What Is a Sex Diary? A Tiny Look at the Format and Why People Keep One
May 15 2026 – Aysegul Uslu
A sex diary is a small prompted journal where you log intimate moments - usually with space for the date, the setting, and a quick rating. The format has been around for years, sits somewhere between a guided journal and a logbook, and has a small but steady audience of people who actually use one.
This guide walks you through what the format actually looks like, why some people keep one, and how a prompted version (like A Tiny Sex Diary from the Brass Monkey Tiny Diary Series) differs from grabbing a blank notebook off the shelf.
5 Key Takeaways
-
A sex diary is a personal record of intimate moments, usually with prompts for the date, the setting, and a rating or note about the experience. The format is closer to a guided journal than a blank notebook.
-
People keep them for memory, self-reflection, or just for fun. It's the same impulse as keeping a travel journal, a food diary, or a list of every concert you've been to.
-
A prompted sex diary takes about 30 seconds to fill in. That's part of the appeal - low commitment, finished entries, no staring at a blank page wondering what to write.
-
Most pocket-format sex diaries (including Brass Monkey's) are 2.75" by 3.75" with around 112 pages. Small enough to live in a nightstand drawer, big enough to last years.
-
It can work as a gift, but only for the right recipient. Long-term couples and bachelorette parties land best. New relationships, conservative friends, and most coworkers do not.
What a Sex Diary Actually Is
You may have come across the term in a few different places before landing here. It's an HBO docuseries (eight New Yorkers talking about their dating lives). It's a long-running NY Magazine column where anonymous contributors log a week of their lives. It's also a tracking app and a category of physical journal. The journal is what this guide is about, and it's the one you'd actually own.
The format in plain terms
A sex diary is a small physical book with prompts on each page for recording an intimate experience. Each page typically gives you space for:
-
The date
-
A location or setting
-
A short summary or note
-
A rating or score
That's the entire format. No essays, no long entries, nothing literary. The closest comparison is a workout log or a wine-tasting notebook - the structure is built for fast, low-effort entries that you can flip back through later.
How common the format actually is
More common than you'd expect, less common than something like a regular journal. The format has its own quiet user base - people who've kept one for years, couples who fill them in together, and a steady gift-giving audience that buys them for bachelorette parties and anniversaries. Not mainstream, but not fringe either.
No stigma attached to it
No more than keeping a travel journal, a food log, or a list of every concert you've ever been to. The only thing that makes it feel different is the subject matter, and that part fades the second you've actually written your first entry. Most people who buy one stop overthinking it within the first week.
Why People Keep a Sex Diary
The honest answer is that people keep sex diaries for the same range of reasons they keep any other diary. The intimate subject matter is the only thing that makes it feel different on the surface.
Memory
A surprising number of long-term couples discover that they can't quite remember when something happened, or where, or what made it stand out. A diary fills that gap the same way a travel journal does. Five years from now, "the cabin trip in October" reads better than "sometime around our anniversary, I think."
Self-reflection
For some people, it's a way to track patterns. What worked, what didn't, what they liked, what they didn't. The same instinct that makes people keep food diaries to figure out what makes them feel sluggish, applied to a different part of life. Useful for some, completely uninteresting to others.
The novelty of having one
For a lot of buyers, the appeal is that it's a slightly silly, slightly transgressive thing to own. It sits in the nightstand, it gets pulled out occasionally, and the act of filling it in is itself part of the fun. Same energy as keeping a tip jar at home or labeling your home bar like an actual bar. Not strictly necessary. Definitely entertaining.
As a couple's project
This is more common than you'd think. Two people in a long-term relationship buy a diary, agree to fill it in together, and the act of doing it becomes part of the relationship. It's not therapy, but it's also not nothing. The conversation that happens while you're filling in the page is often the actual point.
How a Prompted Sex Diary Differs From a Blank Notebook
This is where the format actually earns its keep. You could in theory do all of this in any spare notebook lying around, but most people who try that route abandon it after two entries. Here's why a prompted format works better.
No blank-page paralysis
The single biggest reason blank notebooks fail as journals is that nobody knows what to write. A prompted diary fills in the structure for you:
-
A date field
-
A location or setting field
-
A short summary or note section
-
A rating, score, or rank
You're not writing an essay. You're filling in a form that takes 30 seconds. That low time commitment is what keeps it actually getting used past the first week.
Consistency across entries
Because every page has the same prompts, the entries become comparable across time. You can flip back through and notice patterns, find specific entries quickly, or compare notes over months and years. A blank notebook gives you a wall of unstructured text that's harder to navigate later.
The right amount of privacy
A blank notebook entry can read like an embarrassing letter if anyone ever finds it. A prompted entry, with its short fields and rating system, reads more like a logbook. For most users that's a positive, since the format does the work of keeping things matter-of-fact. Brass Monkey's pocket format takes this further - at 2.75" by 3.75", the book is small enough to live discreetly in a nightstand drawer rather than sitting on a bookshelf for visitors to wonder about.
What Goes Inside a Sex Diary
The contents are less interesting than the name implies, which is part of why the format works. A typical filled-in entry includes:
-
A date and a location
-
A few words about the situation or who was involved
-
A rating, score, or note about how it ranked
-
Occasionally, a one-line memory or detail worth remembering
That's it. There's no requirement to write paragraphs, no expectation of literary effort, no need to be detailed. Most people fill in entries the same way they'd log a workout or a meal: quickly, without overthinking, with just enough information to remember it later.
A Tiny Sex Diary specifically gives you 112 pages, each one designed for a single entry. That's a lot of pages for what is, by design, a low-frequency activity. For most users, a single book lasts years.
Sex Diary as a Gift: When It Works, When It Doesn't
It depends entirely on the recipient. There are very few small gifts where the relationship between giver and receiver matters more than this one.
When it works
A sex diary lands well as a gift in a few specific situations:
-
Bachelorette parties and bridal showers - The gift table at most hen-dos already includes at least one cheeky item, and a tiny sex diary is a tamer pick than most of what tends to show up there.
-
Long-term couples celebrating an anniversary - A small, slightly silly gift that the couple can use together, especially for the friend who's been with their partner for ten years and has run out of things to be surprised by.
-
The friend who already owns multiple Brass Monkey items - If their nightstand already has a Tiny Diary for Tiny Thoughts and a Definitely Not My Passwords diary, this is a logical addition rather than a leap.
-
A gag gift with a wink - Wrapped alongside a more conventional gift for someone whose sense of humor you know well.
When it doesn't
There's a much longer list of situations where this is the wrong gift, and being honest about it saves you a lot of awkward moments:
-
New relationships where you don't yet know the other person's sense of humor
-
Coworkers in almost every situation
-
Any recipient who'd be embarrassed rather than amused
-
Conservative family members
-
Anyone you wouldn't already make a slightly off-color joke around
The general rule is that if you'd hesitate to make the joke out loud, this isn't the right gift. If you're already the friend who shows up to the bachelorette party with the inappropriate gift on purpose, you already know the answer.
For recipients in the "no" column, a different small-format gift will land better. A regular Tiny Diary Series entry like Tiny Hopes and Dreams or Future Blackmail Tiny Diary hits the same novelty-gift spot without the social risk.
Frequently Asked Questions
How big is a typical pocket sex diary?
The Brass Monkey format is 2.75" wide by 3.75" tall, with 112 pages. Most pocket-format sex diaries on the market are similar - small enough to fit in a nightstand drawer or a bag, but with enough pages to last several years for most users.
Are there prompts on every page or is it mostly blank?
Prompted, not blank. Each page in A Tiny Sex Diary includes space for the date, the location, a short summary of the experience, and a rating. The structure is part of why it gets used - blank pages tend to go unfilled for long stretches, while prompted pages take 30 seconds.
Is this meant for couples or individuals?
Either. Some people use it solo as a personal record. Some couples fill it in together as a shared project. The format doesn't require one approach over the other, and how you use it is up to you.
Does it actually make a good anniversary gift?
For long-term couples with a sense of humor about themselves, yes. It works less well as an early-relationship gift or for couples who'd find the topic awkward to bring up. The safer read is to give it to a friend's couple rather than your own partner unless you're certain they'd like it.
What's the difference between A Tiny Sex Diary and a regular journal?
The prompts. A regular journal gives you blank pages. A Tiny Sex Diary gives you structured fields for date, location, summary, and rating, which makes entries fast to fill in and easy to flip back through. Same difference as a blank notebook versus a guided journal in any other category.
Where should I keep it?
A nightstand drawer is the standard answer. The pocket size makes it easy to tuck away, and the discreet felt-and-foil cover doesn't announce itself the way a brightly labeled book would. Some people keep it in a bag or with other journals - it's small enough to travel.