diff --git a/src/all_gather.cu b/src/all_gather.cu
index 0831207433..6db67e6d00 100644
--- a/src/all_gather.cu
+++ b/src/all_gather.cu
@@ -7,10 +7,8 @@
 #include "cuda_runtime.h"
 #include "common.h"
 
-#define ALIGN 4
-
-void AllGatherGetCollByteCount(size_t *sendcount, size_t *recvcount, size_t *paramcount, size_t *sendInplaceOffset, size_t *recvInplaceOffset, size_t count, int nranks) {
-  size_t base = (count/(ALIGN*nranks))*ALIGN;
+void AllGatherGetCollByteCount(size_t *sendcount, size_t *recvcount, size_t *paramcount, size_t *sendInplaceOffset, size_t *recvInplaceOffset, size_t count, size_t eltSize, int nranks) {
+  size_t base = (count/nranks) & -(16/eltSize);
   *sendcount = base;
   *recvcount = base*nranks;
   *sendInplaceOffset = base;
@@ -60,7 +58,7 @@ struct testColl allGatherTest = {
 
 void AllGatherGetBuffSize(size_t *sendcount, size_t *recvcount, size_t count, int nranks) {
   size_t paramcount, sendInplaceOffset, recvInplaceOffset;
-  AllGatherGetCollByteCount(sendcount, recvcount, &paramcount, &sendInplaceOffset, &recvInplaceOffset, count, nranks);
+  AllGatherGetCollByteCount(sendcount, recvcount, &paramcount, &sendInplaceOffset, &recvInplaceOffset, count, /*eltSize=*/1, nranks);
 }
 
 testResult_t AllGatherRunTest(struct threadArgs* args, int root, ncclDataType_t type, const char* typeName, ncclRedOp_t op, const char* opName) {
diff --git a/src/all_reduce.cu b/src/all_reduce.cu
index a38eabe057..4aa1feead7 100644
--- a/src/all_reduce.cu
+++ b/src/all_reduce.cu
@@ -7,7 +7,7 @@
 #include "cuda_runtime.h"
 #include "common.h"
 
-void AllReduceGetCollByteCount(size_t *sendcount, size_t *recvcount, size_t *paramcount, size_t *sendInplaceOffset, size_t *recvInplaceOffset, size_t count, int nranks) {
+void AllReduceGetCollByteCount(size_t *sendcount, size_t *recvcount, size_t *paramcount, size_t *sendInplaceOffset, size_t *recvInplaceOffset, size_t count, size_t eltSize, int nranks) {
   *sendcount = count;
   *recvcount = count;
   *sendInplaceOffset = 0;
@@ -55,7 +55,7 @@ struct testColl allReduceTest = {
 
 void AllReduceGetBuffSize(size_t *sendcount, size_t *recvcount, size_t count, int nranks) {
   size_t paramcount, sendInplaceOffset, recvInplaceOffset;
-  AllReduceGetCollByteCount(sendcount, recvcount, &paramcount, &sendInplaceOffset, &recvInplaceOffset, count, nranks);
+  AllReduceGetCollByteCount(sendcount, recvcount, &paramcount, &sendInplaceOffset, &recvInplaceOffset, count, /*eltSize=*/1, nranks);
 }
 
 testResult_t AllReduceRunTest(struct threadArgs* args, int root, ncclDataType_t type, const char* typeName, ncclRedOp_t op, const char* opName) {
diff --git a/src/alltoall.cu b/src/alltoall.cu
index 41c7c4ae33..dd085e54a9 100644
--- a/src/alltoall.cu
+++ b/src/alltoall.cu
@@ -7,12 +7,12 @@
 #include "cuda_runtime.h"
 #include "common.h"
 
-void AlltoAllGetCollByteCount(size_t *sendcount, size_t *recvcount, size_t *paramcount, size_t *sendInplaceOffset, size_t *recvInplaceOffset, size_t count, int nranks) {
-  *sendcount = (count/nranks)*nranks;
-  *recvcount = (count/nranks)*nranks;
+void AlltoAllGetCollByteCount(size_t *sendcount, size_t *recvcount, size_t *paramcount, size_t *sendInplaceOffset, size_t *recvInplaceOffset, size_t count, size_t eltSize, int nranks) {
+  *paramcount = (count/nranks) & -(16/eltSize);
+  *sendcount = nranks*(*paramcount);
+  *recvcount = *sendcount;
   *sendInplaceOffset = 0;
   *recvInplaceOffset = 0;
-  *paramcount = count/nranks;
 }
 
 testResult_t AlltoAllInitData(struct threadArgs* args, ncclDataType_t type, ncclRedOp_t op, int root, int rep, int in_place) {
@@ -74,7 +74,7 @@ struct testColl alltoAllTest = {
 
 void AlltoAllGetBuffSize(size_t *sendcount, size_t *recvcount, size_t count, int nranks) {
   size_t paramcount, sendInplaceOffset, recvInplaceOffset;
-  AlltoAllGetCollByteCount(sendcount, recvcount, &paramcount, &sendInplaceOffset, &recvInplaceOffset, count, nranks);
+  AlltoAllGetCollByteCount(sendcount, recvcount, &paramcount, &sendInplaceOffset, &recvInplaceOffset, count, /*eltSize=*/1, nranks);
 }
 
 testResult_t AlltoAllRunTest(struct threadArgs* args, int root, ncclDataType_t type, const char* typeName, ncclRedOp_t op, const char* opName) {
diff --git a/src/broadcast.cu b/src/broadcast.cu
index 903066a2b8..67e9af2f36 100644
--- a/src/broadcast.cu
+++ b/src/broadcast.cu
@@ -7,7 +7,7 @@
 #include "cuda_runtime.h"
 #include "common.h"
 
-void BroadcastGetCollByteCount(size_t *sendcount, size_t *recvcount, size_t *paramcount, size_t *sendInplaceOffset, size_t *recvInplaceOffset, size_t count, int nranks) {
+void BroadcastGetCollByteCount(size_t *sendcount, size_t *recvcount, size_t *paramcount, size_t *sendInplaceOffset, size_t *recvInplaceOffset, size_t count, size_t eltSize, int nranks) {
   *sendcount = count;
   *recvcount = count;
   *sendInplaceOffset = 0;
@@ -64,7 +64,7 @@ struct testColl broadcastTest = {
 
 void BroadcastGetBuffSize(size_t *sendcount, size_t *recvcount, size_t count, int nranks) {
   size_t paramcount, sendInplaceOffset, recvInplaceOffset;
-  BroadcastGetCollByteCount(sendcount, recvcount, &paramcount, &sendInplaceOffset, &recvInplaceOffset, count, nranks);
+  BroadcastGetCollByteCount(sendcount, recvcount, &paramcount, &sendInplaceOffset, &recvInplaceOffset, count, /*eltSize=*/1, nranks);
 }
 
 testResult_t BroadcastRunTest(struct threadArgs* args, int root, ncclDataType_t type, const char* typeName, ncclRedOp_t op, const char* opName) {
diff --git a/src/common.cu b/src/common.cu
index e1f8a85f16..6d103d797d 100644
--- a/src/common.cu
+++ b/src/common.cu
@@ -571,7 +571,7 @@ void setupArgs(size_t size, ncclDataType_t type, struct threadArgs* args) {
   size_t count, sendCount, recvCount, paramCount, sendInplaceOffset, recvInplaceOffset;
 
   count = size / wordSize(type);
-  args->collTest->getCollByteCount(&sendCount, &recvCount, &paramCount, &sendInplaceOffset, &recvInplaceOffset, (size_t)count, (size_t)nranks);
+  args->collTest->getCollByteCount(&sendCount, &recvCount, &paramCount, &sendInplaceOffset, &recvInplaceOffset, (size_t)count, wordSize(type), (size_t)nranks);
 
   args->nbytes = paramCount * wordSize(type);
   args->sendBytes = sendCount * wordSize(type);
diff --git a/src/common.h b/src/common.h
index e6762e1c97..478d7fb1c0 100644
--- a/src/common.h
+++ b/src/common.h
@@ -87,7 +87,7 @@ struct testColl {
   void (*getCollByteCount)(
       size_t *sendcount, size_t *recvcount, size_t *paramcount,
       size_t *sendInplaceOffset, size_t *recvInplaceOffset,
-      size_t count, int nranks);
+      size_t count, size_t eltSize, int nranks);
   testResult_t (*initData)(struct threadArgs* args, ncclDataType_t type,
       ncclRedOp_t op, int root, int rep, int in_place);
   void (*getBw)(size_t count, int typesize, double sec, double* algBw, double* busBw, int nranks);
diff --git a/src/gather.cu b/src/gather.cu
index 03ef4d9e3f..a4a7a30bcd 100644
--- a/src/gather.cu
+++ b/src/gather.cu
@@ -7,12 +7,12 @@
 #include "cuda_runtime.h"
 #include "common.h"
 
-void GatherGetCollByteCount(size_t *sendcount, size_t *recvcount, size_t *paramcount, size_t *sendInplaceOffset, size_t *recvInplaceOffset, size_t count, int nranks) {
-  *sendcount = count/nranks;
-  *recvcount = (count/nranks)*nranks;
-  *sendInplaceOffset = count/nranks;
+void GatherGetCollByteCount(size_t *sendcount, size_t *recvcount, size_t *paramcount, size_t *sendInplaceOffset, size_t *recvInplaceOffset, size_t count, size_t eltSize, int nranks) {
+  *sendcount = (count/nranks) & -(16/eltSize);
+  *recvcount = (*sendcount)*nranks;
+  *sendInplaceOffset = *sendcount;
   *recvInplaceOffset = 0;
-  *paramcount = count/nranks;
+  *paramcount = *sendcount;
 }
 
 testResult_t GatherInitData(struct threadArgs* args, ncclDataType_t type, ncclRedOp_t op, int root, int rep, int in_place) {
@@ -73,7 +73,7 @@ struct testColl gatherTest = {
 
 void GatherGetBuffSize(size_t *sendcount, size_t *recvcount, size_t count, int nranks) {
   size_t paramcount, sendInplaceOffset, recvInplaceOffset;
-  GatherGetCollByteCount(sendcount, recvcount, &paramcount, &sendInplaceOffset, &recvInplaceOffset, count, nranks);
+  GatherGetCollByteCount(sendcount, recvcount, &paramcount, &sendInplaceOffset, &recvInplaceOffset, count, /*eltSize=*/1, nranks);
 }
 
 testResult_t GatherRunTest(struct threadArgs* args, int root, ncclDataType_t type, const char* typeName, ncclRedOp_t op, const char* opName) {
diff --git a/src/hypercube.cu b/src/hypercube.cu
index 5c1456f8c7..b3459c91f4 100644
--- a/src/hypercube.cu
+++ b/src/hypercube.cu
@@ -9,8 +9,8 @@
 
 #define ALIGN 4
 
-void HyperCubeGetCollByteCount(size_t *sendcount, size_t *recvcount, size_t *paramcount, size_t *sendInplaceOffset, size_t *recvInplaceOffset, size_t count, int nranks) {
-  size_t base = (count/(ALIGN*nranks))*ALIGN;
+void HyperCubeGetCollByteCount(size_t *sendcount, size_t *recvcount, size_t *paramcount, size_t *sendInplaceOffset, size_t *recvInplaceOffset, size_t count, size_t eltSize, int nranks) {
+  size_t base = (count/nranks) & -(16/eltSize);
   *sendcount = base;
   *recvcount = base*nranks;
   *sendInplaceOffset = base;
@@ -78,7 +78,7 @@ struct testColl hyperCubeTest = {
 
 void HyperCubeGetBuffSize(size_t *sendcount, size_t *recvcount, size_t count, int nranks) {
   size_t paramcount, sendInplaceOffset, recvInplaceOffset;
-  HyperCubeGetCollByteCount(sendcount, recvcount, &paramcount, &sendInplaceOffset, &recvInplaceOffset, count, nranks);
+  HyperCubeGetCollByteCount(sendcount, recvcount, &paramcount, &sendInplaceOffset, &recvInplaceOffset, count, /*eltSize=*/1, nranks);
 }
 
 testResult_t HyperCubeRunTest(struct threadArgs* args, int root, ncclDataType_t type, const char* typeName, ncclRedOp_t op, const char* opName) {
diff --git a/src/reduce.cu b/src/reduce.cu
index f2fa80dd95..731abfa141 100644
--- a/src/reduce.cu
+++ b/src/reduce.cu
@@ -7,7 +7,7 @@
 #include "cuda_runtime.h"
 #include "common.h"
 
-void ReduceGetCollByteCount(size_t *sendcount, size_t *recvcount, size_t *paramcount, size_t *sendInplaceOffset, size_t *recvInplaceOffset, size_t count, int nranks) {
+void ReduceGetCollByteCount(size_t *sendcount, size_t *recvcount, size_t *paramcount, size_t *sendInplaceOffset, size_t *recvInplaceOffset, size_t count, size_t eltSize, int nranks) {
   *sendcount = count;
   *recvcount = count;
   *sendInplaceOffset = 0;
@@ -54,7 +54,7 @@ struct testColl reduceTest = {
 
 void ReduceGetBuffSize(size_t *sendcount, size_t *recvcount, size_t count, int nranks) {
   size_t paramcount, sendInplaceOffset, recvInplaceOffset;
-  ReduceGetCollByteCount(sendcount, recvcount, &paramcount, &sendInplaceOffset, &recvInplaceOffset, count, nranks);
+  ReduceGetCollByteCount(sendcount, recvcount, &paramcount, &sendInplaceOffset, &recvInplaceOffset, count, /*eltSize=*/1, nranks);
 }
 
 testResult_t ReduceRunTest(struct threadArgs* args, int root, ncclDataType_t type, const char* typeName, ncclRedOp_t op, const char* opName) {
diff --git a/src/reduce_scatter.cu b/src/reduce_scatter.cu
index ed372e3b9a..35cfdd4929 100644
--- a/src/reduce_scatter.cu
+++ b/src/reduce_scatter.cu
@@ -7,10 +7,8 @@
 #include "cuda_runtime.h"
 #include "common.h"
 
-#define ALIGN 4
-
-void ReduceScatterGetCollByteCount(size_t *sendcount, size_t *recvcount, size_t *paramcount, size_t *sendInplaceOffset, size_t *recvInplaceOffset, size_t count, int nranks) {
-  size_t base = (count/(ALIGN*nranks))*ALIGN;
+void ReduceScatterGetCollByteCount(size_t *sendcount, size_t *recvcount, size_t *paramcount, size_t *sendInplaceOffset, size_t *recvInplaceOffset, size_t count, size_t eltSize, int nranks) {
+  size_t base = (count/nranks) & -(16/eltSize);
   *sendcount = base*nranks;
   *recvcount = base;
   *sendInplaceOffset = 0;
@@ -59,7 +57,7 @@ struct testColl reduceScatterTest = {
 
 void ReduceScatterGetBuffSize(size_t *sendcount, size_t *recvcount, size_t count, int nranks) {
   size_t paramcount, sendInplaceOffset, recvInplaceOffset;
-  ReduceScatterGetCollByteCount(sendcount, recvcount, &paramcount, &sendInplaceOffset, &recvInplaceOffset, count, nranks);
+  ReduceScatterGetCollByteCount(sendcount, recvcount, &paramcount, &sendInplaceOffset, &recvInplaceOffset, count, /*eltSize=*/1, nranks);
 }
 
 testResult_t ReduceScatterRunTest(struct threadArgs* args, int root, ncclDataType_t type, const char* typeName, ncclRedOp_t op, const char* opName) {
diff --git a/src/scatter.cu b/src/scatter.cu
index 49d20e1601..d1eec71282 100644
--- a/src/scatter.cu
+++ b/src/scatter.cu
@@ -7,12 +7,12 @@
 #include "cuda_runtime.h"
 #include "common.h"
 
-void ScatterGetCollByteCount(size_t *sendcount, size_t *recvcount, size_t *paramcount, size_t *sendInplaceOffset, size_t *recvInplaceOffset, size_t count, int nranks) {
-  *sendcount = (count/nranks)*nranks;
-  *recvcount = count/nranks;
+void ScatterGetCollByteCount(size_t *sendcount, size_t *recvcount, size_t *paramcount, size_t *sendInplaceOffset, size_t *recvInplaceOffset, size_t count, size_t eltSize, int nranks) {
+  *recvcount = (count/nranks) & -(16/eltSize);
+  *sendcount = (*recvcount)*nranks;
   *sendInplaceOffset = 0;
-  *recvInplaceOffset = count/nranks;
-  *paramcount = count/nranks;
+  *recvInplaceOffset = *recvcount;
+  *paramcount = *recvcount;
 }
 
 testResult_t ScatterInitData(struct threadArgs* args, ncclDataType_t type, ncclRedOp_t op, int root, int rep, int in_place) {
@@ -69,7 +69,7 @@ struct testColl scatterTest = {
 
 void ScatterGetBuffSize(size_t *sendcount, size_t *recvcount, size_t count, int nranks) {
   size_t paramcount, sendInplaceOffset, recvInplaceOffset;
-  ScatterGetCollByteCount(sendcount, recvcount, &paramcount, &sendInplaceOffset, &recvInplaceOffset, count, nranks);
+  ScatterGetCollByteCount(sendcount, recvcount, &paramcount, &sendInplaceOffset, &recvInplaceOffset, count, /*eltSize=*/1, nranks);
 }
 
 testResult_t ScatterRunTest(struct threadArgs* args, int root, ncclDataType_t type, const char* typeName, ncclRedOp_t op, const char* opName) {
diff --git a/src/sendrecv.cu b/src/sendrecv.cu
index c9eb5bb427..67a4898b27 100644
--- a/src/sendrecv.cu
+++ b/src/sendrecv.cu
@@ -7,7 +7,7 @@
 #include "cuda_runtime.h"
 #include "common.h"
 
-void SendRecvGetCollByteCount(size_t *sendcount, size_t *recvcount, size_t *paramcount, size_t *sendInplaceOffset, size_t *recvInplaceOffset, size_t count, int nranks) {
+void SendRecvGetCollByteCount(size_t *sendcount, size_t *recvcount, size_t *paramcount, size_t *sendInplaceOffset, size_t *recvInplaceOffset, size_t count, size_t eltSize, int nranks) {
   *sendcount = count;
   *recvcount = count;
   *sendInplaceOffset = 0;
@@ -68,7 +68,7 @@ struct testColl sendRecvTest = {
 
 void SendRecvGetBuffSize(size_t *sendcount, size_t *recvcount, size_t count, int nranks) {
   size_t paramcount, sendInplaceOffset, recvInplaceOffset;
-  SendRecvGetCollByteCount(sendcount, recvcount, &paramcount, &sendInplaceOffset, &recvInplaceOffset, count, nranks);
+  SendRecvGetCollByteCount(sendcount, recvcount, &paramcount, &sendInplaceOffset, &recvInplaceOffset, count, /*eltSize=*/1, nranks);
 }
 
 testResult_t SendRecvRunTest(struct threadArgs* args, int root, ncclDataType_t type, const char* typeName, ncclRedOp_t op, const char* opName) {