diff --git a/Marlin/src/libs/stopwatch.cpp b/Marlin/src/libs/stopwatch.cpp
index 4178807951..8790c2b3db 100644
--- a/Marlin/src/libs/stopwatch.cpp
+++ b/Marlin/src/libs/stopwatch.cpp
@@ -29,9 +29,9 @@
 #endif
 
 Stopwatch::State Stopwatch::state;
-millis_t Stopwatch::accumulator;
-millis_t Stopwatch::startTimestamp;
-millis_t Stopwatch::stopTimestamp;
+uint32_t Stopwatch::accumulator;
+uint32_t Stopwatch::startTimestamp;
+uint32_t Stopwatch::stopTimestamp;
 
 bool Stopwatch::stop() {
   debug(F("stop"));
@@ -73,7 +73,7 @@ bool Stopwatch::start() {
   else return false;
 }
 
-void Stopwatch::resume(const millis_t with_time) {
+void Stopwatch::resume(const uint32_t with_time) {
   debug(F("resume"));
 
   reset();
@@ -89,7 +89,7 @@ void Stopwatch::reset() {
   accumulator = 0;
 }
 
-millis_t Stopwatch::duration() {
+uint32_t Stopwatch::duration() {
   return accumulator + MS_TO_SEC((isRunning() ? millis() : stopTimestamp) - startTimestamp);
 }
 
diff --git a/Marlin/src/libs/stopwatch.h b/Marlin/src/libs/stopwatch.h
index 829d510050..13fa3de4b4 100644
--- a/Marlin/src/libs/stopwatch.h
+++ b/Marlin/src/libs/stopwatch.h
@@ -36,9 +36,9 @@ class Stopwatch {
     enum State : char { STOPPED, RUNNING, PAUSED };
 
     static Stopwatch::State state;
-    static millis_t accumulator;
-    static millis_t startTimestamp;
-    static millis_t stopTimestamp;
+    static uint32_t accumulator;        // (seconds)
+    static uint32_t startTimestamp;
+    static uint32_t stopTimestamp;
 
   public:
     /**
@@ -75,7 +75,7 @@ class Stopwatch {
      * @brief Resume the stopwatch
      * @details Resume a timer from a given duration
      */
-    static void resume(const millis_t with_time);
+    static void resume(const uint32_t with_time);
 
     /**
      * @brief Reset the stopwatch
@@ -102,7 +102,7 @@ class Stopwatch {
      * @details Return the total number of seconds the timer has been running.
      * @return the delta since starting the stopwatch
      */
-    static millis_t duration();
+    static uint32_t duration();
 
     #ifdef DEBUG_STOPWATCH
 
diff --git a/Marlin/src/module/printcounter.cpp b/Marlin/src/module/printcounter.cpp
index ec5bd8c456..89e3716543 100644
--- a/Marlin/src/module/printcounter.cpp
+++ b/Marlin/src/module/printcounter.cpp
@@ -69,12 +69,12 @@ printStatistics PrintCounter::data;
 
 const PrintCounter::eeprom_address_t PrintCounter::address = STATS_EEPROM_ADDRESS;
 
-millis_t PrintCounter::lastDuration;
+uint32_t PrintCounter::lastDuration;
 bool PrintCounter::loaded = false;
 
-millis_t PrintCounter::deltaDuration() {
+uint32_t PrintCounter::deltaDuration() {
   TERN_(DEBUG_PRINTCOUNTER, debug(PSTR("deltaDuration")));
-  millis_t tmp = lastDuration;
+  const uint32_t tmp = lastDuration;
   lastDuration = duration();
   return lastDuration - tmp;
 }
@@ -236,25 +236,24 @@ void PrintCounter::showStats() {
 void PrintCounter::tick() {
   if (!isRunning()) return;
 
-  millis_t now = millis();
-
+  const millis_t now = millis();
   static millis_t update_next; // = 0
   if (ELAPSED(now, update_next)) {
     update_next = now + updateInterval;
 
     TERN_(DEBUG_PRINTCOUNTER, debug(PSTR("tick")));
 
-    millis_t delta = deltaDuration();
-    data.printTime += delta;
+    const uint32_t delta_s = deltaDuration();
+    data.printTime += delta_s;
 
     #if SERVICE_INTERVAL_1 > 0
-      data.nextService1 -= _MIN(delta, data.nextService1);
+      data.nextService1 -= _MIN(delta_s, data.nextService1);
     #endif
     #if SERVICE_INTERVAL_2 > 0
-      data.nextService2 -= _MIN(delta, data.nextService2);
+      data.nextService2 -= _MIN(delta_s, data.nextService2);
     #endif
     #if SERVICE_INTERVAL_3 > 0
-      data.nextService3 -= _MIN(delta, data.nextService3);
+      data.nextService3 -= _MIN(delta_s, data.nextService3);
     #endif
   }
 
diff --git a/Marlin/src/module/printcounter.h b/Marlin/src/module/printcounter.h
index ebf61a3a1c..dd8d6fbf62 100644
--- a/Marlin/src/module/printcounter.h
+++ b/Marlin/src/module/printcounter.h
@@ -35,13 +35,13 @@ struct printStatistics {    // 16 bytes
   //const uint8_t magic;    // Magic header, it will always be 0x16
   uint16_t totalPrints;     // Number of prints
   uint16_t finishedPrints;  // Number of complete prints
-  uint32_t printTime;       // Accumulated printing time
-  uint32_t longestPrint;    // Longest successful print job
+  uint32_t printTime;       // (s) Accumulated printing time
+  uint32_t longestPrint;    // (s) Longest successful print job
   #if HAS_EXTRUDERS
     float  filamentUsed;    // Accumulated filament consumed in mm
   #endif
   #if SERVICE_INTERVAL_1 > 0
-    uint32_t nextService1;  // Service intervals (or placeholders)
+    uint32_t nextService1;  // (s) Service intervals (or placeholders)
   #endif
   #if SERVICE_INTERVAL_2 > 0
     uint32_t nextService2;
@@ -86,7 +86,7 @@ class PrintCounter: public Stopwatch {
      * @details Store the timestamp of the last deltaDuration(), this is
      * required due to the updateInterval cycle.
      */
-    static millis_t lastDuration;
+    static uint32_t lastDuration;
 
     /**
      * @brief Stats were loaded from EEPROM
@@ -102,7 +102,7 @@ class PrintCounter: public Stopwatch {
      * used internally for print statistics accounting is not intended to be a
      * user callable function.
      */
-    static millis_t deltaDuration();
+    static uint32_t deltaDuration();
 
   public: