Mathematics: +- - ±

Typing "+-" or "+/-" when you mean the single symbol "±" is common. Use "±" in formal math and science, use "+/-" as a plain-text fallback, and avoid "+-" (plus directly followed by a hyphen) because it's ambiguous and often misrenders.

Below are clear rules, focused examples for work, school, and casual writing, quick fixes you can copy, and memory tricks to stop the habit.

Quick answer

Use "±" for "plus or minus." Use "+/-" only when you cannot insert the ± glyph. Never use "+-".

• "±" is one glyph meaning "plus or minus" and behaves consistently across lines and fonts.
• "+/-" is an acceptable plain-text fallback; keep the slash next to the signs (no spaces) when writing measurements inline.
• "+-" mixes the plus sign and a hyphen/minus and can look like a typo or break formatting.

Core explanation

"±" denotes two possible values: one with a plus and one with a minus. Writing two separate characters ("+-") fails to convey that unity and can confuse readers or software that expects a single symbol.

Technically, "+" plus "-" are distinct code points. "±" is U+00B1. Relying on separate characters can cause wrapping issues, poor alignment in tables, and awkward OCR results.

Spacing and hyphenation

Keep the symbol snug to the numbers. For inline numeric notation prefer "0.5 ± 0.1" or "0.5±0.1" depending on your style guide; as a plain-text fallback use "0.5+/-0.1".

• Good plain-text fallback: "±" → "0.5+/-0.1" (no spaces around the slash).
• Avoid: "0.5 +- 0.1" (looks like two operators and may confuse readers or parsers).
• In prose, consider writing words: "about 0.5, plus or minus 0.1."

Grammar and when to use words instead

For non-technical audiences, rewrite numeric ± expressions into words. That improves clarity when readers might not parse symbols quickly.

• Technical audience: "The current is 5 ± 0.2 A."
• General audience: "The current is about 5 amps, plus or minus 0.2."
• If a sentence reads awkwardly with a symbol, rewrite the whole clause rather than forcing the glyph in.

Real usage: examples to copy

These wrong/right pairs show typical contexts and are ready to paste.

• Math (quadratic): Wrong: x = -(b +- √(b² - 4ac)) / (2a).
  Right: x = -(b ± √(b² - 4ac)) / (2a).
• Work (tolerance): Wrong: The tolerance is 0.5+-0.1 mm.
  Right: The tolerance is 0.5 ± 0.1 mm.
• School (grade range): Wrong: The score is 85+/-5%.
  Right: The score is 85 ± 5%.
• Casual (time estimate): Wrong: I'll be there in 20+-5 minutes.
  Right: I'll be there in 20 ± 5 minutes. Or: I'll be there in about 20 minutes, give or take 5.
• Work (budget): Wrong: Budget estimate: $10,000+-$500.
  Right: Budget estimate: $10,000 ± $500.
• School (measurement lab): Wrong: Length = 12.3+-0.2 cm.
  Right: Length = 12.3 ± 0.2 cm.

Work, school, and casual examples (more)

Three quick contexts with more variants you'll commonly edit.

• Work
  • Wrong: The machine uses 220+-10 V.
    Right: The machine uses 220 ± 10 V.
  • Wrong: Delivery in 3+-1 days.
    Right: Delivery in 3 ± 1 days.
  • Wrong: Expect 2+-0.5% variance.
    Right: Expect 2 ± 0.5% variance.
• School
  • Wrong: Voltage measured at 4.7+-0.1 V.
    Right: Voltage measured at 4.7 ± 0.1 V.
  • Wrong: x = 7+-2 is the solution set.
    Right: x = 7 ± 2 is the solution set.
  • Wrong: The sample mass is 50+-3 g.
    Right: The sample mass is 50 ± 3 g.
• Casual
  • Wrong: The hike is 8+-1 miles.
    Right: The hike is 8 ± 1 miles.
  • Wrong: Bake 30+-2 minutes.
    Right: Bake 30 ± 2 minutes (or "about 30 minutes, plus or minus 2").
  • Wrong: The score was 14+-3.
    Right: The score was 14 ± 3.

Try your own sentence

Paste the sentence into an editor, replace "+-" or "+/-" with "±" when values are numeric, or rewrite in words for general prose.

How to fix your own sentence

Quick three-step fix: identify the numeric expression, choose the right symbol or words, then read the full sentence for flow.

• Step 1: Is the context technical? If yes, use "±".
• Step 2: If you can't type "±", use "+/-" as a fallback, keeping the slash tight to the signs (no spaces).
• Step 3: For a general audience, write "plus or minus" or "about ... give or take ...".

• Rewrite example 1: Original: Shipping time is 7+-2 days.
  Rewrite: Shipping time is 7 ± 2 days. Or: Shipping time is about 7 days, give or take 2.
• Rewrite example 2: Original: The reading is 1.25+-0.05 A.
  Rewrite: The reading is 1.25 ± 0.05 A.
• Rewrite example 3: Original: Our margin is 15+/-3%.
  Rewrite: Our margin is 15 ± 3%.

A simple memory trick

Think of "±" as a single button marked "either + or -." Visualizing one key instead of two signs helps you avoid typing them separately.

• Train by doing a global find for "+-" and "+/-" in your drafts and replacing with "±" or a worded phrase.
• When you edit numbers, scan for adjacent operator characters and correct them in one pass.

Similar mistakes to watch for

Fixing ± is a good cue to check for other small symbol and spacing errors that affect clarity.

• Misplaced hyphens: e.g., "re-create" vs "recreate" depending on meaning.
• Wrong minus vs en-dash: using a hyphen for ranges instead of an en-dash in formatted text.
• Loose spacing around units: "5kg" vs "5 kg" (follow your style guide).
• Mixing symbols and words awkwardly in prose: prefer "plus or minus" in nontechnical writing.

FAQ

Is "+-" the same as "±"?

No. "+-" are two characters and can be misread or misformatted. "±" is the proper single symbol. Use "+/-" only when you cannot insert the glyph.

Can I use "+/-" in a journal or thesis?

Journals and theses typically require the actual "±" glyph in final submissions. Use "+/-" only in plain-text drafts; replace it with "±" before submitting.

How do I type "±" across devices?

Windows: Alt+0177 on the numeric keypad or insert symbol; Mac: Option+Shift+= (varies by layout); HTML: ± or U+00B1; LaTeX: \pm. If none of these are available, use "+/-" as a fallback.

When should I rewrite "±" as words?

Rewrite for nontechnical readers, UX copy, or where a sentence flows better with words. For example, "about 10, plus or minus 2" reads clearer than "10 ± 2" in casual text.

Why does "+-" sometimes break formatting or wrap badly?

Because "+-" is two characters and may be treated separately by line-breaking and fonts. The single "±" glyph avoids those wrapping and spacing issues.

Final check

Do a final pass: find "+-" and "+/-", replace with "±" or "plus or minus" as appropriate, and scan nearby paragraphs for related spacing or hyphenation errors. Small cleanups make numbers and meaning much clearer.