A few SF writers have amused themselves by having their far-future space-faring characters abandon our “months” and “years”, and do everything in days or hours. This makes a certain sense when you get away from Earth; the daily rhythm is the one most deeply built into us, and we probably will keep something like 24-hour days on ships. And we’ll certainly keep the “second”, if it’s really “us” spreading out to the stars, because it’s basic to all our science and engineering; and completely arbitrary, so it’s as good as anything else.
I’ve wanted a table of time conversions for decoding such stories for some time, and finally wrote a Perl script to create one. So, for amusement, reference, and so forth, here they are.
The actual difficulty is primarily deciding how to format them. I don’t think this is optimal yet, but it’s much better than some things I tried.
The “year” length is the official solar year. All calculations are done from seconds.
The first set of tables are powers of 10 in one of the units.
Seconds   Minutes     Hours      Days     Weeks     Years 1e+03      16.7     0.278    0.0116   0.00165  3.17e-05 1e+04       167      2.78     0.116    0.0165  0.000317 1e+05  1.67e+03      27.8      1.16     0.165   0.00317 1e+06  1.67e+04       278      11.6      1.65    0.0317 1e+07  1.67e+05  2.78e+03       116      16.5     0.317 1e+08  1.67e+06  2.78e+04  1.16e+03       165      3.17 1e+09  1.67e+07  2.78e+05  1.16e+04  1.65e+03      31.7 1e+10  1.67e+08  2.78e+06  1.16e+05  1.65e+04       317 1e+11  1.67e+09  2.78e+07  1.16e+06  1.65e+05  3.17e+03 1e+12  1.67e+10  2.78e+08  1.16e+07  1.65e+06  3.17e+04 1e+13  1.67e+11  2.78e+09  1.16e+08  1.65e+07  3.17e+05 1e+14  1.67e+12  2.78e+10  1.16e+09  1.65e+08  3.17e+06 Seconds   Minutes     Hours      Days     Weeks     Years 6e+04     1e+03      16.7     0.694    0.0992    0.0019 6e+05     1e+04       167      6.94     0.992     0.019 6e+06     1e+05  1.67e+03      69.4      9.92      0.19 6e+07     1e+06  1.67e+04       694      99.2       1.9 6e+08     1e+07  1.67e+05  6.94e+03       992        19 6e+09     1e+08  1.67e+06  6.94e+04  9.92e+03       190 6e+10     1e+09  1.67e+07  6.94e+05  9.92e+04   1.9e+03 6e+11     1e+10  1.67e+08  6.94e+06  9.92e+05   1.9e+04 6e+12     1e+11  1.67e+09  6.94e+07  9.92e+06   1.9e+05 Seconds   Minutes     Hours      Days     Weeks     Years 3.6e+03        60         1    0.0417   0.00595  0.000114 3.6e+04       600        10     0.417    0.0595   0.00114 3.6e+05     6e+03       100      4.17     0.595    0.0114 3.6e+06     6e+04     1e+03      41.7      5.95     0.114 3.6e+07     6e+05     1e+04       417      59.5      1.14 3.6e+08     6e+06     1e+05  4.17e+03       595      11.4 3.6e+09     6e+07     1e+06  4.17e+04  5.95e+03       114 3.6e+10     6e+08     1e+07  4.17e+05  5.95e+04  1.14e+03 3.6e+11     6e+09     1e+08  4.17e+06  5.95e+05  1.14e+04 3.6e+12     6e+10     1e+09  4.17e+07  5.95e+06  1.14e+05 3.6e+13     6e+11     1e+10  4.17e+08  5.95e+07  1.14e+06 Seconds   Minutes     Hours      Days     Weeks     Years 8.64e+04  1.44e+03        24         1     0.143   0.00274 8.64e+05  1.44e+04       240        10      1.43    0.0274 8.64e+06  1.44e+05   2.4e+03       100      14.3     0.274 8.64e+07  1.44e+06   2.4e+04     1e+03       143      2.74 8.64e+08  1.44e+07   2.4e+05     1e+04  1.43e+03      27.4 8.64e+09  1.44e+08   2.4e+06     1e+05  1.43e+04       274 8.64e+10  1.44e+09   2.4e+07     1e+06  1.43e+05  2.74e+03 8.64e+11  1.44e+10   2.4e+08     1e+07  1.43e+06  2.74e+04 8.64e+12  1.44e+11   2.4e+09     1e+08  1.43e+07  2.74e+05 8.64e+13  1.44e+12   2.4e+10     1e+09  1.43e+08  2.74e+06 Seconds   Minutes     Hours      Days     Weeks     Years 3.16e+07  5.26e+05  8.77e+03       365      52.2         1 3.16e+08  5.26e+06  8.77e+04  3.65e+03       522        10 3.16e+09  5.26e+07  8.77e+05  3.65e+04  5.22e+03       100 3.16e+10  5.26e+08  8.77e+06  3.65e+05  5.22e+04     1e+03 3.16e+11  5.26e+09  8.77e+07  3.65e+06  5.22e+05     1e+04 3.16e+12  5.26e+10  8.77e+08  3.65e+07  5.22e+06     1e+05 3.16e+13  5.26e+11  8.77e+09  3.65e+08  5.22e+07     1e+06
Or, in a variant presentation, sorted by actual length of each period:
Seconds   Minutes     Hours      Days     Weeks     Years 1e+03      16.7     0.278    0.0116   0.00165  3.17e-05 3.6e+03        60         1    0.0417   0.00595  0.000114 1e+04       167      2.78     0.116    0.0165  0.000317 3.6e+04       600        10     0.417    0.0595   0.00114 6e+04     1e+03      16.7     0.694    0.0992    0.0019 8.64e+04  1.44e+03        24         1     0.143   0.00274 1e+05  1.67e+03      27.8      1.16     0.165   0.00317 3.6e+05     6e+03       100      4.17     0.595    0.0114 6e+05     1e+04       167      6.94     0.992     0.019 8.64e+05  1.44e+04       240        10      1.43    0.0274 1e+06  1.67e+04       278      11.6      1.65    0.0317 3.6e+06     6e+04     1e+03      41.7      5.95     0.114 6e+06     1e+05  1.67e+03      69.4      9.92      0.19 8.64e+06  1.44e+05   2.4e+03       100      14.3     0.274 1e+07  1.67e+05  2.78e+03       116      16.5     0.317 3.16e+07  5.26e+05  8.77e+03       365      52.2         1 3.6e+07     6e+05     1e+04       417      59.5      1.14 6e+07     1e+06  1.67e+04       694      99.2       1.9 8.64e+07  1.44e+06   2.4e+04     1e+03       143      2.74 1e+08  1.67e+06  2.78e+04  1.16e+03       165      3.17 3.16e+08  5.26e+06  8.77e+04  3.65e+03       522        10 3.6e+08     6e+06     1e+05  4.17e+03       595      11.4 6e+08     1e+07  1.67e+05  6.94e+03       992        19 8.64e+08  1.44e+07   2.4e+05     1e+04  1.43e+03      27.4 1e+09  1.67e+07  2.78e+05  1.16e+04  1.65e+03      31.7 3.16e+09  5.26e+07  8.77e+05  3.65e+04  5.22e+03       100 3.6e+09     6e+07     1e+06  4.17e+04  5.95e+03       114 6e+09     1e+08  1.67e+06  6.94e+04  9.92e+03       190 8.64e+09  1.44e+08   2.4e+06     1e+05  1.43e+04       274 1e+10  1.67e+08  2.78e+06  1.16e+05  1.65e+04       317 3.16e+10  5.26e+08  8.77e+06  3.65e+05  5.22e+04     1e+03 3.6e+10     6e+08     1e+07  4.17e+05  5.95e+04  1.14e+03 6e+10     1e+09  1.67e+07  6.94e+05  9.92e+04   1.9e+03 8.64e+10  1.44e+09   2.4e+07     1e+06  1.43e+05  2.74e+03 1e+11  1.67e+09  2.78e+07  1.16e+06  1.65e+05  3.17e+03 3.16e+11  5.26e+09  8.77e+07  3.65e+06  5.22e+05     1e+04 3.6e+11     6e+09     1e+08  4.17e+06  5.95e+05  1.14e+04 6e+11     1e+10  1.67e+08  6.94e+06  9.92e+05   1.9e+04 8.64e+11  1.44e+10   2.4e+08     1e+07  1.43e+06  2.74e+04 1e+12  1.67e+10  2.78e+08  1.16e+07  1.65e+06  3.17e+04 3.16e+12  5.26e+10  8.77e+08  3.65e+07  5.22e+06     1e+05 3.6e+12     6e+10     1e+09  4.17e+07  5.95e+06  1.14e+05 6e+12     1e+11  1.67e+09  6.94e+07  9.92e+06   1.9e+05 8.64e+12  1.44e+11   2.4e+09     1e+08  1.43e+07  2.74e+05 1e+13  1.67e+11  2.78e+09  1.16e+08  1.65e+07  3.17e+05 3.16e+13  5.26e+11  8.77e+09  3.65e+08  5.22e+07     1e+06 3.6e+13     6e+11     1e+10  4.17e+08  5.95e+07  1.14e+06 8.64e+13  1.44e+12   2.4e+10     1e+09  1.43e+08  2.74e+06 1e+14  1.67e+12  2.78e+10  1.16e+09  1.65e+08  3.17e+06
You may download a zip file containing the script.