Why is the bottom margin ALWAYS bigger than the other margins even with the package geometry

footergeometryheader-footermarginstextheight

When I set my margins to 25 mm, the bottom margin always turns out to be 28 mm. If I set the bottom margin to 22 mm, it becomes 23 mm, which is too small. Why does this happen? How can I fix this problem? I want all my margins to be 25 mm.

I've tried browsing the internet. I've looked at the manual for the package geometry on CTAN. Still, I just can't solve this problem.

Here's a code sample:

\documentclass[a5paper,12pt]{report}

\author{William Faulkner}
\date{1930}
\title{A Rose For Emily}

\usepackage[
top=25mm,
bottom=25mm,
left=25mm,
right=25mm,
footnotesep=0mm,
ignoreheadfoot,
layoutoffset=0mm,
marginratio=1:1,
offset=0mm,
scale=1,
]{geometry}

\usepackage[
hyphens
]{url}
 \usepackage[
 hidelinks
 ]{hyperref}

\begin{document}
\maketitle
\pagenumbering{gobble}
\tableofcontents
\newpage
\pagenumbering{arabic}

\section*{Chapter I}

\label{s1}
\addcontentsline{toc}{section}{\nameref{s1}}
WHEN Miss Emily Grierson died, our whole town went to her 
funeral: the men through a sort of respectful affection for a 
fallen monument, the women mostly out of curiosity to see the 
inside of her house, which no one save an old man-servant--a 
combined gardener and cook--had seen in at least ten years.

It was a big, squarish frame house that had once been white, 
decorated with cupolas and spires and scrolled balconies in the 
heavily lightsome style of the seventies, set on what had once 
been our most select street. But garages and cotton gins had 
encroached and obliterated even the august names of that 
neighborhood; only Miss Emily's house was left, lifting its 
stubborn and coquettish decay above the cotton wagons and the 
gasoline pumps-an eyesore among eyesores. And now Miss Emily had 
gone to join the representatives of those august names where 
they lay in the cedar-bemused cemetery among the ranked and 
anonymous graves of Union and Confederate soldiers who fell at 
the battle of Jefferson.

Alive, Miss Emily had been a tradition, a duty, and a care; a 
sort of hereditary obligation upon the town, dating from that 
day in 1894 when Colonel Sartoris, the mayor--he who fathered 
the edict that no Negro woman should appear on the streets 
without an apron-remitted her taxes, the dispensation dating 
from the death of her father on into perpetuity. Not that Miss 
Emily would have accepted charity. Colonel Sartoris invented an 
involved tale to the effect that Miss Emily's father had loaned 
money to the town, which the town, as a matter of business, 
preferred this way of repaying. Only a man of Colonel Sartoris' 
generation and thought could have invented it, and only a woman 
could have believed it.

When the next generation, with its more modern ideas, became 
mayors and aldermen, this arrangement created some little 
dissatisfaction. On the first of the year they mailed her a tax 
notice. February came, and there was no reply. They wrote her a 
formal letter, asking her to call at the sheriff's office at her 
convenience. A week later the mayor wrote her himself, offering 
to call or to send his car for her, and received in reply a note 
on paper of an archaic shape, in a thin, flowing calligraphy in 
faded ink, to the effect that she no longer went out at all. The 
tax notice was also enclosed, without comment.

They called a special meeting of the Board of Aldermen. A 
deputation waited upon her, knocked at the door through which no 
visitor had passed since she ceased giving china-painting 
lessons eight or ten years earlier. They were admitted by the 
old Negro into a dim hall from which a stairway mounted into 
still more shadow. It smelled of dust and disuse--a close, dank 
smell. The Negro led them into the parlor. It was furnished in 
heavy, leather-covered furniture. When the Negro opened the 
blinds of one window, they could see that the leather was 
cracked; and when they sat down, a faint dust rose sluggishly 
about their thighs, spinning with slow motes in the single 
sun-ray. On a tarnished gilt easel before the fireplace stood a 
crayon portrait of Miss Emily's father.

They rose when she entered--a small, fat woman in black, with a 
thin gold chain descending to her waist and vanishing into her 
belt, leaning on an ebony cane with a tarnished gold head. Her 
skeleton was small and spare; perhaps that was why what would 
have been merely plumpness in another was obesity in her. She 
looked bloated, like a body long submerged in motionless water, 
and of that pallid hue. Her eyes, lost in the fatty ridges of 
her face, looked like two small pieces of coal pressed into a 
lump of dough as they moved from one face to another while the 
visitors stated their errand.

She did not ask them to sit. She just stood in the door and 
listened quietly until the spokesman came to a stumbling halt. 
Then they could hear the invisible watch ticking at the end of 
the gold chain.

Her voice was dry and cold. "I have no taxes in Jefferson. 
Colonel Sartoris explained it to me. Perhaps one of you can gain 
access to the city records and satisfy yourselves."

"But we have. We are the city authorities, Miss Emily. Didn't 
you get a notice from the sheriff, signed by him?"

"I received a paper, yes," Miss Emily said. "Perhaps he 
considers himself the sheriff . . . I have no taxes in 
Jefferson."

"But there is nothing on the books to show that, you see We must 
go by the--"

"See Colonel Sartoris. I have no taxes in Jefferson."

"But, Miss Emily--"

"See Colonel Sartoris." (Colonel Sartoris had been dead almost 
ten years.) "I have no taxes in Jefferson. Tobe!" The Negro 
appeared. "Show these gentlemen out."
\end{document}

PS: I am not the author of this short story.

Best Answer

You have contradictory requests. The text height you get from your options is

455.24411pt

The pages without titles have 31 lines, with

\topskip=12pt
\baselineskip=14.5pt

If you compute

12 + 30 · 14.5 = 447

so there are 8.24111pt that cannot be covered with text, which correspond to 2.9mm, which is what you're measuring.

Why the computation? A “normal” first line will have its baseline at \topskip distance from the top margin, the following lines will be \baselineskip apart. In the chapter page, the first line will have a lower baseline, but there is no real problem, because the vertica space after a section title is flexible.

Here's the picture (I added the shoframe option to geometry):

enter image description here

If you add \flushbottom in the document preamble the picture would be

enter image description here

but the space is obtained by increasing the gap between paragraphs

enter image description here

which is out of question.

You need to do some arithmetic in order to distribute the 8.24111pt across the interline spaces. Here it is:

(455.24411 - 12)/30 = 14.77480366666666666666
14.77480366666666666666/14.5 = 1.01895197701149425287

So let's add

\linespread{1.01895}

and the picture will be

enter image description here

The last baseline sits where you expect it and there's no gap between paragraphs.

Here's the full code, with some adjustments to avoid problems with hyperref.

\documentclass[a5paper,12pt]{report}

\author{William Faulkner}
\date{1930}
\title{A Rose For Emily}

\usepackage[
  showframe,
  top=25mm,
  bottom=25mm,
  left=25mm,
  right=25mm,
  footnotesep=0mm,
  ignoreheadfoot,
  layoutoffset=0mm,
  marginratio=1:1,
  offset=0mm,
  scale=1,
]{geometry}

\usepackage[
  hyphens
]{url}
\usepackage[
  hidelinks
]{hyperref}

\setcounter{secnumdepth}{-2} % no numbering
\setcounter{tocdepth}{1} % sections in the TOC

\linespread{1.01895}
\flushbottom

\begin{document}

\pagenumbering{Alph}
\maketitle

\clearpage
\pagenumbering{alph}
\pagestyle{empty}
\tableofcontents
\thispagestyle{empty}

\clearpage
\pagenumbering{arabic}
\pagestyle{plain}

\section{Chapter I}\label{s1}

WHEN Miss Emily Grierson died, our whole town went to her 
funeral: the men through a sort of respectful affection for a 
fallen monument, the women mostly out of curiosity to see the 
inside of her house, which no one save an old man-servant--a 
combined gardener and cook--had seen in at least ten years.

It was a big, squarish frame house that had once been white, 
decorated with cupolas and spires and scrolled balconies in the 
heavily lightsome style of the seventies, set on what had once 
been our most select street. But garages and cotton gins had 
encroached and obliterated even the august names of that 
neighborhood; only Miss Emily's house was left, lifting its 
stubborn and coquettish decay above the cotton wagons and the 
gasoline pumps-an eyesore among eyesores. And now Miss Emily had 
gone to join the representatives of those august names where 
they lay in the cedar-bemused cemetery among the ranked and 
anonymous graves of Union and Confederate soldiers who fell at 
the battle of Jefferson.

Alive, Miss Emily had been a tradition, a duty, and a care; a 
sort of hereditary obligation upon the town, dating from that 
day in 1894 when Colonel Sartoris, the mayor--he who fathered 
the edict that no Negro woman should appear on the streets 
without an apron-remitted her taxes, the dispensation dating 
from the death of her father on into perpetuity. Not that Miss 
Emily would have accepted charity. Colonel Sartoris invented an 
involved tale to the effect that Miss Emily's father had loaned 
money to the town, which the town, as a matter of business, 
preferred this way of repaying. Only a man of Colonel Sartoris' 
generation and thought could have invented it, and only a woman 
could have believed it.

When the next generation, with its more modern ideas, became 
mayors and aldermen, this arrangement created some little 
dissatisfaction. On the first of the year they mailed her a tax 
notice. February came, and there was no reply. They wrote her a 
formal letter, asking her to call at the sheriff's office at her 
convenience. A week later the mayor wrote her himself, offering 
to call or to send his car for her, and received in reply a note 
on paper of an archaic shape, in a thin, flowing calligraphy in 
faded ink, to the effect that she no longer went out at all. The 
tax notice was also enclosed, without comment.

They called a special meeting of the Board of Aldermen. A 
deputation waited upon her, knocked at the door through which no 
visitor had passed since she ceased giving china-painting 
lessons eight or ten years earlier. They were admitted by the 
old Negro into a dim hall from which a stairway mounted into 
still more shadow. It smelled of dust and disuse--a close, dank 
smell. The Negro led them into the parlor. It was furnished in 
heavy, leather-covered furniture. When the Negro opened the 
blinds of one window, they could see that the leather was 
cracked; and when they sat down, a faint dust rose sluggishly 
about their thighs, spinning with slow motes in the single 
sun-ray. On a tarnished gilt easel before the fireplace stood a 
crayon portrait of Miss Emily's father.

They rose when she entered--a small, fat woman in black, with a 
thin gold chain descending to her waist and vanishing into her 
belt, leaning on an ebony cane with a tarnished gold head. Her 
skeleton was small and spare; perhaps that was why what would 
have been merely plumpness in another was obesity in her. She 
looked bloated, like a body long submerged in motionless water, 
and of that pallid hue. Her eyes, lost in the fatty ridges of 
her face, looked like two small pieces of coal pressed into a 
lump of dough as they moved from one face to another while the 
visitors stated their errand.

She did not ask them to sit. She just stood in the door and 
listened quietly until the spokesman came to a stumbling halt. 
Then they could hear the invisible watch ticking at the end of 
the gold chain.

Her voice was dry and cold. "I have no taxes in Jefferson. 
Colonel Sartoris explained it to me. Perhaps one of you can gain 
access to the city records and satisfy yourselves."

"But we have. We are the city authorities, Miss Emily. Didn't 
you get a notice from the sheriff, signed by him?"

"I received a paper, yes," Miss Emily said. "Perhaps he 
considers himself the sheriff . . . I have no taxes in 
Jefferson."

"But there is nothing on the books to show that, you see We must 
go by the--"

"See Colonel Sartoris. I have no taxes in Jefferson."

"But, Miss Emily--"

"See Colonel Sartoris." (Colonel Sartoris had been dead almost 
ten years.) "I have no taxes in Jefferson. Tobe!" The Negro 
appeared. "Show these gentlemen out."

\end{document}

I didn't change the " quotes, but you should, for example

``See Colonel Sartoris.''

With " you get

enter image description here

With the suggested code you'd get

enter image description here