diff --git a/RCTAppleHealthKit.xcodeproj/project.pbxproj b/RCTAppleHealthKit.xcodeproj/project.pbxproj
index d3ab2a5b767f905686242735639c588d22a0cdd1..6ef3d6e66ba402c1da4ba8191eec62e948bd6912 100644
--- a/RCTAppleHealthKit.xcodeproj/project.pbxproj
+++ b/RCTAppleHealthKit.xcodeproj/project.pbxproj
@@ -11,6 +11,7 @@
 		3774C8931D2092F20000B3F3 /* RCTAppleHealthKit.m in Sources */ = {isa = PBXBuildFile; fileRef = 3774C8921D2092F20000B3F3 /* RCTAppleHealthKit.m */; };
 		3774C89B1D2095450000B3F3 /* RCTAppleHealthKit+Queries.m in Sources */ = {isa = PBXBuildFile; fileRef = 3774C89A1D2095450000B3F3 /* RCTAppleHealthKit+Queries.m */; };
 		3774C89E1D2095850000B3F3 /* RCTAppleHealthKit+TypesAndPermissions.m in Sources */ = {isa = PBXBuildFile; fileRef = 3774C89D1D2095850000B3F3 /* RCTAppleHealthKit+TypesAndPermissions.m */; };
+		3774C8A11D20A6B90000B3F3 /* RCTAppleHealthKit+Utils.m in Sources */ = {isa = PBXBuildFile; fileRef = 3774C8A01D20A6B90000B3F3 /* RCTAppleHealthKit+Utils.m */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXCopyFilesBuildPhase section */
@@ -34,6 +35,8 @@
 		3774C89A1D2095450000B3F3 /* RCTAppleHealthKit+Queries.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = "RCTAppleHealthKit+Queries.m"; sourceTree = "<group>"; };
 		3774C89C1D2095850000B3F3 /* RCTAppleHealthKit+TypesAndPermissions.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = "RCTAppleHealthKit+TypesAndPermissions.h"; sourceTree = "<group>"; };
 		3774C89D1D2095850000B3F3 /* RCTAppleHealthKit+TypesAndPermissions.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = "RCTAppleHealthKit+TypesAndPermissions.m"; sourceTree = "<group>"; };
+		3774C89F1D20A6B90000B3F3 /* RCTAppleHealthKit+Utils.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = "RCTAppleHealthKit+Utils.h"; sourceTree = "<group>"; };
+		3774C8A01D20A6B90000B3F3 /* RCTAppleHealthKit+Utils.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = "RCTAppleHealthKit+Utils.m"; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
@@ -72,6 +75,8 @@
 				3774C89A1D2095450000B3F3 /* RCTAppleHealthKit+Queries.m */,
 				3774C89C1D2095850000B3F3 /* RCTAppleHealthKit+TypesAndPermissions.h */,
 				3774C89D1D2095850000B3F3 /* RCTAppleHealthKit+TypesAndPermissions.m */,
+				3774C89F1D20A6B90000B3F3 /* RCTAppleHealthKit+Utils.h */,
+				3774C8A01D20A6B90000B3F3 /* RCTAppleHealthKit+Utils.m */,
 			);
 			path = RCTAppleHealthKit;
 			sourceTree = "<group>";
@@ -133,6 +138,7 @@
 			buildActionMask = 2147483647;
 			files = (
 				3774C89B1D2095450000B3F3 /* RCTAppleHealthKit+Queries.m in Sources */,
+				3774C8A11D20A6B90000B3F3 /* RCTAppleHealthKit+Utils.m in Sources */,
 				3774C8931D2092F20000B3F3 /* RCTAppleHealthKit.m in Sources */,
 				3774C89E1D2095850000B3F3 /* RCTAppleHealthKit+TypesAndPermissions.m in Sources */,
 			);
diff --git a/RCTAppleHealthKit/RCTAppleHealthKit+Queries.h b/RCTAppleHealthKit/RCTAppleHealthKit+Queries.h
index 57769a414a1b9ab9ca05a1aaddaaca67fac2c87e..45139dffd11e5874818af91da77dbb3099e67743 100644
--- a/RCTAppleHealthKit/RCTAppleHealthKit+Queries.h
+++ b/RCTAppleHealthKit/RCTAppleHealthKit+Queries.h
@@ -12,6 +12,5 @@
 
 - (void)fetchMostRecentQuantitySampleOfType:(HKQuantityType *)quantityType predicate:(NSPredicate *)predicate completion:(void (^)(HKQuantity *mostRecentQuantity, NSError *error))completion;
 - (void)fetchSumOfSamplesTodayForType:(HKQuantityType *)quantityType unit:(HKUnit *)unit completion:(void (^)(double, NSError *))completionHandler;
-- (NSPredicate *)predicateForSamplesToday;
 
 @end
diff --git a/RCTAppleHealthKit/RCTAppleHealthKit+Queries.m b/RCTAppleHealthKit/RCTAppleHealthKit+Queries.m
index 3e34e6deac48b94b800c321e809fba9eb89082e5..2dba35bf169e21de6dbe48000295764462958a76 100644
--- a/RCTAppleHealthKit/RCTAppleHealthKit+Queries.m
+++ b/RCTAppleHealthKit/RCTAppleHealthKit+Queries.m
@@ -7,6 +7,7 @@
 //
 
 #import "RCTAppleHealthKit+Queries.h"
+#import "RCTAppleHealthKit+Utils.h"
 
 @implementation RCTAppleHealthKit (Queries)
 
@@ -35,14 +36,14 @@
                                                               completion(quantity, error);
                                                           }
                                                       }];
-    
+
     [self.healthStore executeQuery:query];
 }
 
 
 
 - (void)fetchSumOfSamplesTodayForType:(HKQuantityType *)quantityType unit:(HKUnit *)unit completion:(void (^)(double, NSError *))completionHandler {
-    NSPredicate *predicate = [self predicateForSamplesToday];
+    NSPredicate *predicate = [RCTAppleHealthKit predicateForSamplesToday];
     
     HKStatisticsQuery *query = [[HKStatisticsQuery alloc] initWithQuantityType:quantityType quantitySamplePredicate:predicate options:HKStatisticsOptionCumulativeSum completionHandler:^(HKStatisticsQuery *query, HKStatistics *result, NSError *error) {
         HKQuantity *sum = [result sumQuantity];
@@ -57,22 +58,4 @@
     [self.healthStore executeQuery:query];
 }
 
-
-
-
-#pragma mark - Convenience
-
-- (NSPredicate *)predicateForSamplesToday {
-    NSCalendar *calendar = [NSCalendar currentCalendar];
-    
-    NSDate *now = [NSDate date];
-    
-    NSDate *startDate = [calendar startOfDayForDate:now];
-    NSDate *endDate = [calendar dateByAddingUnit:NSCalendarUnitDay value:1 toDate:startDate options:0];
-    
-    return [HKQuery predicateForSamplesWithStartDate:startDate endDate:endDate options:HKQueryOptionStrictStartDate];
-}
-
-
-
 @end
diff --git a/RCTAppleHealthKit/RCTAppleHealthKit+Utils.h b/RCTAppleHealthKit/RCTAppleHealthKit+Utils.h
new file mode 100644
index 0000000000000000000000000000000000000000..08d547c273e2b153a1a3e589ad095b5e6a36216c
--- /dev/null
+++ b/RCTAppleHealthKit/RCTAppleHealthKit+Utils.h
@@ -0,0 +1,18 @@
+//
+//  RCTAppleHealthKit+Utils.h
+//  RCTAppleHealthKit
+//
+//  Created by Greg Wilson on 2016-06-26.
+//  Copyright © 2016 Greg Wilson. All rights reserved.
+//
+
+#import "RCTAppleHealthKit.h"
+
+@interface RCTAppleHealthKit (Utils)
+
++ (NSDate *)parseISO8601DateFromString:(NSString *)date;
++ (NSString *)buildISO8601StringFromDate:(NSDate *)date;
++ (NSPredicate *)predicateForSamplesToday;
++ (NSPredicate *)predicateForSamplesOnDay:(NSDate *)date;
++ (NSPredicate *)predicateForSamplesOnDayFromTimestamp:(NSString *)timestamp;
+@end
diff --git a/RCTAppleHealthKit/RCTAppleHealthKit+Utils.m b/RCTAppleHealthKit/RCTAppleHealthKit+Utils.m
new file mode 100644
index 0000000000000000000000000000000000000000..43c8cfb5f62ae06473f7025931b606d91afb0afa
--- /dev/null
+++ b/RCTAppleHealthKit/RCTAppleHealthKit+Utils.m
@@ -0,0 +1,50 @@
+//
+//  RCTAppleHealthKit+Utils.m
+//  RCTAppleHealthKit
+//
+//  Created by Greg Wilson on 2016-06-26.
+//  Copyright © 2016 Greg Wilson. All rights reserved.
+//
+
+#import "RCTAppleHealthKit+Utils.h"
+
+@implementation RCTAppleHealthKit (Utils)
+
+#pragma mark - Utilities
+
++ (NSDate *)parseISO8601DateFromString:(NSString *)date
+{
+    NSDateFormatter *dateFormatter = [NSDateFormatter new];
+    NSLocale *posix = [NSLocale localeWithLocaleIdentifier:@"en_US_POSIX"];
+    dateFormatter.locale = posix;
+    dateFormatter.dateFormat = @"yyyy-MM-dd'T'HH:mm:ssZZZZZ";
+    return [dateFormatter dateFromString:date];
+}
+
++ (NSString *)buildISO8601StringFromDate:(NSDate *)date
+{
+    NSDateFormatter *dateFormatter = [NSDateFormatter new];
+    NSLocale *posix = [NSLocale localeWithLocaleIdentifier:@"en_US_POSIX"];
+    dateFormatter.locale = posix;
+    dateFormatter.dateFormat = @"yyyy-MM-dd'T'HH:mm:ssZZZZZ";
+    return [dateFormatter stringFromDate:date];
+}
+
++ (NSPredicate *)predicateForSamplesToday {
+    NSDate *now = [NSDate date];
+    return [RCTAppleHealthKit predicateForSamplesOnDay:now];
+}
+
++ (NSPredicate *)predicateForSamplesOnDayFromTimestamp:(NSString *)timestamp {
+    NSDate *day = [RCTAppleHealthKit parseISO8601DateFromString:timestamp];
+    return [RCTAppleHealthKit predicateForSamplesOnDay:day];
+}
+
++ (NSPredicate *)predicateForSamplesOnDay:(NSDate *)date {
+    NSCalendar *calendar = [NSCalendar currentCalendar];
+    NSDate *startDate = [calendar startOfDayForDate:date];
+    NSDate *endDate = [calendar dateByAddingUnit:NSCalendarUnitDay value:1 toDate:startDate options:0];
+    return [HKQuery predicateForSamplesWithStartDate:startDate endDate:endDate options:HKQueryOptionStrictStartDate];
+}
+
+@end
diff --git a/RCTAppleHealthKit/RCTAppleHealthKit.m b/RCTAppleHealthKit/RCTAppleHealthKit.m
index abcd1cf7ed0d2a94377abbf8abf469cf15b95533..3a8969ca7f3229a0810bb16fb3c76ea52e1e658f 100644
--- a/RCTAppleHealthKit/RCTAppleHealthKit.m
+++ b/RCTAppleHealthKit/RCTAppleHealthKit.m
@@ -9,6 +9,7 @@
 #import "RCTAppleHealthKit.h"
 #import "RCTAppleHealthKit+Queries.h"
 #import "RCTAppleHealthKit+TypesAndPermissions.h"
+#import "RCTAppleHealthKit+Utils.h"
 
 @implementation RCTAppleHealthKit