Free Grammar Check: 12 Mistakes That Make Good Writing Look Careless
A spelling mistake is forgivable. A grammar mistake is the one people remember, because it is the one that makes a reader stop, go back, and read the sentence twice. Worse, the mistakes that damage a piece of writing most are exactly the ones your word processor will not underline: every word in "their is no reason for this" is spelled correctly.
This guide covers the mistakes that slip through, why automatic spell-check cannot see them, and how to proofread a document so they do not reach your reader. You can work through your own text as you read, using the free Grammar & Writing Checker, which runs entirely inside your browser and never uploads what you write.
Why spell-check misses the mistakes that matter
A spell-checker asks one question of each word: is this in the dictionary? "Their", "there" and "they're" all are. So are "its" and "it's", "affect" and "effect", "then" and "than", "lose" and "loose". Every one of those is a real word, so every one of them sails past untouched.
Catching them needs a second question: does this word make sense here, next to the words around it? That is a grammar check rather than a spell check, and it is the difference between a tool that finds typos and a tool that finds mistakes.
The 12 mistakes readers notice first
1. its and it's
"It's" is short for "it is" or "it has". "Its" is the possessive, and it has no apostrophe - like "his" and "hers". If you can say "it is" in its place, use the apostrophe. The company lost its licence is right; it's been a long year is right.
2. their, there and they're
"Their" belongs to them, "there" is a place or the "there is" construction, and "they're" is "they are". The error that appears most often in real documents is "their is" at the start of a sentence, followed closely by "there car" and "there writing".
3. your and you're
"You're welcome" is "you are welcome". "Your welcome" is a welcome that belongs to you, which is almost never what anyone means.
4. should of, could of, would of
This one comes from speech. "Should have" contracts to "should've", which sounds exactly like "should of". Written down it is always have: should have, could have, would have, might have, must have.
5. affect and effect
"Affect" is almost always the verb: the delay affected our schedule. "Effect" is almost always the noun: the effect of the delay was serious. The exception that trips people up is "to effect change", meaning to bring it about - rare enough that you can safely follow the simple rule.
6. then and than
"Than" compares: cheaper than last year. "Then" is about time or sequence: first this, then that. "More then enough" is one of the most common errors in business writing.
7. we was, they was
Was goes with I, he, she and it. Were goes with we, you and they. The one real exception is the subjunctive - "if I were you" - which is correct and deliberate.
8. a and an
"An" goes before a vowel sound, not a vowel letter. So it is an hour and an MBA, but a university and a European partner, because those start with a "y" sound.
9. Repeated words
"The the", "and and", "a a". Your eye reads straight over them because you know what the sentence is supposed to say. They usually appear where a sentence was edited halfway through, which is exactly where you stop paying attention.
10. Double spaces and stray punctuation
Two spaces between words, a space before a comma or a full stop, a missing space after one. Individually trivial, collectively the thing that makes a document look as though nobody read it before sending.
11. Unbalanced brackets and quotation marks
An opening bracket with no closing one, or an odd number of quotation marks, almost always means a sentence was cut short during editing and something is missing.
12. Sentences that never end
Not strictly an error, but the most common reason a clear idea reads as a confusing one. If a sentence runs past about 30 words, it usually contains two sentences that have not been separated yet.
The style problems that are not errors
Beyond the mistakes, there is a layer of habits that make writing harder work than it needs to be.
Padding phrases. "Due to the fact that" is "because". "In order to" is "to". "At this point in time" is "now". "Has the ability to" is "can". Every one of these can be cut without losing a word of meaning.
Filler words. Very, really, basically, actually, literally, simply, quite, absolutely. Delete them and the sentence almost always gets stronger, because the words that remain have to carry the weight themselves.
The passive voice. "The report was written by the team" tells you the same thing as "the team wrote the report" in three more words, and hides who did it. The passive has its uses - when the actor is unknown or irrelevant - but as a default it drains energy from a paragraph.
Cliches. At the end of the day, thinking outside the box, low-hanging fruit. A reader skims past a phrase they have seen a thousand times, which means they skim past your point too.
Repeated sentence openings. Three sentences in a row starting with "The" or "This" is a rhythm problem your reader feels without being able to name.
How to actually proofread
Writing and proofreading are different jobs, and trying to do both at once is why mistakes survive. A workable order:
First, finish the draft without editing anything. Second, leave it alone - an hour is enough, overnight is better. You cannot proofread a sentence you wrote five minutes ago, because you read what you meant rather than what you typed. Third, run a grammar check and work through the suggestions one at a time, accepting the clear ones and thinking about the rest. Fourth, read the whole thing aloud, which catches rhythm, run-on sentences and missing words that no tool will ever find. Finally, check the things a checker cannot verify: names, dates, figures, and whether the link actually goes where you say it does.
Reading ease, grade level, and what the numbers are for
Two scores tell you most of what you need to know about how hard your writing is to read.
Flesch Reading Ease runs from 0 to 100. Above 80 is very easy, 70 to 80 is easy, 60 to 70 is plain English, 50 to 60 is fairly hard, and below 50 is hard work. Most newspapers sit between 55 and 70.
Flesch-Kincaid grade level converts the same measurements into a US school year - the level of education a reader needs to follow the text first time. Grade 8 to 10 suits a general audience. Government plain-language guidance typically aims at grade 8.
Both are calculated from just two things: how long your sentences are, and how many syllables your words have. That makes them crude - they cannot tell you whether a sentence is *good* - but it also makes them honest. If your score is poor, your sentences are too long or your words are too complicated, and both are fixable.
Do not chase the number. A legal contract or a research paper is supposed to be harder to read than a blog post, which is why the Grammar & Writing Checker lets you pick a writing goal - blog post, email, business report or academic - and relaxes the sentence-length and passive-voice checks to match.
British and American English
The two variants differ in more ways than most people realise: colour/color, organise/organize, centre/center, travelling/traveling, defence/defense, licence/license, programme/program, grey/gray, aluminium/aluminum, favourite/favorite. Around 295 common word pairs differ.
Mixing them in one document is the actual mistake. Pick one, apply it everywhere, and be consistent - particularly in anything that will be read by a client, an examiner or an employer in a specific country. The tool accepts either spelling of a word it knows, flags a spelling from the variant you did not choose, and will convert an entire document from one to the other in a single click.
Why a browser-based checker
The best-known grammar services send every word you type to a server. For a blog post that may not matter. For a contract, a medical letter, a legal filing, an unpublished manuscript or a piece of coursework subject to an academic integrity policy, it matters a great deal.
A checker that runs in your browser reads your text in the same place you wrote it. Nothing is transmitted, nothing is stored on anybody's server, no account is needed, and once the page has loaded it works with the connection off. It is also instant, because there is no round trip to wait for.
What a grammar checker cannot do
Use it honestly and it will save you. Trust it blindly and it will let you down.
A checker does not know your subject, so it cannot tell you a figure is wrong or a claim is unsupported. It does not know your reader, so it cannot tell you the tone is off. It cannot tell you the second paragraph belongs at the top, or that a whole section could go. And it will occasionally flag something that is perfectly correct, because "his wont", "she lets the team decide" and "if I were you" all look odd to a rule.
That is why every suggestion in this tool comes with a sentence explaining it. Read the explanation, then decide. A proofreader that makes you a better writer is worth more than one that quietly edits you.
Try it
Paste your text into the Grammar & Writing Checker and see what it finds. It is free, there is no sign-up, and your writing does not leave your computer.
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