponse, Responder};
 use chrono::NaiveDate;
 use rinja::Template;
 use serde::Deserialize;
+use sqlx::PgPool;
 
-use crate::endpoints::availability::NewOrEditAvailabilityTemplate;
-use crate::models::User;
+use crate::endpoints::availability::{calc_free_slots_cor, NewOrEditAvailabilityTemplate};
+use crate::models::{Availabillity, User};
 use crate::utils::ApplicationError;
 
 #[derive(Deserialize)]
@@ -17,8 +18,32 @@ struct AvailabilityNewQuery {
 #[actix_web::get("/availabillity/new")]
 pub async fn get(
     user: web::ReqData<User>,
+    pool: web::Data<PgPool>,
     query: web::Query<AvailabilityNewQuery>,
 ) -> Result<impl Responder, ApplicationError> {
+    let availabillities = Availabillity::read_by_date_and_area_including_user(
+        pool.get_ref(),
+        query.date,
+        user.area_id,
+    )
+    .await?;
+
+    let availabilities_from_user: Vec<&Availabillity> = availabillities
+        .iter()
+        .filter(|a| a.user_id == user.id)
+        .collect();
+    let only_one_availability_is_wholeday = availabilities_from_user.len() == 1
+        && availabilities_from_user[0].start_time.is_none()
+        && availabilities_from_user[0].end_time.is_none();
+
+    let user_can_create_availabillity = availabilities_from_user.len() == 0
+        || !(only_one_availability_is_wholeday
+            || calc_free_slots_cor(&availabilities_from_user).len() == 0);
+
+    if !user_can_create_availabillity {
+        return Ok(HttpResponse::BadRequest().finish());
+    }
+
     let template = NewOrEditAvailabilityTemplate {
         user: user.into_inner(),
         date: query.date,
@@ -27,6 +52,7 @@ pub async fn get(
         start_time: None,
         end_time: None,
         comment: None,
+        slot_suggestions: calc_free_slots_cor(&availabilities_from_user),
     };
 
     Ok(HttpResponse::Ok().body(template.render()?))
diff --git a/web/src/endpoints/availability/get_overview.rs b/web/src/endpoints/availability/get_overview.rs
index c0949d98..0519aca0 100644
--- a/web/src/endpoints/availability/get_overview.rs
+++ b/web/src/endpoints/availability/get_overview.rs
@@ -1,10 +1,8 @@
 use crate::{
-    filters,
-    models::{Assignment, Function, Vehicle},
-    utils::{event_planning_template::generate_vehicles_assigned_and_available, ApplicationError},
+    endpoints::availability::calc_free_slots_cor, filters, models::{Assignment, Function, Vehicle}, utils::{event_planning_template::generate_vehicles_assigned_and_available, ApplicationError}
 };
 use actix_web::{web, HttpResponse, Responder};
-use chrono::{NaiveDate, Utc};
+use chrono::{NaiveDate, NaiveTime, Utc};
 use rinja::Template;
 use serde::Deserialize;
 use sqlx::PgPool;
@@ -21,10 +19,17 @@ pub struct CalendarQuery {
 #[template(path = "index.html")]
 struct CalendarTemplate {
     user: User,
+    user_can_create_availabillity: bool,
     date: NaiveDate,
     selected_area: Option<i32>,
     areas: Vec<Area>,
-    events_and_assignments: Vec<(Event, Vec<String>, Option<String>, Option<String>, Vec<Vehicle>)>,
+    events_and_assignments: Vec<(
+        Event,
+        Vec<String>,
+        Option<String>,
+        Option<String>,
+        Vec<Vehicle>,
+    )>,
     availabillities: Vec<Availabillity>,
 }
 
@@ -59,6 +64,18 @@ async fn get(
     )
     .await?;
 
+    let availabilities_from_user: Vec<&Availabillity> = availabillities
+        .iter()
+        .filter(|a| a.user_id == user.id)
+        .collect();
+    let only_one_availability_is_wholeday = availabilities_from_user.len() == 1
+        && availabilities_from_user[0].start_time.is_none()
+        && availabilities_from_user[0].end_time.is_none();
+
+    let user_can_create_availabillity = availabilities_from_user.len() == 0
+        || !(only_one_availability_is_wholeday
+            || calc_free_slots_cor(&availabilities_from_user).len() == 0);
+
     let mut events_and_assignments = Vec::new();
     for e in Event::read_all_by_date_and_area_including_location(
         pool.get_ref(),
@@ -120,12 +137,13 @@ async fn get(
                         .clone(),
                 )
             }),
-            assigned_vehicle
+            assigned_vehicle,
         ));
     }
 
     let template = CalendarTemplate {
         user: user.into_inner(),
+        user_can_create_availabillity,
         date,
         selected_area,
         areas,
diff --git a/web/src/endpoints/availability/get_update.rs b/web/src/endpoints/availability/get_update.rs
index 669e5786..dd191c41 100644
--- a/web/src/endpoints/availability/get_update.rs
+++ b/web/src/endpoints/availability/get_update.rs
@@ -4,7 +4,10 @@ use serde::Deserialize;
 use sqlx::PgPool;
 
 use crate::{
-    endpoints::{availability::NewOrEditAvailabilityTemplate, IdPath},
+    endpoints::{
+        availability::{calc_free_slots_cor, NewOrEditAvailabilityTemplate},
+        IdPath,
+    },
     models::{Availabillity, User},
     utils::ApplicationError,
 };
@@ -40,6 +43,29 @@ pub async fn get(
 
     let has_time = availabillity.start_time.is_some() && availabillity.end_time.is_some();
 
+    let suggestions = if has_time {
+        let availabillities = Availabillity::read_by_date_and_area_including_user(
+            pool.get_ref(),
+            availabillity.date,
+            user.area_id,
+        )
+        .await?;
+
+        let availabilities_from_user: Vec<&Availabillity> = availabillities
+            .iter()
+            .filter(|a| a.user_id == user.id)
+            .collect();
+
+        calc_free_slots_cor(&availabilities_from_user)
+            .into_iter()
+            .filter(|(a, b)| {
+                *b == availabillity.start_time.unwrap() || *a == availabillity.end_time.unwrap()
+            })
+            .collect()
+    } else {
+        Vec::new()
+    };
+
     let template = NewOrEditAvailabilityTemplate {
         user: user.into_inner(),
         date: availabillity.date,
@@ -48,6 +74,7 @@ pub async fn get(
         start_time: start_time.as_deref(),
         end_time: end_time.as_deref(),
         comment: availabillity.comment.as_deref(),
+        slot_suggestions: suggestions,
     };
 
     Ok(HttpResponse::Ok().body(template.render()?))
diff --git a/web/src/endpoints/availability/mod.rs b/web/src/endpoints/availability/mod.rs
index d96667be..5affa8ee 100644
--- a/web/src/endpoints/availability/mod.rs
+++ b/web/src/endpoints/availability/mod.rs
@@ -1,8 +1,8 @@
+use chrono::{NaiveDate, NaiveTime};
 use rinja::Template;
-use chrono::NaiveDate;
 
 use crate::filters;
-use crate::models::{Role, User};
+use crate::models::{Availabillity, Role, User};
 
 pub mod delete;
 pub mod get_new;
@@ -21,4 +21,72 @@ struct NewOrEditAvailabilityTemplate<'a> {
     start_time: Option<&'a str>,
     end_time: Option<&'a str>,
     comment: Option<&'a str>,
+    slot_suggestions: Vec<(NaiveTime, NaiveTime)>,
+}
+
+fn calc_free_slots_cor(availabilities: &Vec<&Availabillity>) -> Vec<(NaiveTime, NaiveTime)> {
+    let mut times = Vec::new();
+
+    for a in availabilities {
+        let Some(start_time) = a.start_time else {
+            continue;
+        };
+
+        let Some(end_time) = a.end_time else {
+            continue;
+        };
+
+        times.push((start_time, end_time));
+    }
+
+    if times.len() == 0 {
+        return Vec::new();
+    }
+    println!("zeiten {times:?}");
+
+    times.sort();
+
+    println!("zeiten sort {times:?}");
+
+    let mut changed = true;
+    while changed {
+        changed = false;
+
+        for i in 0..(times.len() - 1) {
+            let b = times[i + 1].clone();
+            let a = times.get_mut(i).unwrap();
+
+            if a.1 == b.0 {
+                a.1 = b.1;
+                times.remove(i + 1);
+                changed = true;
+                break;
+            }
+        }
+    }
+
+    let start = NaiveTime::parse_from_str("00:00", "%R").unwrap();
+    let end = NaiveTime::parse_from_str("23:59", "%R").unwrap();
+    println!("zeiten unified {times:?}");
+
+    // now times contains unified list of existing availabilities -> now calculate the "inverse"
+
+    let mut available_slots = Vec::new();
+    if times.first().unwrap().0 != start {
+        available_slots.push((start, times.first().unwrap().0));
+    }
+
+    let mut iterator = times.iter().peekable();
+    while let Some(a) = iterator.next() {
+        if let Some(b) = iterator.peek() {
+            available_slots.push((a.1, b.0));
+        }
+    }
+
+    if times.last().unwrap().1 != end {
+        available_slots.push((times.last().unwrap().1, end));
+    }
+
+    println!("available {available_slots:?}");
+    available_slots
 }
diff --git a/web/src/models/availabillity.rs b/web/src/models/availabillity.rs
index 97d60198..d28bafdd 100644
--- a/web/src/models/availabillity.rs
+++ b/web/src/models/availabillity.rs
@@ -1,5 +1,3 @@
-use std::fmt::Display;
-
 use chrono::{NaiveDate, NaiveTime};
 use sqlx::{query, PgPool};
 
@@ -30,18 +28,6 @@ pub enum AvailabillityAssignmentState {
     AssignedWachhabender(i32),
 }
 
-impl Display for AvailabillityAssignmentState {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        match self {
-            AvailabillityAssignmentState::Unassigned => write!(f, "nicht zugewiesen"),
-            AvailabillityAssignmentState::Conflicting => write!(f, "bereits anders zugewiesen"),
-            AvailabillityAssignmentState::AssignedPosten(_) => write!(f, "zugewiesen als Posten"),
-            AvailabillityAssignmentState::AssignedFührungsassistent(_) => write!(f, "zugewiesen als Führungsassistent"),
-            AvailabillityAssignmentState::AssignedWachhabender(_) => write!(f, "zugewiesen als Wachhabender"),
-        }
-    }
-}
-
 impl Availabillity {
     pub async fn create(
         pool: &PgPool,
diff --git a/web/templates/availability/new_or_edit.html b/web/templates/availability/new_or_edit.html
index e7d34f76..ccef9a96 100644
--- a/web/templates/availability/new_or_edit.html
+++ b/web/templates/availability/new_or_edit.html
@@ -52,6 +52,12 @@
             <div class="field">
               <input class="input" type="time" id="from" name="from" value='{{ start_time.unwrap_or("00:00") }}' {{
                 whole_day|cond_show("disabled") }} {{ whole_day|invert|ref|cond_show("required") }}>
+              <p class="help">noch mögliche Zeiträume:</p>
+              <div class="tags help">
+                {% for (s, e) in slot_suggestions %}
+                <span class="tag">{{ s }} - {{ e }}</span>
+                {% endfor %}
+              </div>
             </div>
             <div class="field">
               <input class="input" type="time" id="till" name="till" value='{{ end_time.unwrap_or("23:59") }}' {{
diff --git a/web/templates/index.html b/web/templates/index.html
index 5dcd8ea4..ae7f9397 100644
--- a/web/templates/index.html
+++ b/web/templates/index.html
@@ -183,12 +183,14 @@
         </div>
         {% if selected_area.is_none() || selected_area.unwrap() == user.area_id %}
         <div class="level-right">
-          <a class="button is-link is-light" hx-boost="true" href="/availabillity/new?date={{ date }}">
+          {% let btn_disabled = !user_can_create_availabillity %}
+          <button class="button is-link is-light" hx-get="/availabillity/new?date={{ date }}" {{
+            btn_disabled|cond_show("disabled") }} hx-target="closest body">
             <svg class="icon">
               <use href="/static/feather-sprite.svg#plus-circle" />
             </svg>
             <span>Neue Verfügbarkeit für diesen Tag</span>
-          </a>
+          </button>
         </div>
         {% endif %}
       </div>