diff --git a/esphome/components/sensor/__init__.py b/esphome/components/sensor/__init__.py
index c18aa32f377..ed02cc25438 100644
--- a/esphome/components/sensor/__init__.py
+++ b/esphome/components/sensor/__init__.py
@@ -564,7 +564,12 @@ async def exponential_moving_average_filter_to_code(config, filter_id):
 
 
 @FILTER_REGISTRY.register(
-    "throttle_average", ThrottleAverageFilter, cv.positive_time_period_milliseconds
+    "throttle_average",
+    ThrottleAverageFilter,
+    cv.All(
+        cv.positive_time_period_milliseconds,
+        cv.Range(max=cv.TimePeriod(hours=24)),
+    ),
 )
 async def throttle_average_filter_to_code(config, filter_id):
     return cg.new_Pvariable(filter_id, config)
diff --git a/esphome/components/sensor/filter.h b/esphome/components/sensor/filter.h
index d61df11d9b9..57a2386a7fa 100644
--- a/esphome/components/sensor/filter.h
+++ b/esphome/components/sensor/filter.h
@@ -264,9 +264,12 @@ class ThrottleAverageFilter : public Filter {
 
  protected:
   float sum_{0.0f};
-  unsigned int n_{0};
   uint32_t time_period_;
-  bool have_nan_{false};
+  // Sample count packed with NaN-seen flag in a single 32-bit word.
+  // n_ is bounded by YAML cap on time_period_ (24 h) × max plausible source
+  // rate (1 kHz) = 86.4M ≪ 2^31, so 31 bits has 25x headroom.
+  uint32_t n_ : 31 {0};
+  uint32_t have_nan_ : 1 {0};
 };
 
 using lambda_filter_t = std::function<optional<float>(float)>;