Is bad grammar costing you? Yes and no—it depends.

Whether you spell it correctly as lay-by, or lay-buy, laybuy, or even lay bye (!), I suspect the audience likely to buy with lay-bys probably won’t notice the difference. (American: “layaway”. A lay-by sale is where the seller lays the product by, or away, until the buyer has paid all instalments.)

This is more than merely a grammar Nazi’s concern with language rules, though. If your sales copy is riddled with errors, what does it say about your lack of care for the actual product or service you’re trying to sell me? Or worse, is it an indictment of your lack of care for me, your customer?

In the management consulting work we do, I review countless business websites, contracts, presentations, financial reports and policies and procedures. While I expect an occasional typo or convoluted line editing, severe errors jolt the flow of reading. When I can’t resolve the writer’s intention by the context of the sentence, bad language leads to ambiguity and uncertainty.

Typos happen to us all, especially in quick-fire replies on text apps and tiny screens. I’ve often hit “Send” before proofreading, so I try to not be too judgy—people in glass houses and all that.

In fact, some auto-corrects are quite endearing, or they make for serendipitous metaphors. (Some are hilarious: google the “DYAC” memes for a little dopamine distraction.)

And some rules should be broken. A micro message or Zoom chat is more personal with slang or text speak than the starched tone if we spelt words in full, like “tmrw”, “pls”, or “BRB”.

Regardless of the medium, though, error tolerance is easier when there’s a strong relationship between reader and writer. But without this relationship, first impressions count. In a prospective customer’s first contact with your brand—your website or a social media post—there’s only that first message to judge you by. Errors can literally cost you money.

For example, a UK-based stocking retailer, then named Tights Please, improved sales conversions by 80% after correcting a misspelling of “Tihgts” to “Tights” on their catalogue page. (CXL, 2020).

Even copy that you did not author can affect your business’ credibility. When I’m searching online for accommodation or a pricey gadget, I rely heavily on other customers’ reviews. I’m usually much more likely to trust a well-written review than reviews filled with unqualified hyperboles (“amazing”, “best ever”) or with language errors.

A 2017 study reported by Indiana University supports this, where the researchers note how 2 types of errors affect a reviewer’s credibility. Misspellings, like “lite”, “radicle” or “definately”, are more easily forgivable as “errors of knowledge”, a typical challenge for non-English speakers or artsy creative types.

Conversely, typographical errors, like “wsa” (“was”) and “regualr” (“regular”) are seen as “errors of carelessness”, which more easily erode our confidence in the writer’s authority.

Beyond first impressions, ongoing impressions count, too. A Harvard Business Review article (2013) reported a study where professional success was correlated with language proficiency. For example, “Professionals with fewer grammar errors in their profiles achieved higher positions,” and, “Fewer grammar errors correlate with more promotions.” Further, “Grammar skills may indicate several valuable traits, such as . . . accuracy in their work . . . critical thinking . . . intellectual aptitude.”

Whatever you publish—your website, content marketing, or internal company reports and emails—you want your reader to not just like, but want to, engage with your writing. You want to strengthen trust and credibility.

Ultimately, you want each message to achieve its purpose, like educating a customer and influencing their buying decision.

So does bad grammar cost you? For each error, the context suggests “it depends”. But given enough errors over time, the answer is surely “yes”.

If your copywriting is fraught with errors, how much credibility, influence, or revenue are you losing?