Edit:
In my original question I unfortunately strip out three lines:
\usepackage{calc} immediately after document class and
\setlength{\marginwidth}{\marginparsep+\marginparwidth} \setlength{\headwidth}{\textwidth+\marginwidth} before \usepackage{adjmulticol}, which shows, why I actually nested a adjmulticol and idxlayout.
The length \marginwidth I use for calculation of \headwidth and other items in my real case (like chapter title layout, new environments which are extended into outer margin). I hope that my questions is more clear.
Wider text width i need for placing longer indices in index that they are not broken unnecessary into two lines.
\documentclass[twoside,openright]{memoir} \usepackage{calc}% added in eddit \setstocksize{297mm}{210mm} % A4 \settrimmedsize{\stockheight}{\stockwidth}{*} % A4 \newlength{\marginwidth} \settypeblocksize{247mm}{120mm}{*} \setulmargins{25mm}{*}{1} % upper, lower margin, ratio \setlrmarginsandblock{30mm}{60mm}{*}% spinner, outer margin, ratio \checkandfixthelayout \setlength{\marginparwidth}{45mm} \setlength{\marginparsep}{5mm} \setlength{\marginwidth}{\marginparsep+\marginparwidth}% added in edit \setlength{\headwidth}{\textwidth+\marginwidth}% added in edit %---------------------------------------------------------------% \usepackage{adjmulticol} \usepackage[columns=3]{idxlayout} \makeindex \begin{document} \mainmatter \chapter{Test of indexing} \index{Alpha} alpha(a) \index{Alpha!alpha} alpha(a) \index{Alpha!alpha!a} alpha(b) \index{Alpha!alpha!b} alpha(c) \index{Alpha!alpha!c} alpha(d) \index{Alpha!alpha!d} beta(a) \index{Alpha!beta} \index{Alpha!beta!a} beta(b) \index{Alpha!beta!b} beta(c) \index{Alpha!beta!c} \section{Beta, Delta, Epsilon, Eta} \index{Beta} alpha(a) \index{Beta!alpha} alpha(a) \index{Beta!alpha!a} alpha(b) \index{Beta!alpha!b} alpha(c) \index{Beta!alpha!c} alpha(d) \index{Beta!alpha!d} beta(a) \index{Beta!beta} \index{Beta!beta!a} beta(b) \index{Beta!beta!b} beta(c) \index{Beta!beta!c} \index{Delta} alpha(a) \index{Delta!alpha} alpha(a) \index{Delta!alpha!a} alpha(b) \index{Delta!alpha!b} alpha(c) \index{Delta!alpha!c} alpha(d) \index{Delta!alpha!d} beta(a) \index{Delta!beta} \index{Delta!beta!a} beta(b) \index{Delta!beta!b} beta(c) \index{Delta!beta!c} \index{Epsilon} alpha(a) \index{Epsilon!alpha} alpha(a) \index{Epsilon!alpha!a} alpha(b) \index{Epsilon!alpha!b} alpha(c) \index{Epsilon!alpha!c} alpha(d) \index{Epsilon!alpha!d} beta(a) \index{Epsilon!beta} \index{Epsilon!beta!a} beta(b) \index{Epsilon!beta!b} beta(c) \index{Epsilon!beta!c} \index{Eta} alpha(a) \index{Eta!alpha} alpha(a) \index{Eta!alpha!a} alpha(b) \index{Eta!alpha!b} alpha(c) \index{Eta!alpha!c} alpha(d) \index{Eta!alpha!d} beta(a) \index{Eta!beta} \index{Eta!beta!a} beta(b) \index{Eta!beta!b} beta(c) \index{Eta!beta!c} \section{Gamma, Kappa, Lambda, Omega} \index{Gama} alpha(a) \index{Gamma!alpha} alpha(a) \index{Gamma!alpha!a} alpha(b) \index{Gamma!alpha!b} alpha(c) \index{Gamma!alpha!c} alpha(d) \index{Gamma!alpha!d} beta(a) \index{Gamma!beta} \index{Gamma!beta!a} beta(b) \index{Gamma!beta!b} beta(c) \index{Gamma!beta!c} \index{Kappa} alpha(a) \index{Kappa!alpha} alpha(a) \index{Kappa!alpha!a} alpha(b) \index{Kappa!alpha!b} alpha(c) \index{Kappa!alpha!c} alpha(d) \index{Kappa!alpha!d} beta(a) \index{Kappa!beta} \index{Kappa!beta!a} beta(b) \index{Kappa!beta!b} beta(c) \index{Kappa!beta!c} \index{Lambda} alpha(a) \index{Lambda!alpha} alpha(a) \index{Lambda!alpha!a} alpha(b) \index{Lambda!alpha!b} alpha(c) \index{Lambda!alpha!c} alpha(d) \index{Lambda!alpha!d} beta(a) \index{Lambda!beta} \index{Lambda!beta!a} beta(b) \index{Lambda!beta!b} beta(c) \index{Lambda!beta!c} \index{Omega} alpha(a) \index{Omega!alpha} alpha(a) \index{Omega!alpha!a} alpha(b) \index{Omega!alpha!b} alpha(c) \index{Omega!alpha!c} alpha(d) \index{Omega!alpha!d} beta(a) \index{Omega!beta} \index{Omega!beta!a} beta(b) \index{Omega!beta!b} beta(c) \index{Omega!beta!c} \section{Pi, Phi, Psi, Rho} \index{Pi} alpha(a) \index{Pi!alpha} alpha(a) \index{Pi!alpha!a} alpha(b) \index{Pi!alpha!b} alpha(c) \index{Pi!alpha!c} alpha(d) \index{Pi!alpha!d} beta(a) \index{Pi!beta} \index{Pi!beta!a} beta(b) \index{Pi!beta!b} beta(c) \index{Pi!beta!c} \index{Phi} alpha(a) \index{Phi!alpha} alpha(a) \index{Phi!alpha!a} alpha(b) \index{Phi!alpha!b} alpha(c) \index{Phi!alpha!c} alpha(d) \index{Phi!alpha!d} beta(a) \index{Phi!beta} \index{Phi!beta!a} beta(b) \index{Phi!beta!b} beta(c) \index{Phi!beta!c} \index{Psi} alpha(a) \index{Psi!alpha} alpha(a) \index{Psi!alpha!a} alpha(b) \index{Psi!alpha!b} alpha(c) \index{Psi!alpha!c} alpha(d) \index{Psi!alpha!d} beta(a) \index{Psi!beta} \index{Psi!beta!a} beta(b) \index{Psi!beta!b} beta(c) \index{Psi!beta!c} \index{Rho} alpha(a) \index{Rho!alpha} alpha(a) \index{Rho!alpha!a} alpha(b) \index{Rho!alpha!b} alpha(c) \index{Rho!alpha!c} alpha(d) \index{Rho!alpha!d} beta(a) \index{Rho!beta} \index{Rho!beta!a} beta(b) \index{Rho!beta!b} beta(c) \index{Rho!beta!c} \section{Sigma, Theta, Xi} \index{Sigma} alpha(a) \index{Sigma!alpha} alpha(a) \index{Sigma!alpha!a} alpha(b) \index{Sigma!alpha!b} alpha(c) \index{Sigma!alpha!c} alpha(d) \index{Sigma!alpha!d} beta(a) \index{Sigma!beta} \index{Sigma!beta!a} beta(b) \index{Sigma!beta!b} beta(c) \index{Sigma!beta!c} \index{Theta} alpha(a) \index{Theta!alpha} alpha(a) \index{Theta!alpha!a} alpha(b) \index{Theta!alpha!b} alpha(c) \index{Theta!alpha!c} alpha(d) \index{Theta!alpha!d} beta(a) \index{Theta!beta} \index{Theta!beta!a} beta(b) \index{Theta!beta!b} beta(c) \index{Theta!beta!c} \index{Xi} alpha(a) \index{Xi!alpha} alpha(a) \index{Xi!alpha!a} alpha(b) \index{Xi!alpha!b} alpha(c) \index{Xi!alpha!c} alpha(d) \index{Xi!alpha!d} beta(a) \index{Xi!beta} \index{Xi!beta!a} beta(b) \index{Xi!beta!b} beta(c) \index{Xi!beta!c} \backmatter \begin{adjmulticols}{1}{0mm}{-\marginwidth}\Large \printindex \end{adjmulticols} \end{document}