diff --git a/voussoirkit/kbps.py b/voussoirkit/kbps.py
new file mode 100644
index 0000000..16caa4f
--- /dev/null
+++ b/voussoirkit/kbps.py
@@ -0,0 +1,63 @@
+'''
+Find time, filesize, or bitrate, given two of the three.
+
+For example:
+
+kbps.py --time 1:00:00 --size 2g
+kbps.py --time 1:00:00 --kbps 4660
+kbps.py --size 2g --kpbps 4660
+'''
+import argparse
+import sys
+
+from voussoirkit import bytestring
+from voussoirkit import hms
+
+def kbps(time=None, size=None, kbps=None):
+    if [time, size, kbps].count(None) != 1:
+        raise ValueError('Incorrect number of unknowns.')
+
+    if time is None:
+        kilobits = size / 128
+        time = kilobits / kbps
+        return time
+
+    if size is None:
+        kibs = kbps / 8
+        size = kibs * 1024
+        size *= time
+        return size
+
+    if kbps is None:
+        kibs = size / 1024
+        kilobits = kibs * 8
+        kbps = kilobits / time
+        return kbps
+
+def kbps_argparse(args):
+    time = args.time and hms.hms_to_seconds(args.time)
+    size = args.size and bytestring.parsebytes(args.size)
+    kibs = args.kbps and int(args.kbps)
+
+    result = kbps(time=time, size=size, kbps=kibs)
+
+    if time is None:
+        print(hms.seconds_to_hms(time))
+    if size is None:
+        print(bytestring.bytestring(size))
+    if kibs is None:
+        print('%d kbps' % round(result))
+
+def main(argv):
+    parser = argparse.ArgumentParser()
+
+    parser.add_argument('-t', '--time', dest='time', default=None)
+    parser.add_argument('-s', '--size', dest='size', default=None)
+    parser.add_argument('-k', '--kbps', dest='kbps', default=None)
+    parser.set_defaults(func=kbps_argparse)
+
+    args = parser.parse_args(argv)
+    return args.func(args)
+
+if __name__ == '__main__':
+    raise SystemExit(main(sys.argv[1:]))