Lifetime or Life Time: Which Spelling Is Correct

“Lifetime” and “life time” both appear in print, yet only one is accepted in every major dictionary and style guide. Knowing the difference protects your credibility, sharpens your prose, and keeps editors happy.

Below you’ll find the full story: etymology, usage data, regional quirks, SEO tactics, and real-world editing decisions. Skim once, reference forever.

Why One Spelling Dominates Every Dictionary

Merriam-Webster, Oxford, Collins, and American Heritage all list “lifetime” as a closed compound with no space or hyphen. “Life time” is either omitted or tagged “archaic,” which signals to readers that you’re either quoting 18th-century prose or making an error.

Google’s Ngram Viewer shows the closed form overtaking the open form around 1910 and never looking back. Corpus linguists credit the shift to the same pressure that fused “today,” “tomorrow,” and “cannot”: faster printing, telegraph fees, and the human preference for shorter chunks.

The Etymology That Predicted the Merger

Old English used two separate words: līf (existence) and tīma (period). Middle English scribes began hyphenating when the concept was treated as a unit, as in “life-time of a tree.” By Early Modern English the hyphen had become optional, and Victorian compositors finally closed the gap to save line space.

When Style Guides Override Dictionaries

AP, Chicago, and APA all default to “lifetime,” but each adds a twist you can exploit. AP permits the open form only in direct quotations, Chicago allows “life-time” in historical contexts if you add a sic note, and APA treats the open spelling as a “stylistic deviation” that must be flagged in copy-editing comments.

If you’re writing for a legal publisher, check the house style before you hit submit. Supreme Court briefs follow Black’s Law Dictionary, which lists “lifetime” yet keeps “life-time” in archaic citations, so a single memo can contain both spellings without penalty if you signal the shift.

Regional Variations Nobody Mentions

American editors enforce the closed form with near-religious zeal. British newsrooms are slightly looser: The Times of London accepts “life-time” in headlines when the line break is cleaner, though the body copy still uses “lifetime.”

Australian courts prefer “lifetime” in statutes but retain “life time” in early-case quotations to preserve original transcription. Canadian French-influenced writers occasionally insert a hyphen under the mistaken belief that English compounds mirror French “temps de vie,” a habit editors now stamp out with autocorrect rules.

How to Set Region-Specific Autocorrect in Microsoft Word

Open File → Options → Proofing → Custom Dictionaries → select your region’s .dic file. Add “lifetime” and set the replacement text to flag “life time” as an error. Save the change to your roaming profile so the rule follows you to every workstation.

SEO Impact: Split Traffic Costs You Clicks

Google’s keyword planner treats “lifetime” and “life time” as separate entities, but the open variant draws only 8% of the volume. If you split your usage, you cannibalize anchor text and dilute backlink equity.

Run a quick site:yourdomain.com search paired with each spelling. If both appear, pick the dominant form and 301 redirect the weaker URLs to the stronger ones. Add the canonical tag immediately; you’ll often recover 5–7% organic traffic within one crawl cycle.

Schema Markup That Rewards Consistency

Use “lifetime” in Product structured data for warranty fields. Google’s Rich Results Test throws warnings when the open form appears, because the parser keys on the closed compound to match merchant-center feeds.

Grammar Traps: Possessives, Plurals, and Compounds

Possessive: “The smartphone’s lifetime value” never needs an apostrophe on “lifetime” itself; the genitive attaches to the noun that owns the span. Plural: “Three lifetimes of experience” doubles the “f” before the “s,” avoiding the false friend “lifetimes.”

Compound modifiers: “lifetime-guaranteed battery” keeps the hyphen only when the phrase precedes the noun. Write “battery with lifetime guarantee” when it follows, and never hyphenate the adverbial form “guaranteed for life time”—because that string is simply wrong.

Corporate Branding: Trademarks That Break the Rule

Life Time, Inc. owns the fitness chain “Life Time” and holds a registered trademark with the space intact. In editorial coverage you must reproduce the mark exactly, even if your style sheet bans the open form everywhere else.

The workaround is to add a trademark symbol on first mention, then revert to your house style for generic references. Example: “She joined Life Time® in Texas, but the lifetime membership model is common across gyms.”

How to Code a Disclaimer That Satisfies Legal

Wrap the brand name in a tag and append a CSS pseudo-element that injects the ® symbol. This keeps your style sheet clean while satisfying the trademark-compliance team.

Editing in Practice: Find-and-Replace Recipes

Open your manuscript with a case-sensitive search for “life time” and “life-time.” Replace each hit with “lifetime,” but first toggle “Whole Words Only” to avoid mangling “lifetime supply.”

Next run a wildcard search for “life[ ]time” with two spaces—journalists often double-space after hurried interviews. Add a red-font highlight style before you accept all changes so you can scan for context overrides such as direct quotes or trademarked phrases.

Regex for Clean-Up in VS Code

Press Ctrl+H → toggle regex → search pattern: blife[ -]timeb. Replace with: lifetime. Add the “i” flag for case-insensitive matching, then save the macro to your snippets library for one-click cleanup on every article.

Translation Memory: Why Localization Teams Care

Most CAT tools segment on spaces; “life time” splits into two separate tokens and creates translation duplicates. This inflates word counts and raises client costs, so localization engineers pre-process files to fuse the compound before translators touch them.

SDL Trados users can add “lifetime” to the variable list and set a segmentation rule that auto-joins the open form. The result is a 3–4% drop in weighted words, which on a 100,000-word project saves roughly $400 at standard per-word rates.

Speech-to-Text Failures You Can Prevent

Dragon NaturallySpeaking defaults to the open form when the user pauses between “life” and “time.” Train the engine by voice-selecting the error, saying “correct that,” then spelling “l-i-f-e-t-i-m-e” aloud twice. The software writes the change to your user profile and applies it across all applications.

Zoom’s live transcript engine still outputs “life time” in 2024 builds. If you publish webinar transcripts, batch-replace before upload or you’ll embed the mistake in YouTube captions, where it becomes indexed and harder to purge.

Accessibility: Screen Readers and Compound Words

NVDA pronounces “lifetime” as a smooth two-beat word. Insert a space and the synthesizer adds a glottal stop, forcing visually impaired users to parse an unintended break. The distraction is minor in short articles, but in financial disclosures the stutter can confuse context and breach WCAG 2.2 clarity guidelines.

Test your page with NVDA’s speech viewer; if you hear “life—time,” correct the source immediately. The same check catches hyphen anomalies that also trip audio parsers.

Data-Driven A/B Test: Headlines That Convert

A SaaS blog ran two Google Ads headlines for the same white paper: “Download Our Lifetime Value Calculator” versus “Download Our Life Time Value Calculator.” The closed form lifted CTR by 12.4% and cut bounce rate by 6%, because users subconsciously trust familiar spelling patterns.

Repeat the test on meta descriptions and email subject lines; the delta narrows but still favors the closed form. Archive the losing variant in Search Console so Google doesn’t re-index the outdated snippet.

Tool Stack for Rapid Testing

Use Google Optimize for on-page tests, keeping the variant weight at 50/50. Export results to Sheets, then run a chi-squared test; p < 0.05 usually arrives within 48 hours when traffic exceeds 5,000 impressions.

Academic Citations: MLA, APA, and Chicago Footnotes

MLA 9 tacitly follows Merriam-Webster, so “lifetime” appears even when the cited source uses “life-time.” APA 7 adds an explicit note in §5.11: reproduce the author’s original spelling only for direct quotations, otherwise normalize to “lifetime.”

Chicago 17 allows either approach but recommends a consistency footnote if you mix spellings within the same manuscript. JSTOR’s citation exporter already normalizes to “lifetime,” so importing metadata saves you a manual step.

Common Collocations and Idioms

“Once in a lifetime” never splits, and inserting a space creates an instant shibboleth that copyeditors spot across a crowded page. “Lifetime achievement award” follows the same rule; the open form would disqualify a submission from the Emmys’ official ballot.

Tech marketing coined “lifetime deal” and “lifetime license” during the 2010 AppSumo boom; both stick to the closed form. The rare exception is legal boilerplate that quotes 19th-century statutes, where “for the life time of the patent” surfaces as a deliberate archaism.

The Final Editorial Checklist

Run spell-check, regex, and trademark review in that order. Lock the preferred form in your style sheet, then distribute the updated .dotx template to every freelancer. Add a linter rule to your GitHub repo so pull requests fail on “life time,” forcing authors to fix the error before merge.

Archive a changelog entry; spelling consistency is a silent ranking factor that compounds over years. When the next writer asks which version is correct, point them to the checklist and close the ticket—no debate required.