Delta Symbol (Δ δ): Meaning, Uses and Copy Paste

Uppercase / lowercase	Δ / δ
Position in alphabet	4 of 24
Unicode	U+0394 / U+03B4
HTML entity	Δ / δ
HTML decimal	Δ / δ
LaTeX	\Delta / \delta
Word (type code, then Alt+X)	0394 / 03B4
Windows Alt code	Alt + 235 (δ)
Greek numeral value	4

The delta symbol (Δ δ) is the fourth letter of the Greek alphabet, and in math and science it usually means “change.” For example, Δt means a change in time. This guide covers what both forms mean, which lookalikes to avoid and how to type the real letter.

What the Delta Symbol Means

Delta is letter 4 of 24, and it stands for the sound “d.” In the Greek numeral system, it also had the value 4. Capital Δ has a simple triangle shape, which makes it easy to recognize.

The name comes from the Phoenician letter daleth, which meant “door,” according to Britannica. The Greeks renamed it delta but kept the basic shape. Later, Latin turned the triangle into our rounded D. So every capital D you type is a distant cousin of Δ.

In US English, people say “DEL-tuh.” In modern Greek, however, delta sounds like the “th” in “this.” So Greek speakers say its name roughly as “THEL-tah.”

Uppercase vs Lowercase Delta

Capital delta (Δ) is an equal-sided triangle. Lowercase delta (δ) looks like a small circle with a curling stroke on top. Both forms are common, but they mean different things in formulas.

Several math symbols look like delta, so it is easy to grab the wrong one. Here are the main lookalikes:

• ∆ increment (U+2206): a math sign that looks like Δ. Mac users get it with Option+J. Unicode keeps it as a separate character, but most math and Greek text uses U+0394.
• ∂ partial differential (U+2202): a rounded “d” used in calculus. Our partial derivative symbol guide explains it in detail.
• ∇ nabla (U+2207): an upside-down triangle used for the gradient in vector calculus. It is not a Greek letter at all.

Delta in Math, Science and Finance

The capital delta symbol almost always means “change in” a value. Meanwhile, lowercase δ has several more specific meanings. Here is how each field uses them.

Math and Calculus

In algebra, Δx means the change in x, or the final value minus the starting value. So the slope of a line is Δy divided by Δx. Some textbooks also use Δ for the discriminant, b² − 4ac, of a quadratic equation.

In calculus, δ shows up in the epsilon-delta definition of a limit. There, δ is a small distance around a point, paired with ε. Mathematicians also use the Kronecker delta, δᵢⱼ, which equals 1 when i = j and 0 otherwise. For more, see our guide to Greek letters in math.

Physics

Physicists write ΔT for a temperature change and Δv for a change in velocity. Similarly, the Dirac delta, δ(x), models a spike at a single point, like a sudden impulse. Capital Δ can also stand for the Laplace operator in some texts. In engineering, δ often means a small displacement or deflection, such as how far a beam bends under load.

Chemistry

In chemistry, ΔH is the enthalpy change of a reaction, and ΔG is the change in free energy. Also, a Δ written above a reaction arrow means heat is added. Lowercase δ+ and δ− mark partial charges in polar molecules. In NMR spectroscopy, δ is the chemical shift, measured in parts per million (ppm). It tells chemists where each signal sits relative to a reference compound. Our Greek letters in chemistry guide lists more examples.

Finance

In options trading, delta measures how much an option’s price moves when the stock moves by $1. For example, a call with a delta of 0.5 gains about 50 cents per $1 rise. Read more in our option Greeks explainer, along with gamma, which tracks how delta itself changes.

How to Type the Delta Symbol

The simplest way is to copy Δ or δ from the card at the top of this page. Otherwise, use one of these methods. Pay attention to the Mac shortcut, since it gives a lookalike.

• Windows Alt code: hold Alt and type 235 on the numeric keypad for δ. Capital Δ has no Alt code. See the full Greek Alt code list.
• Microsoft Word: type 0394 and press Alt+X for Δ, or 03B4 for δ. This trick is covered in Microsoft support.
• Windows symbol panel: press Win + . (period), go to symbols and open the Greek set.
• Mac: Option+J types ∆, the increment sign, not Greek Δ. For the true letter, press Fn+E and search “delta,” or add a Greek keyboard. Our Mac Greek typing guide shows each step.
• LaTeX: use \Delta for Δ and \delta for δ. Find every command in Greek letters in LaTeX.
• HTML: use Δ or Δ for Δ, and δ or δ for δ.

Delta in Culture and Everyday Use

The river delta got its name from the letter. The Greek historian Herodotus used the word for the triangle-shaped mouth of the Nile. Later, English applied “delta” to any river mouth, whatever its shape.

Delta is also the word for D in the NATO phonetic alphabet, used by pilots and the military. In college life, Delta Sigma Theta was founded at Howard University on January 13, 1913. Explore more names in our guide to fraternity and sorority letters.

In everyday speech, “delta” simply means the difference between two numbers. For instance, a manager might ask for the delta between this year’s sales and last year’s. That use comes straight from the math meaning. Similarly, many reports and spreadsheets label a “change” column with a simple Δ to save space.

Delta Symbol Quick Reference

This table lists every code for both forms of delta. It also shows the increment sign, so you can tell them apart.

Item	Capital Δ	Lowercase δ	Increment ∆
Unicode	U+0394	U+03B4	U+2206
HTML entity	Δ	δ	None
HTML decimal	Δ	δ	∆
Windows Alt code	None	Alt+235	None
Word (Alt+X)	0394	03B4	2206
Mac shortcut	Character Viewer	Character Viewer	Option+J
LaTeX	\Delta	\delta	None
Numeral value	4	4	—

After delta comes epsilon, another favorite of calculus. Visit the epsilon symbol page to see its two shapes, ε and ϵ.

Frequently Asked Questions

What does the delta symbol mean?

Capital delta (Δ) usually means “change in,” so Δx is the change in x. Lowercase delta (δ) often means a very small amount or a specific function. Delta is also the fourth letter of the Greek alphabet.

How do I type the delta symbol on Windows?

Hold Alt and type 235 on the numeric keypad to get lowercase δ. Capital Δ has no Alt code, so type 0394 in Word and press Alt+X. You can also use the Win + . symbol panel.

How do I type Δ on a Mac?

Option+J types ∆, which is the increment sign (U+2206), not Greek capital delta. For the true Δ (U+0394), open the Character Viewer with Fn+E and search “delta.” A Greek keyboard also works.

Is the delta symbol the same as the partial derivative symbol?

No. The partial derivative symbol is ∂ (U+2202), a rounded d used in calculus. Lowercase delta is δ (U+03B4). They look similar but have different meanings and codes.

What does Δ mean in chemistry?

In chemistry, Δ means a change in a quantity, as in ΔH for enthalpy change. Over a reaction arrow, Δ also means heat is applied. Lowercase δ+ and δ− show partial charges on atoms.