Hanke–Henry Permanent Calendar

Under the Hanke–Henry Permanent Calendar January, February, April, May, July, August, October, and November have thirty days, while March, June, September, and December have thirty-one so that each quarter contains two 30-day months followed by one month of 31 days (30:30:31).

While the Hanke–Henry Permanent Calendar changes the length of the months, the week and days remain the same.

[5] Hanke and Henry do not offer a serious discussion of anniversaries, especially the ones commemorated on 31 January, 31 May, 31 July, 31 August, and 31 October (as these days are eliminated).

Henry argues that his proposal will succeed where some others have failed because it keeps the weekly cycle intact, and therefore respects the Fourth Commandment (Remember the sabbath day, to keep it holy)[6] of Judaism and Christianity.

Henry's original version had essentially the same structure given above, but inserted its leap week named "Newton" between June and July in the middle of the year.

The target date for universal adoption was 1 January 2017 then, but was postponed to 2018,[8] when the calendar design was changed in early 2016 to adopt Monday as the start of the week, quarter and year, to better comply with existing international standard ISO 8601.

The key difference between Robert McClenon's calendar proposal and Henry's modification is that the former has a simple rule for determining which years have a leap week.