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CGS to SI Units Converter

Science

Convert CGS units to SI units and back — dyne to newton, erg to joule, gauss to tesla, poise to pascal-second, and more physics unit pairs instantly.

Reviewed by the thecalcu.com team · Last updated July 17, 2026

Result (newton (N))
0.00001 newton (N)

CGS ↔ SI Reference Table

What is a CGS ↔ SI?

The CGS to SI Units Converter converts values between the CGS (centimetre-gram-second) and SI (International System of Units) systems across the physical quantities where both systems are still actively used, force, energy, pressure, viscosity, magnetic flux density, magnetic flux, length, and mass. SI is the dominant system in almost all modern science, engineering, and everyday measurement, but CGS units like the dyne, erg, and gauss persist in physics textbooks, electromagnetism, astrophysics, and older published research, making conversion between the two a recurring need for students and researchers.

Because CGS and SI use different base units (centimetres and grams versus metres and kilograms), the conversion factor between corresponding derived units, like dyne and newton, isn't always an obvious round number. This tool handles that calculation directly: pick the physical quantity you're working with, enter a value, and get the converted result immediately. For force-specific conversions using more everyday units like pounds-force, see the Force Converter.

Why Use a CGS to SI Converter?

Physics coursework and research papers frequently mix unit systems, a textbook problem might give a force in dynes while expecting an answer in newtons, or a paper on stellar magnetic fields might report values in gauss that need converting to tesla for a modern calculation. Manually tracking the CGS-to-SI conversion factor for each quantity (they range from 10⁻⁴ for magnetic flux density to 10⁻⁸ for magnetic flux) is easy to get wrong, especially under exam or deadline pressure.

This converter keeps all the relevant quantity pairs in one place with their exact conversion factors, so you don't need to look up or re-derive them each time. If your work also involves general viscosity conversions outside the CGS/SI comparison, the Viscosity Converter covers a broader range of viscosity units.

Who Should Use This Converter?

  • Physics students converting textbook problems between CGS units (dyne, erg, gauss) and SI units for homework or exams.
  • Researchers in electromagnetism and astrophysics working with published literature that reports values in CGS (particularly common for magnetic field strength and stellar energy output).
  • Engineers reviewing older technical documentation or legacy equipment specifications that predate widespread SI adoption.
  • Materials scientists converting viscosity measurements between poise/stokes (CGS) and pascal-second/m²/s (SI) for lab reports or specifications.
  • Educators preparing teaching materials that need to present the same physical quantity in both unit systems for comparison.

What Insights Does the CGS ↔ SI Converter Give You?

Select a Physical Quantity (Force, Energy/Work, Pressure, Dynamic Viscosity, Kinematic Viscosity, Magnetic Flux Density, Magnetic Flux, Length, or Mass) to load the correct CGS/SI unit pair and conversion factor for that quantity. The Result box shows your converted value along with its unit label, so there's no ambiguity about which system the output belongs to.

The CGS ↔ SI Reference Table below the calculator lists every supported quantity pair and its exact conversion factor at a glance, useful as a quick lookup even without entering a specific value, and it doubles as a way to jump directly to a different quantity by clicking any row.

How to use this CGS ↔ SI calculator

  1. Select the Physical Quantity you're converting, for example, "Force".
  2. Enter your value in the Value field, in the unit shown (CGS by default).
  3. Use the ⇅ Swap button if you need to convert from SI back to CGS instead.
  4. Read the converted result in the Result box, labelled with its target unit.
  5. Click the copy button to copy the result for a homework answer, report, or calculation.
  6. Browse the Reference Table to see conversion factors for other quantities without re-entering a value.
Show formula & methodology ↓Show less ↑

Formula & Methodology

Each quantity pair has a fixed multiplier defining how many SI units equal one CGS unit:

- Force: 1 dyne = 1×10⁻⁵ newton
- Energy / Work: 1 erg = 1×10⁻⁷ joule
- Pressure: 1 barye = 0.1 pascal
- Dynamic Viscosity: 1 poise = 0.1 pascal-second
- Kinematic Viscosity: 1 stokes = 1×10⁻⁴ m²/s
- Magnetic Flux Density: 1 gauss = 1×10⁻⁴ tesla
- Magnetic Flux: 1 maxwell = 1×10⁻⁸ weber
- Length: 1 centimetre = 0.01 metre
- Mass: 1 gram = 0.001 kilogram

CGS → SI: Result = Input × factor
SI → CGS: Result = Input ÷ factor

Worked example, converting 500 dyne to newtons:

Result = 500 × 1×10⁻⁵ = 0.005 newtons

This confirms that even a moderately large dyne value converts to a small newton value, since the newton is a much larger unit of force than the dyne.

For a fuller definition, see our glossary entry on CGS.

Frequently Asked Questions

What is the difference between the CGS and SI unit systems?
CGS (centimetre-gram-second) is an older metric system built on centimetres, grams, and seconds as base units, while SI (the International System of Units) is the modern standard built on metres, kilograms, and seconds. SI replaced CGS as the dominant system in most fields during the 20th century, but CGS units like dyne, erg, and gauss still appear in physics textbooks, older research papers, and certain specialised disciplines like electromagnetism and astrophysics.
How do I convert dyne to newton?
Select 'Force' as the quantity, choose the CGS-to-SI direction, and enter your value in dyne, one dyne equals 0.00001 (1×10⁻⁵) newtons. Since a dyne is a very small unit compared to a newton, converted results are typically much smaller numbers.
How do I convert erg to joule?
Select 'Energy / Work' as the quantity and enter your value in erg, one erg equals 0.0000001 (1×10⁻⁷) joules. This reflects how much smaller the CGS energy unit is compared to its SI counterpart.
What is a gauss, and how does it relate to a tesla?
The gauss is the CGS unit of magnetic flux density, still commonly used to describe the strength of small magnets and Earth's magnetic field, while the tesla is the SI unit used in most modern physics and engineering contexts. One gauss equals 0.0001 (1×10⁻⁴) tesla, meaning it takes 10,000 gauss to equal one tesla.
What is poise, and why is it used for viscosity?
Poise is the CGS unit of dynamic viscosity, historically used to describe how thick or resistant to flow a fluid is, water has a viscosity of about 0.01 poise (1 centipoise) at room temperature. The SI equivalent is the pascal-second, and one poise equals 0.1 pascal-seconds.
Why do some fields still use CGS units instead of SI?
Electromagnetism in particular retains CGS units (especially the Gaussian variant) in some academic physics contexts because certain equations take a simpler form in CGS than in SI. Astrophysics and plasma physics also frequently report values in CGS units like erg and gauss due to long-standing convention in published literature.
How do I convert an SI value back to CGS?
Use the ⇅ Swap button to reverse the conversion direction, then enter your SI value (for example, in newtons or joules), the converter divides by the same factor it used to convert from CGS to SI. This gives you the equivalent CGS unit value directly.
What is the difference between poise and stokes?
Poise measures dynamic viscosity (a fluid's resistance to flow under an applied force), while stokes measures kinematic viscosity (dynamic viscosity divided by the fluid's density). Both are CGS units with SI equivalents included in this converter, pascal-second for poise, and square metres per second for stokes.
How small is a dyne compared to a newton?
A dyne is 100,000 times smaller than a newton, it takes 100,000 dynes to equal 1 newton. This is because CGS base units (centimetre, gram) are themselves smaller than SI base units (metre, kilogram), and force scales with both mass and distance in its underlying formula.
Can I convert length and mass with this tool as well as electromagnetic units?
Yes, length (centimetre to metre) and mass (gram to kilogram) are included alongside the derived quantities like force, energy, and magnetic flux density, since CGS and SI share the same fundamental structure across all these quantities. For everyday length or weight conversions outside a physics context, the [Length Converter](/length-converter/) and general unit converters may be more convenient.
Also known as
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