diff --git a/rest_framework/throttling.py b/rest_framework/throttling.py
index 37e71e93e..c0a9ed6fc 100644
--- a/rest_framework/throttling.py
+++ b/rest_framework/throttling.py
@@ -2,6 +2,7 @@
 Provides various throttling policies.
 """
 import time
+import re
 
 from django.core.cache import cache as default_cache
 from django.core.exceptions import ImproperlyConfigured
@@ -9,6 +10,7 @@ from django.core.exceptions import ImproperlyConfigured
 from rest_framework.settings import api_settings
 
 
+
 class BaseThrottle:
     """
     Rate throttling of requests.
@@ -66,6 +68,7 @@ class SimpleRateThrottle(BaseThrottle):
     cache_format = 'throttle_%(scope)s_%(ident)s'
     scope = None
     THROTTLE_RATES = api_settings.DEFAULT_THROTTLE_RATES
+    _RATE_DENOMINATOR_REGEX= re.compile("^(\d*)(\D+)$")
 
     def __init__(self):
         if not getattr(self, 'rate', None):
@@ -105,10 +108,16 @@ class SimpleRateThrottle(BaseThrottle):
             return (None, None)
         num, period = rate.split('/')
         num_requests = int(num)
-        denominator_num = period[:-1]
-        denominator_num = int(denominator_num) if len(denominator_num) > 0 else 1
-        duration = {'s': 1, 'm': 60, 'h': 3600, 'd': 86400}[period[-1]]
-        duration *= denominator_num
+        
+        denominator = period[:-1]
+        m = re.search(self._RATE_DENOMINATOR_REGEX, denominator)
+        dg = m.groups()
+
+        dn= int(m[0]) if len(m[0])>0 else 1
+        du = m[1][0]
+
+        duration = {'s': 1, 'm': 60, 'h': 3600, 'd': 86400}[du]
+        duration *= dn
         return (num_requests, duration)
 
     def allow_request(self, request, view):