A1_format_calendar.tex

% DIN-A4 doublesided year calendar
% Author: Robert Krause
% Modified by: Sérgio Jardim (@sjardim)
% License : Creative Commons attribution license
% Submitted to TeXample.net on 13 July 2012
\documentclass[landscape,a1paper,21pt]{scrartcl}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{tikz} 			% Use the calendar.sty style

\usepackage{fancyhdr}		% header and footer
\usepackage{fix-cm}		% Large year in header

\usepackage[landscape, headheight = 1cm, margin=0cm,
  top = 1.2cm, nofoot]{geometry}
\usetikzlibrary{calc}
\usetikzlibrary{calendar}

\usepackage{verbatim}


\usepackage{PTSansNarrow}
\renewcommand*\familydefault{\sfdefault}

%========= INSTRUCTIONS ============================================

% TO EDIT THE CALENDAR, FOLLOW THE #NUMBERED STEPS (ONLY 3)
% IGNORE THE OTHER SETTINGS UNLESS YOU KNOW WHAT YOU'RE DOING :)
% LINES 32, 55 AND 87

% #01 Set the base year
\def\year{2018}
\def\nextYear{2019}


% Names of Holidays are inserted by employing this macro
\def\holiday#1#2{
  \node [anchor=north west, text width= 5.9cm] at
    ($(cal-#1.north west)+(0em, 0em)$) {\tiny{#2}};
}

%Header
\renewcommand{\headrulewidth}{0.0pt}
\setlength{\headheight}{10ex}
%\chead{}
%Footer
\cfoot{\footnotesize\texttt{}}

\definecolor{titlescolor}{RGB}{128,128,128}

\begin{document}
\pagestyle{fancy}
\begin{center}
\begin{tikzpicture}[every day/.style={anchor = north}]

\calendar[
% #02 Set the months period (that will appear as columns)
  dates=\year-01-01 to \nextYear-01-31,
  name=cal,
  day yshift = 1em,
  day code=
  {
    \node[name=\pgfcalendarsuggestedname,every day,shape=rectangle,
    minimum height= 1.7cm, text width = 5.9cm, draw = black]{\hskip-.15cm\bfseries\tikzdaytext};
    \draw (-9ex, -1.4ex) node[anchor = west]{\tiny%
      \pgfcalendarweekdayshortname{\pgfcalendarcurrentweekday}};
  },
  execute before day scope=
  {
    \ifdate{day of month=1}
    {
      % Shift right
      \pgftransformxshift{6.4cm}
      % Print month name 
      \draw (0,-.2ex)node [shape=rectangle, minimum height= 1cm,
        text width = 5.9cm, fill = titlescolor, text= white, draw = titlescolor, text centered]
        {\MakeUppercase{\large\textbf{\pgfcalendarmonthname{\pgfcalendarcurrentmonth}\strut}}};
    }{}
    \ifdate{workday}
    {
      % normal days are white
      \tikzset{every day/.style={fill=none}}      
    }{}
    % Saturdays
    \ifdate{Saturday}{\tikzset{every day/.style={fill=black!15}}}{}
    % Sundays
    \ifdate{Sunday}{\tikzset{every day/.style={fill=black!30}}}{}
    % Holidays
    % #03 Set the holidays, per line            
    \ifdate{equals=\year-01-01}{\tikzset{every day/.style={fill=orange!40}}}{} % New Year's Eve    
    \ifdate{equals=\year-01-16}{\tikzset{every day/.style={fill=orange!40}}}{} % Martin L. King day
    \ifdate{equals=\year-02-20}{\tikzset{every day/.style={fill=orange!40}}}{} % President's day
    \ifdate{equals=\year-05-29}{\tikzset{every day/.style={fill=orange!40}}}{} % Memorial Day
    \ifdate{equals=\year-07-04}{\tikzset{every day/.style={fill=orange!40}}}{} % Independence Day
    \ifdate{equals=\year-09-04}{\tikzset{every day/.style={fill=orange!40}}}{} % Labor day
    \ifdate{equals=\year-10-09}{\tikzset{every day/.style={fill=orange!40}}}{} % Columbus day    
    \ifdate{equals=\year-11-11}{\tikzset{every day/.style={fill=orange!40}}}{} % Veterans day
    \ifdate{equals=\year-11-23}{\tikzset{every day/.style={fill=orange!40}}}{} % Thanksgiving day
    \ifdate{equals=\year-12-25}{\tikzset{every day/.style={fill=orange!40}}}{} % Xmas
    \ifdate{equals=\nextYear-01-01}{\tikzset{every day/.style={fill=orange!40}}}{} % New Year's Eve 
    },
 execute at begin day scope=
  {
    % each day is shifted down according to the day of month
    \pgftransformyshift{-1.7*\pgfcalendarcurrentday cm}
  }
];

% Print name of Holidays
% \holiday{\year-01-01}{New Year's Eve}
% \holiday{\year-04-17}{Maundy Thursday}
\end{tikzpicture}
\end{center}
\end{document}

You can export this calendar at https://www.sharelatex.com/project/54c25375a50cfdaa3f0ed85b