Constants List

How to Use the Constants List

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   Switch between Physics, Chemistry, Math, Engineering, or view all constants.

2. Search Instantly

   Type in the search box to filter constants by name, symbol, or value in real time.

3. Copy with One Click

   Click the copy icon next to any value to copy it to your clipboard instantly, ready for use in calculations, code, or reports.

Why Use an Online Constants List?

• Instant Access: No more searching textbooks or Wikipedia for common constants.
• Always Up-to-Date: All values sourced from the latest CODATA, IUPAC, and NIST standards.
• Copy-Friendly: One-click copy for every value—no more typos or mistakes.
• SEO & AI Ready: Optimized for Google, Bing, and AI-powered search engines.

Advantages and Limitations

• ✔ 100% Free: No sign-up, no paywall, no ads.
• ✔ Multi-Category: Physics, Chemistry, Math, and Engineering in one place.
• ✔ Real-Time Search: Instantly filter all constants as you type.
• ✔ Copy to Clipboard: Save time and avoid mistakes with one-click copy.
• ✔ Mobile & Desktop Friendly: Use it anywhere, anytime.

• ✘ No Custom Constants: Can’t add your own values (yet).
• ✘ No Unit Conversion: Only standard constants, not a unit converter.
• ✘ No Full References: For full scientific references, check CODATA/IUPAC/NIST.

The Unchanging Pillars of Science: An Ultimate Guide to Physical and Mathematical Constants

In the ever-evolving landscape of science, some things remain steadfast. Physical and mathematical constants are the bedrock upon which our understanding of the universe is built. These are universal values, believed to be the same everywhere and at all times, that quantify the fundamental properties of nature. From the speed of light to the charge of an electron, this Constants List provides a gateway to the numbers that define reality. An online, searchable Constants List is an indispensable tool for students, researchers, and professionals who need these critical values at their fingertips.

This guide will explore the profound significance of these constants, differentiate between the types, and delve into the most important examples from physics, chemistry, and mathematics. We’ll uncover why their precise measurement is a monumental task and how they form the language of the cosmos.

What is a Physical Constant? The Architecture of the Universe

A physical constant is a physical quantity that is universal in nature and has a constant value in time. Unlike a mathematical constant, a physical constant is discovered through empirical measurement. Its value is not derived from pure mathematics but is instead a fundamental feature of the physical world. These constants are the “settings” of our universe; if they were even slightly different, the universe as we know it—from the structure of atoms to the formation of stars—could not exist.

The quest to measure these values with ever-increasing precision has driven much of scientific and technological progress. Organizations like the National Institute of Standards and Technology (NIST) and the Committee on Data for Science and Technology (CODATA) are dedicated to evaluating all available data to provide the world with the most accurate, internationally accepted values for these constants.

Key Categories of Constants

Our Constants List is organized into several key areas of science and engineering, each with its own set of foundational numbers.

1. Universal Constants in Physics

These are the titans of the constants world, appearing in the most fundamental equations of physics that describe space, time, matter, and energy.

• Speed of Light in Vacuum (c): Perhaps the most famous constant, c = 299,792,458 m/s. It is the absolute speed limit of the universe for all forms of energy and information. It’s so fundamental that the meter itself is now defined based on this exact value. It’s the star of Einstein’s equation, E=mc², linking mass and energy.
• Planck’s Constant (h): h ≈ 6.626 x 10⁻³⁴ J·s. This constant is the cornerstone of quantum mechanics. It defines the relationship between the energy of a photon and the frequency of its electromagnetic wave. It represents the smallest possible “packet” or quantum of energy, revealing that the universe is granular at its most fundamental level.
• Gravitational Constant (G): G ≈ 6.674 x 10⁻¹¹ m³·kg⁻¹·s⁻². Featured in Newton’s Law of Universal Gravitation, G determines the strength of the gravitational force between two objects. It’s notoriously difficult to measure with high precision, but its value governs the orbits of planets, the formation of galaxies, and the very structure of the cosmos.
• Elementary Charge (e): e ≈ 1.602 x 10⁻¹⁹ C. This is the fundamental unit of electric charge, the magnitude of the charge of a single proton or electron. It’s the basis of all electrical and electromagnetic phenomena.

2. Foundational Constants in Chemistry

While chemistry uses many of the same physical constants, some are particularly central to its domain of atoms and molecules.

• Avogadro’s Number (Nₐ): Nₐ ≈ 6.022 x 10²³ mol⁻¹. This colossal number is the bridge between the microscopic world of atoms and the macroscopic world we can measure. It defines the number of constituent particles (atoms or molecules) in one mole of a substance. It’s essential for stoichiometry and understanding chemical reactions.
• Gas Constant (R): R ≈ 8.314 J·mol⁻¹·K⁻¹. Also known as the ideal gas constant, R is a key component of the ideal gas law (PV = nRT). It relates the energy, temperature, and amount of a gas, making it fundamental to thermodynamics and physical chemistry.
• Faraday Constant (F): F ≈ 96,485 C·mol⁻¹. Crucial in electrochemistry, the Faraday constant represents the total electric charge carried by one mole of electrons. It’s used to calculate the amount of substance produced during an electrolysis reaction.

3. Abstract Constants in Mathematics

Unlike physical constants, mathematical constants are not measured but are derived from mathematical definitions. They are pure numbers, independent of any physical units. Our Constants List includes the most important of these.

• Pi (π): π ≈ 3.14159.... Defined as the ratio of a circle’s circumference to its diameter, Pi is an irrational number that appears in countless formulas in geometry, trigonometry, and calculus. It is woven into the very fabric of space and cyclical phenomena.
• Euler’s Number (e): e ≈ 2.71828.... This is the base of the natural logarithm. It is the limit of (1 + 1/n)ⁿ as n approaches infinity. It appears naturally in any context involving growth or decay, such as compound interest, population growth, and radioactive decay.
• The Golden Ratio (φ): φ ≈ 1.61803.... An irrational number found in geometry, art, architecture, and nature. It is often cited as a key to aesthetic beauty and appears in the Fibonacci sequence.

The Role of Constants in Engineering

Engineers use a blend of fundamental physical constants and practical, defined values to design and build the world around us. A comprehensive Constants List is a vital part of any engineer’s toolkit.

• Standard Acceleration of Gravity (g₀): g₀ = 9.80665 m/s². While the true gravitational acceleration varies slightly across the Earth’s surface, engineers use this standard defined value for consistent calculations in fields like civil and mechanical engineering.
• Standard Atmosphere (atm): atm = 101,325 Pa. This defined value represents the average atmospheric pressure at sea level and serves as a standard unit for pressure measurements in fluid dynamics and aerospace engineering.

The Pursuit of Precision and the Redefinition of the SI System

The values in any reliable Constants List are not static guesses; they are the result of centuries of meticulous experimentation. In a historic move in 2019, the General Conference on Weights and Measures took a revolutionary step. Instead of defining units like the kilogram based on a physical object, the scientific community chose to define the units based on the exact values of fundamental constants.

For example, Planck’s constant (h) and the elementary charge (e) are now defined to have exact, unchanging values. The kilogram, the ampere, and other SI base units are now derived from these perfect, universal constants. This means that our system of measurement is no longer tied to a decaying artifact in a vault in France but is based on the immutable laws of the universe itself—a truly profound shift in scientific history.

Conclusion: Your Indispensable Scientific Reference

The constants of nature are the silent architects of our universe, governing everything from the smallest quantum interactions to the grandest cosmic structures. They provide a universal language that allows scientists and engineers across the globe to communicate and build upon each other’s work. Having a quick, reliable, and searchable Constants List is more than a convenience; it’s a gateway to performing accurate calculations, writing precise code, and conducting meaningful research. Our free online tool is designed to be that essential resource. It puts the fundamental numbers of the universe at your command, ensuring you have the accurate data you need, whenever you need it. Bookmark this page and make it your trusted companion for all your scientific and technical endeavors.

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