diff --git a/docs/invoking.rst b/docs/invoking.rst
index b4473bccd..91e350fb2 100644
--- a/docs/invoking.rst
+++ b/docs/invoking.rst
@@ -130,7 +130,8 @@ the executable.
                  set server port to listen on/connect to to n (default 5201)
    
           -f, --format
-                 [kmgtKMGT]   format to report: Kbits/Mbits/Gbits/Tbits
+                 [kmgtKMGT]   format to report: kmgt for kbit/Mbit/Gbit/Tbit or KMGT for KiB/MiB/GiB/TiB
+
    
           -i, --interval n
                  pause n seconds between periodic throughput reports; default  is
diff --git a/src/iperf3.1 b/src/iperf3.1
index 0937fd16d..859ec5d5b 100644
--- a/src/iperf3.1
+++ b/src/iperf3.1
@@ -111,7 +111,7 @@ viewed by running iperf3 with the -h flag.
 set server port to listen on/connect to to \fIn\fR (default 5201)
 .TP
 .BR -f ", " --format " "
-[kmgtKMGT]   format to report: Kbits/Mbits/Gbits/Tbits
+[kmgtKMGT]   format to report: kmgt for kbit/Mbit/Gbit/Tbit or KMGT for KiB/MiB/GiB/TiB
 .TP
 .BR -i ", " --interval " \fIn\fR"
 pause \fIn\fR seconds between periodic throughput reports;
diff --git a/src/iperf_locale.c b/src/iperf_locale.c
index 58a6d77f8..188a80f2e 100644
--- a/src/iperf_locale.c
+++ b/src/iperf_locale.c
@@ -98,7 +98,7 @@ const char usage_longstr[] = "Usage: iperf3 [-s|-c host] [options]\n"
                            "       iperf3 [-h|--help] [-v|--version]\n\n"
                            "Server or Client:\n"
                            "  -p, --port      #         server port to listen on/connect to\n"
-                           "  -f, --format   [kmgtKMGT] format to report: Kbits, Mbits, Gbits, Tbits\n"
+                           "  -f, --format   [kmgtKMGT] format to report: kmgt for kbit/Mbit/Gbit/Tbit or KMGT for KiB/MiB/GiB/TiB\n"
                            "  -i, --interval  #         seconds between periodic throughput reports\n"
                            "  -I, --pidfile file        write PID file\n"
                            "  -F, --file name           xmit/recv the specified file\n"
diff --git a/src/t_units.c b/src/t_units.c
index 73f21a9d8..f40bfc718 100644
--- a/src/t_units.c
+++ b/src/t_units.c
@@ -74,34 +74,34 @@ main(int argc, char **argv)
     assert(llu == unit_atoi("3t"));
 
     unit_snprintf(s, 11, 1024.0, 'A');
-    assert(strncmp(s, "1.00 KByte", 11) == 0);
+    assert(strncmp(s, "1.00 KiB", 11) == 0);
 
     unit_snprintf(s, 11, 1024.0 * 1024.0, 'A');
-    assert(strncmp(s, "1.00 MByte", 11) == 0);
+    assert(strncmp(s, "1.00 MiB", 11) == 0);
 
     unit_snprintf(s, 11, 1000.0, 'k');
-    assert(strncmp(s, "8.00 Kbit", 11) == 0);
+    assert(strncmp(s, "8.00 kbit", 11) == 0);
 
     unit_snprintf(s, 11, 1000.0 * 1000.0, 'a');
     assert(strncmp(s, "8.00 Mbit", 11) == 0);
 
     d = 4.0 * 1024 * 1024 * 1024;
     unit_snprintf(s, 11, d, 'A');
-    assert(strncmp(s, "4.00 GByte", 11) == 0);
+    assert(strncmp(s, "4.00 GiB", 11) == 0);
 
     unit_snprintf(s, 11, d, 'a');
     assert(strncmp(s, "34.4 Gbit", 11) == 0);
 
     d = 4.0 * 1024 * 1024 * 1024 * 1024;
     unit_snprintf(s, 11, d, 'A');
-    assert(strncmp(s, "4.00 TByte", 11) == 0);
+    assert(strncmp(s, "4.00 TiB", 11) == 0);
 
     unit_snprintf(s, 11, d, 'a');
     assert(strncmp(s, "35.2 Tbit", 11) == 0);
 
     d = 4.0 * 1024 * 1024 * 1024 * 1024 * 1024;
     unit_snprintf(s, 11, d, 'A');
-    assert(strncmp(s, "4096 TByte", 11) == 0);
+    assert(strncmp(s, "4096 TiB", 11) == 0);
 
     unit_snprintf(s, 11, d, 'a');
     assert(strncmp(s, "36029 Tbit", 11) == 0);
diff --git a/src/units.c b/src/units.c
index 7376a0b7f..bc6679b33 100644
--- a/src/units.c
+++ b/src/units.c
@@ -237,17 +237,17 @@ extern    "C"
     const char *label_byte[] =
     {
 	"Byte",
-	"KByte",
-	"MByte",
-	"GByte",
-	"TByte"
+	"KiB",
+	"MiB",
+	"GiB",
+	"TiB"
     };
 
 /* labels for bit formats [kmgt] */
     const char *label_bit[] =
     {
 	"bit",
-	"Kbit",
+	"kbit",
 	"Mbit",
 	"Gbit",
 	"Tbit"
@@ -258,8 +258,8 @@ extern    "C"
  *
  * Given a number in bytes and a format, converts the number and
  * prints it out with a bits or bytes label.
- *   B, K, M, G, A for Byte, Kbyte, Mbyte, Gbyte, adaptive byte
- *   b, k, m, g, a for bit,  Kbit,  Mbit,  Gbit,  adaptive bit
+ *   B, K, M, G, A for Byte, KiB, MiB, GiB, adaptive byte
+ *   b, k, m, g, a for bit,  kbit, Mbit , Gbit,  adaptive bit
  * adaptive picks the "best" one based on the number.
  * s should be at least 11 chars long
  * (4 digits + space + 5 chars max + null)