diff --git a/stepper.c b/stepper.c
index 8acc1f8..214c8fc 100644
--- a/stepper.c
+++ b/stepper.c
@@ -95,6 +95,11 @@ static float cycles_per_min;
 static volatile segment_t *segment_buffer_tail;
 static segment_t *segment_buffer_head, *segment_next_head;
 
+#if ENABLE_JERK_ACCELERATION
+// Static storage for acceleration value of last computed segment.   
+static float last_segment_accel = 0.0f;
+#endif
+
 // Pointers for the step segment being prepped from the planner buffer. Accessed only by the
 // main program. Pointers may be planning segments or planner blocks ahead of what being executed.
 static plan_block_t *pl_block;     // Pointer to the planner block being prepped
@@ -866,13 +871,14 @@ void st_prep_buffer (void)
         float dt_max = DT_SEGMENT; // Maximum segment time
         float dt = 0.0f; // Initialize segment time
         float time_var = dt_max; // Time worker variable
-#if ENABLE_JERK_ACCELERATION   
-        float last_segment_accel = 0.0f; // Acceleration value of last computed segment. Initialize as 0.0
-#endif
         float mm_var; // mm - Distance worker variable
         float speed_var; // Speed worker variable
         float mm_remaining = pl_block->millimeters; // New segment distance from end of block.
         float minimum_mm = mm_remaining - prep.req_mm_increment; // Guarantee at least one step.
+#if ENABLE_ACCELERATION_PROFILES
+        float time_to_jerk;     // time needed for jerk ramp
+        float mm_to_rampend;    // mm needed to complete one jerk ramp mm == V(0)*T + 1/2 A0*T^2 + 1/6 J*T^3
+#endif
 
         if (minimum_mm < 0.0f)
             minimum_mm = 0.0f;
@@ -897,15 +903,17 @@ void st_prep_buffer (void)
 
                 case Ramp_Accel:
                     // NOTE: Acceleration ramp only computes during first do-while loop.
-#if ENABLE_JERK_ACCELERATION   
-                    if (((mm_remaining - prep.accelerate_until) / (prep.current_speed + 0.001f)) <= (last_segment_accel / pl_block->jerk)) { 
-                        //+0.001f to avoid divide by 0 speed, minor effect on jerk ramp (+1.0f was too large for low jerk values)
+#if ENABLE_JERK_ACCELERATION
+                    time_to_jerk = last_segment_accel / pl_block->jerk;
+                    mm_to_rampend = (prep.current_speed * time_to_jerk) + (0.5f * last_segment_accel * time_to_jerk * time_to_jerk) + (pl_block->jerk * time_to_jerk * time_to_jerk * time_to_jerk) / 6.0f;
+                    if ((mm_remaining - prep.accelerate_until) > mm_to_rampend) {
+                        //+1.0f to avoid divide by 0 speed, minor effect on jerk ramp
                         // Check if we are on ramp up or ramp down. Ramp down if time to end of acceleration is less than time needed to reach 0 acceleration.
                         // Then limit acceleration change by jerk up to max acceleration and update for next segment.
-                        // Minimum acceleration jerk per time_var to ensure acceleartion completes. Acceleration change at end of ramp is in acceptable jerk range.
-                        last_segment_accel = max(last_segment_accel - pl_block->jerk * time_var, pl_block->jerk * time_var); 
-                    } else {
+                        // Minimum acceleration jerk per time_var to ensure acceleration completes. Acceleration change at end of ramp is in acceptable jerk range.
                         last_segment_accel = min(last_segment_accel + pl_block->jerk * time_var, pl_block->max_acceleration); 
+                    } else {
+                        last_segment_accel = max(last_segment_accel - pl_block->jerk * time_var, pl_block->jerk * time_var);  
                     }
                     speed_var = last_segment_accel * time_var;
 #else
@@ -942,14 +950,15 @@ void st_prep_buffer (void)
                 default: // case Ramp_Decel:
                     // NOTE: mm_var used as a misc worker variable to prevent errors when near zero speed.
 #if ENABLE_JERK_ACCELERATION   
-                    if ((mm_remaining / (prep.current_speed + 0.001f)) <= (last_segment_accel / pl_block->jerk)) { 
-                        //+0.001f to avoid divide by 0 speed, minor effect on jerk ramp (+1.0f was too large for low jerk values)
-                        // Check if we are on ramp up or ramp down. Ramp down if time to end of deceleration is less than time needed to reach 0 acceleration.
+                    time_to_jerk = last_segment_accel / pl_block->jerk;
+                    mm_to_rampend = (prep.current_speed * time_to_jerk) + (0.5f * last_segment_accel * time_to_jerk * time_to_jerk) + (pl_block->jerk * time_to_jerk * time_to_jerk * time_to_jerk) / 6.0f;
+                    if (mm_remaining > mm_to_rampend) {
+                        // Check if we are on ramp up or ramp down. Ramp down if travel distance to end of deceleration is less than distance needed to reach 0 acceleration.
                         // Then limit acceleration change by jerk up to max acceleration and update for next segment.
                         // Minimum acceleration of jerk per time_var to ensure acceleration completes. Acceleration change at end of ramp is in acceptable jerk range.
-                        last_segment_accel = max(last_segment_accel - pl_block->jerk * time_var, pl_block->jerk * time_var); 
-                    } else {
                         last_segment_accel = min(last_segment_accel + pl_block->jerk * time_var, pl_block->max_acceleration); 
+                    } else {
+                        last_segment_accel = max(last_segment_accel - pl_block->jerk * time_var, pl_block->jerk * time_var);  
                     }
                     speed_var = last_segment_accel * time_var; // Used as delta speed (mm/min)
 #else
@@ -968,6 +977,9 @@ void st_prep_buffer (void)
                     time_var = 2.0f * (mm_remaining - prep.mm_complete) / (prep.current_speed + prep.exit_speed);
                     mm_remaining = prep.mm_complete;
                     prep.current_speed = prep.exit_speed;
+#if ENABLE_JERK_ACCELERATION
+                    last_segment_accel = 0.0f;  // reset acceleration variable to 0 for next accel ramp
+#endif
             }
 
             dt += time_var; // Add computed ramp time to total segment time.