That usually relies on the writer's style and skill…

Look how Iris Murdoch introduces great and irrelevant details of menus and cooking, when it wasn't in any way necessary even to mention that anyone was eating.

Notice when Robert A Heinlein lists every move in a game of mental chess which has no real effect on the story or - more than once - describes every action involved in checking whether a vintage car might be immediately ready for the road, rather than simply pressing the starter!

See whether Allan W. Eckert had any need to describe the driver's day, breakfast or family life when he could simply have stated that a truck smashed into his hero's car.

If the Question persists, stick to what detail is actually necessary.

"He drew a gun and shot the man dead" is fine in itself.

"He pulled out a pistol and plugged the lead 'til the man was dead" is more stylish and whether it's more helpful is a matter of choice, isn't it?

"He hauled his tried and trusted, nine-shot Mauser .455 Parabellum from the tooled and monogrammed leather holster behind his hip, raised the silver-plated weapon in a two-handed grip and took slow and careful aim then gently squeezed off a single shot that dropped the victim in his tracks" is at best highly questionable, and probably a lot more pretentious than practical.

Pick your idea first.

What is it? And how do you want to approach it?

All styles are fine as long as the target audience is satisfied. You don't want to bore airport novel readers with a lot of detail, and you don't want to ruffle feathers by writing an outline for a research paper.

Indiana Jones was an entertaining swashbuckler flick - to develop its entertainment value, any idea must lose excess detail. The focus must lie on the spectacle - jumps, ducks, sways, headshots, near fall-to-death misses.

It is not easy to get it right in one go. This is true for everyone, even experienced writers. Every major piece undergoes a rewrite. So - get through the first draft. Then read your own work like a critic and decide for yourself. Let the thought that you spent months, possibly years, on the manuscript not bother you while you analyse.

A typical way to lower the number of rewrites is to use the outlining method. Plot your tale before you write it.

A high level overview before the grunt work helps make preemptive changes. When you realise you have the two main characters talking at a table and drinking for a whole chapter, you will know your mistake.

Wish you good luck with your book!

Most of the answers on here are adequate, however, I do not feel that they get straight to the point.

How much detail is too much?

I've read a few amateur stories online and sometimes the author will include so much detail that the reader gets a little bored or distracted and forgets what the actual story is talking about.

You have answered your own question:
Q: How much detail is too much?
A: When the reader gets a little bored or distracted and forgets what the actual story is talking about.

The details in a "fully expressed medium of text" (that is, a sentence, paragraph, article, book, or voluminous/episodic series) greatly influence attention. The center of attention is the focus.

Superfluous details are details that divert attention away from the focus. Consider the following:

I was dropped off at the usual bus stop that I attend every morning. It is a short stretch of concrete road with green signs, and four houses. There are two houses on each side. Each house is white. The lawns varied in shades of green and brown (it was early fall). When the bus finally arrived, I hopped on. Silence was in the cold air of the bus as students stared at their phones and closed their minds off from the real world to escape into the fantasy of the internet.

The focus of this paragraph is getting on the bus, but yet, all the detail is focusing on the surrounding environment of the bus stop, before abruptly transitioning to hopping on the bus which appeared out of no where.

Necessary details are consistent with the focus. Consider the following:

I came to this large, two-story house with overarching balconies and elegant columns. It was old—very old. I burst open the dusty, wooden double-doors that entered into the house. The room was dark, and had a musty, century-old odor to it. The black and white checkered tile pattern on the floor was heavily worn and coarse. The chandelier dangled askew. This was, no doubt, a dance hall, which told the story of a time long forgotten, when people twirled and danced to a merry tune.

The details in this paragraph dictate that the focus is an old house which had many ballroom-style dances. Every detail describes the age of this house, and the purpose is to give imagery of what the house looks like, and what the ambient atmosphere projects. Without these details, this would be a dull paragraph, and the actual lack of detail would bore and distract.

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Detail is of course only one element of influence for the audience's attention, but it is clearly displayed that it does have a great impact on attention. The detail determines the focus,

so how much detail is too much?

When the details shift attention away from the center of attention.

To answer this question you have to consider the purpose of detail. The purpose of detail is to refine the picture in the reader's head. Readers pull images from their own stock of experiences to build a picture of what they are reading. Each detail you add refines the selection of images they make. If you say "bus" they select an image of the kind of bus they are most familiar with. If you say "red double-decker bus" they probably select an image of a London bus, unless they live in another city with red double-decker buses.

The image in the reader's head will probably never match the image in your head perfectly, unless you have had the exact same experience. The question is, how close do I need the image in the reader's head to be to the image in my head for them to receive the story, its mood and texture as well as its plot, in the way I intend. You add detail until you think the reader's image will be close enough to your own for story purposes.

I disagree with those who say you should leave something to the reader's imagination. That's moot. It all comes from the reader's imagination. You job is to direct that imagination into the right channels so that the reader receives the experience you are attempting to create.

A closely related question is, how closely do you paint each scene and each object in a scene. The more you refine an image, the more important you make that image. Don't make any image more important in a scene than it is in the story, or you will divert the reader's attention away from what matters in the story.

Finally, it is really more about finding the right detail than it is about the amount of detail. Think of it like a database query on the user's stock of experiences. Certain details will pull up certain images whole and intact. A swastika armband may be the only detail you need to pull up the image of a Nazi soldier, for instance. This is what is often called the telling detail, and finding the telling detail is far more important than how much detail you provide. The telling detail can not only pull out a particular object but the entire scene, the entire time and place to which that object belongs. Thus the red double-decker evokes London, the swastika armband evokes Nazi Germany.

Finally, be wary of details that seem contradictory or are hard to integrate. Adding one more term to a database query can turn it from retrieving a very precise image to returning no data at all.

While the existing answers are helpful, they don't address what seems to me the crux of this question. The answers will change depending on what you are writing, for which audience and what effect do you hope to achieve?

For example, I primarily write journalism. The idea is to engage the reader quickly and carry them through to the end of the article. As a general rule it is good to keep descriptive writing to a minimum since it reduces the punchiness and impact of the work. Better instead to pluck a few well-chosen metaphors to help the reader relate what you're describing quickly and easily to their own experience.

Yet even this is subject to change depending on circumstance. A print article is generally subject to a draconian word count and you must be even more sparing with your descriptions. On the other hand if the feature is emotive in nature or is describing an external narrative, you will need to spend some time scene-setting.

Contrast this to the opening sentence of Cormac McCarthy's novel Suttree.

Dear friend now in the dusty clockless hours of the town when the streets lie black and steaming in the wake of the watertrucks and now when the drunk and the homeless have washed up in the lee of walls in alleys or abandoned lots and cats go forth highshouldered and lean in the grim perimeters about, now in these sootblacked brick or cobbled corridors where lightwire shadows make a gothic harp of cellar doors no soul shall walk save you.

This is grandiose to the point of impenetrability. If I tried anything like that, my editors would tear it apart and never employ me again. It's also way beyond the level other answers are suggesting you should take descriptive writing. Yet I find it an extraordinary scene-setter, brilliant in its eloquence. It works because it's well structured and because in the context of the work of a heavyweight novelist, we might expect such constructions.

In summary: your yardstick for measure whether you've got "too much" description depends entirely on the effect you're trying to achieve and your skill at building descriptions.

Daniel's answer is good, but I have an additional "yardstick" which may be helpful:

Part of art, of any art form, is inviting the audience to contribute.

It's even been said this is what makes it art: A return contribution is invited. You supply something yourself as an audience or reader, rather than just having the words flow in at you without you yourself participating.

If you describe every tiny detail to such a degree that nothing is left to the imagination, you wind up with a court deposition, not a story. There's not going to be a great deal of interest, because the reader will not be invited to participate and use his imagination to fill in gaps.

If you consider carefully, you'll likely find that any story which really "pulled you in" was one in which you were actively participating in imagining the details and filling in "how it would have been," rather than one in which you were slavishly noting every last exhaustive detail directly from the author's description.

Other things besides physical descriptions can be left to the imagination too, of course. You need to provide enough detail to spur your reader's imagination to fill in the rest.

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Something which goes along with this:

Don't use description to make your reader's imagination wrong.

If you introduce a character and keep him doing things and saying things for several chapters before you happen to mention that he has very dark skin and pale blonde hair, you are very likely to throw your reader out of the story. She will have come up with her own mental picture of how this character looks by then, and the description, coming so late, will make her feel that she "got it wrong." Really, the author is at fault for such a jolt.

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Physical descriptions are a good thing to include, just don't stop the flow of the story to include them. Don't stop the action. It's not vital that your readers envision every detail just exactly the same way you do. Include enough that they get a colorful (vivid, evocative) picture of the events you depict—fully fleshed out by their own imagination, which you've coaxed into action with your masterful use of descriptive words.

You said it yourself. When the reader cannot concentrate on the story because there are so many adjectives and adverbs, and other details and flourishes. Get other people to read your writing, and they will be able to easily comment on this.

You are also falling into having too much detail if every other word is an adjective or adverb. If you're describing every noun or verb with them, stop it. It's really bad and will lead to the thing I said above. Here's an example:

I furiously knocked on the brown oak door, and impatiently waited for my annoying brother to finally arrive.

That sentence is a little extreme but I have seen things like it in the past. There are many things which would be implied by the story (even though we don't have a 'story' in this example). We can pick out some unnecessary descriptions:

• The brother is annoying. We don't need to describe that because the protagonist would only be furiously knocking on the door if the brother had been doing something bad/annoying.

• The brown oak door. This is really unnecessary. I don't need to be reminded of what a door looks like, it's one of those things you can leave for the reader to imagine. However, if there's a special door, you can describe it. For example, a door with spikes on.

• Impatiently and finally. Impatiently is already implied, and if you wanted to further show this, you could perhaps write another sentence about him doing something impatient. Finally is just completely unnecessary and you don't really need it. It adds an extra not-needed adverb to the sentence.

I think that the amount of detail depends on the author though. It's very difficult to know if you're using too little or too much. So what I would advise is: use your peers to your advantage! Go onto a site like Critique Circle and get it critiqued.