## The Equation of Time:

Values presented are averages and may be in error by 10-15 seconds in January and December of certain years.

The apparent motion of the Sun along the plane of the ecliptic is not regular. This non-uniform motion is caused by two things: 1)The Earth's orbit is not circular but elliptical and 2) the Earth's axis is tilted about 23 degrees from the ecliptic. Mean Solar time assumes that the orbit is circular that there is no tilt and everything is like "clockwork". However this is not the case, so a Sundial (which shows Real Solar time) differs from the Mean time by the Equation of Time. Since clocks and watches use Mean Solar Time there will be an apparent error between the time your watch reads and the time your dial reads.

Day JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
1 -3:12 -13:33 -12:34 -4:08 +2:51 +2:25 -3:33 -6:16 -0:12 +10:05 +16:20 +11:11
2 -3:40 -13:41 -12:23 -3:50 +2:59 +2:16 -3:45 -6:13 +0:07 +10:24 +16:22 +10:49
3 -4:08 -13:48 -12:11 -3:32 +3:06 +2:06 -3:57 -6:09 +0:26 +10:43 +16:23 +10:26
4 -4:36 -13:55 -11:58 -3:14 +3:12 +1:56 -4:08 -6:04 -0:45 +11:02 +16:23 +10:02
5 -5:03 -14:01 -11:45 -2:57 +3:18 +1:46 -4:19 -5:59 -1:05 +11:20 +16:22 +9:38
6 -5:30 -14:06 -11:31 -2:40 +3:23 +1:36 -4:29 -5:53 +1:25 +11:38 +16:20 +9:13
7 -5:57 -14:10 -11:17 -2:23 +3:27 +1:25 -4:39 -5:46 +1:45 +11:56 +16:18 +8:48
8 -6:23 -14:14 -11:03 -2:06 +3:31 +1:14 -4:49 -5:39 +2:05 +12:13 +16:15 +8:22
9 -6:49 -14:16 -10:48 -1:49 +3:35 +1:03 -4:58 -5:31 +2:26 +12:30 +16:11 +7:56
10 -7:14 -14:18 -10:33 -1:32 +3:38 +0:51 -5:07 -5:23 +2:47 +12:46 +16:06 +7:29
11 -7:38 -14:19 -10:18 -1:16 +3:40 +0:39 -5:16 -5:14 +3:08 +13:02 +16:00 +7:02
12 -8:02 -14:20 -10:02 -1:00 +3:42 +0:27 -5:24 -5:05 +3:29 +13:18 +15:53 +6:34
13 -8:25 -14:19 -9:46 -0:44 +3:44 +0:15 -5:32 -4:55 +3:50 +13:33 +15:46 +6:06
14 -8:48 -14:18 -9:30 -0:29 +3:44 +0:03 -5:39 -4:44 +4:11 +13:47 +15:37 +5:38
15 -9:10 -14:16 -9:13 -0:14 +3:44 -0:10 -5:46 -4:33 +4:32 +14:01 +15:28 +5:09
16 -9:32 -14:13 -8:56 +0:01 +3:44 -0:23 -5:52 -4:21 +4:53 +14:14 +15:18 +4:40
17 -9:52 -14:10 -8:39 +0:15 +3:43 -0:36 -5:58 -4:09 +5:14 14:27 +15:07 +4:11
18 -10:12 -14:06 -8:22 +0:29 +3:41 -0:49 -6:03 -3:57 +5:35 +14:39 +14:56 +3:42
19 -10:32 -14:01 -8:04 +0:43 +3:39 -1:02 -6:08 -3:44 +5:56 +14:51 +14:43 +3:13
20 -10:50 -13:55 -7:46 +0:56 +3:37 -1:15 -6:12 -3:30 +6:18 +15:02 +14:30 +2:43
21 -11:08 -13:49 -7:28 +1:00 +3:34 -1:28 -6:15 -3:16 +6:40 +15:12 +14:16 +2:13
22 -11:25 -13:42 -7:10 +1:21 +3:30 -1:41 -6:18 -3:01 +7:01 +15:22 +14:01 +1:43
23 -11:41 -13:35 -6:52 +1:33 +3:24 -1:54 -6:20 -2:46 +7:22 +15:31 +13:45 +1:13
24 -11:57 -13:27 -6:34 +1:45 +3:21 -2:07 -6:22 -2:30 +7:43 +15:40 +13:28 +0:43
25 -12:12 -13:18 -6:16 +1:56 +3:16 -2:20 -6:24 -2:14 +8:04 +15:47 +13:11 +0:13
26 -12:26 -13:09 -5:58 +2:06 +3:10 -2:33 -6:25 -1:58 +8:25 +15:54 +12:53 -0:17
27 -12:39 -12:59 -5:40 +2:16 +3:03 -2:45 -6:25 -1:41 +8:46 +16:01 +12:34 -0:47
28 -12:51 -12:48 -5:21 +2:26 +2:56 -2:57 -6:24 -1:24 +9:06 +16:06 +12:14 -1:16
29 -13:03 -12:42 -5:02 +2:35 +2:49 -3:09 -6:23 -1:07 +9:26 +16:11 +11:54 -1:45
30 -13:14 -4:44 +2:43 +2:41 -3:21 -6:21 -0:49 +9:46 +16:15 +11:33 -2:14
31 -13:24 -4:26 +2:33 -6:19 -0:31 +16:18 -2:43
Day JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Format of data is: [(+/-) minutes:seconds] where + is fast and - is slow.

The equation of time data is usually represented graphically for ease in use. Below is a graph of the data from the table above.