diff --git a/Makefile b/Makefile
index 884c31f..a008e1b 100644
--- a/Makefile
+++ b/Makefile
@@ -25,7 +25,7 @@ endif
 CHEAT_ARG := $(shell ./update-git-hash-if-necessary)
 
 PROGRAMS = navparse ubxtool navnexus navcat navrecv navdump testrunner navdisplay tlecatch reporter sp3feed \
-	galmonmon rinreport rtcmtool
+	galmonmon rinreport rtcmtool gndate
 
 all: navmon.pb.cc $(PROGRAMS)
 
@@ -127,5 +127,9 @@ ubxtool: navmon.pb.o ubxtool.o ubx.o bits.o ext/fmt-6.1.2/src/format.o galileo.o
 testrunner: navmon.pb.o testrunner.o ubx.o bits.o ext/fmt-6.1.2/src/format.o galileo.o  gps.o beidou.o ephemeris.o sp3.o osen.o navmon.o rinex.o githash.o
 	$(CXX) -std=gnu++17 $^ -o $@ -L/usr/local/lib -lprotobuf -lz 
 
+gndate: gndate.o githash.o ext/fmt-6.1.2/src/format.o navmon.o
+	$(CXX) -std=gnu++17 $^ -o $@ -L/usr/local/lib
+	
+
 check: testrunner
 	./testrunner
diff --git a/gndate.cc b/gndate.cc
new file mode 100644
index 0000000..d027981
--- /dev/null
+++ b/gndate.cc
@@ -0,0 +1,57 @@
+#include "navmon.hh"
+#include <iostream>
+#include "CLI/CLI.hpp"
+#include "version.hh"
+
+extern const char* g_gitHash;
+using namespace std;
+
+int main(int argc, char** argv)
+{
+  string program("gndate");
+  CLI::App app(program);
+  string date;
+  bool doGPSWN{false}, doGALWN{false}, doVERSION{false}, doUTC{false};
+  app.add_flag("--version", doVERSION, "show program version and copyright");
+  app.add_option("--date,-d", date, "yyyy-mm-dd hh:mm");
+  app.add_flag("--utc,-u", doUTC, "Interpret --date,-d as UTC");
+  app.add_flag("--gps-wn", doGPSWN, "Print GPS week number");
+  app.add_flag("--gal-wn", doGALWN, "Print GPS week number");
+  try {
+    app.parse(argc, argv);
+  } catch(const CLI::Error &e) {
+    return app.exit(e);
+  }
+
+  if(doVERSION) {
+    showVersion(program.c_str(), g_gitHash);
+    exit(0);
+  }
+
+  
+  time_t now;
+  if(date.empty())
+    now = time(0);
+  else {
+    if(doUTC)
+      setenv("TZ", "UTC", 1);
+    now = parseTime(date);
+  }
+  
+  int wn, tow;
+
+  if(doGPSWN) {
+    getGPSDateFromUTC(now, wn, tow);
+    cout<<wn<<endl;
+  }
+  else if(doGALWN) {
+    getGalDateFromUTC(now, wn, tow);
+    cout<<wn<<endl;
+  }
+  else {
+    getGPSDateFromUTC(now, wn, tow);
+    cout<<"GPS Week Number (non-wrapped): "<< wn << ", tow " << tow << endl;
+    getGalDateFromUTC(now, wn, tow);
+    cout<<"Galileo Week Number: "<< wn << ", tow " << tow << endl;
+  }
+}