Curie's Law states that the magnetic susceptibility of a paramagnetic material is inversely proportional to its absolute temperature: χ = C/T. It was discovered by Pierre Curie in 1895.

When should I use the Curie–Weiss Law instead?

Use the Curie–Weiss Law for real ferromagnetic materials above their Curie temperature, where exchange interactions shift the susceptibility. The Curie–Weiss law is χ = C/(T−Tc) and reduces to Curie's law when Tc = 0.

What is the Curie temperature?

The Curie temperature (Tc) is the critical temperature above which a ferromagnet loses its spontaneous magnetization and becomes paramagnetic. Iron has Tc = 1043 K, nickel 631 K, and cobalt 1394 K.

Why does susceptibility diverge at Tc?

At T = Tc, the denominator (T − Tc) = 0, causing χ → ∞. This mathematically represents the phase transition to ferromagnetic order. In reality, the transition is slightly smoothed by fluctuations.

Can susceptibility be negative?

In diamagnetic materials, χ is negative (typically ~10⁻⁵). Curie's Law applies only to paramagnets with positive χ. Diamagnetism is temperature-independent and not described by Curie's Law.

How do I find the Curie constant experimentally?

Plot 1/χ vs T for paramagnetic data. The slope is 1/C (the reciprocal of the Curie constant). The x-intercept gives the Curie temperature Tc for Curie–Weiss behavior.

Curie's Law Calculator

Calculate magnetic susceptibility using Curie's Law and the Curie–Weiss Law for paramagnetic and ferromagnetic materials at any temperature.

Law

Curie Constant C (K)

Curie Temperature Tc (K)

Temperature T (K)

Applied Field H (A/m)

Table Points

Susceptibility (χ)

0.026316

Curie–Weiss: C/(T−Tc), T/Tc = 1.055

Magnetization (M)

2,631.58 A/m

M = χ × H

B-field

0.128971 T

B = μ₀(H + M)

Relative Permeability (μr)

1.0263

μr = 1 + χ

1/χ

38.0000

Inverse susceptibility—linear with T for paramagnets

Magnetic Regime

Paramagnetic

T = 1100 K, Tc = 1043 K

Temperature Scale

0 K

2Tc

FerromagneticTcParamagnetic

χ vs Temperature

T (K)	T/Tc	χ	M (A/m)	Regime
522	0.50	∞	∞	Ferromagnetic
894	0.86	∞	∞	Ferromagnetic
1,267	1.21	0.006711	671.14	Paramagnetic
1,639	1.57	0.002517	251.68	Paramagnetic
2,012	1.93	0.001549	154.88	Paramagnetic
2,384	2.29	0.001119	111.86	Paramagnetic
2,757	2.64	0.000875	87.54	Paramagnetic
3,129	3.00	0.000719	71.91	Paramagnetic

Susceptibility Comparison

1,267 K

1,639 K

2,012 K

2,384 K

2,757 K

3,129 K

Planning notes, formulas, and examples

About the Curie's Law Calculator

Curie's Law describes how the magnetic susceptibility of paramagnetic materials varies inversely with temperature: χ = C/T, where C is the Curie constant. This simple relationship explains why paramagnets become more responsive to magnetic fields at lower temperatures, as thermal agitation decreases and atomic magnetic moments align more readily with the external field.

The Curie–Weiss Law extends this by incorporating interactions between magnetic moments: χ = C/(T − Tc), where Tc is the Curie temperature. Above Tc, the material behaves paramagnetically. At Tc, susceptibility diverges, signaling the phase transition to ferromagnetic order where spontaneous magnetization appears without an external field.

This calculator implements both Curie's Law and the Curie–Weiss modification, allowing you to compute susceptibility, magnetization, B-field, and relative permeability at any temperature. It generates temperature-dependent susceptibility tables and visual phase diagrams showing the transition between paramagnetic and ferromagnetic regimes.

When This Page Helps

Curie's Law is a cornerstone of magnetism in physics and materials science. This calculator makes it easy to explore temperature-dependent magnetic behavior for research, coursework, and materials characterization without tedious manual calculations.

How to Use the Inputs

Choose between Curie's Law (ideal paramagnets) or Curie–Weiss Law (real materials with interactions).
Enter the Curie constant C for your material (determines overall susceptibility magnitude).
Input the Curie temperature Tc in Kelvin (the ferromagnetic–paramagnetic transition point).
Set the working temperature T to calculate susceptibility at that specific point.
Enter the applied magnetic field strength H in A/m.
Adjust the number of table points to generate a detailed temperature sweep.
Review the susceptibility chart and regime classification.

Formula used

Curie's Law: χ = C / T
Curie–Weiss Law: χ = C / (T − Tc)
Magnetization: M = χ × H
B-field: B = μ₀(H + M)
Relative permeability: μr = 1 + χ
Where C = Curie constant, T = temperature, Tc = Curie temperature, H = applied field.

Example Calculation

Result: χ ≈ 0.0263, M ≈ 2632 A/m

Using the Curie–Weiss law with C = 1.5 and Tc = 1043 K at T = 1100 K (57 K above Tc), the susceptibility is about 0.0263 and the magnetization in a 100,000 A/m field is approximately 2632 A/m.

Tips & Best Practices

Plot inverse susceptibility (1/χ) vs temperature for a straight line—the slope gives 1/C.
A negative Curie temperature indicates antiferromagnetic interactions.
The Curie–Weiss law is only valid well above Tc; near Tc, critical fluctuations cause deviations.
For polycrystalline samples, the measured susceptibility is an average over crystal orientations.
Use SI units consistently—H in A/m, M in A/m, B in Tesla.

When To Use This Calculator

Calculate magnetic susceptibility using Curie's Law and the Curie–Weiss Law for paramagnetic and ferromagnetic materials at any temperature. Use it when you need a repeatable calculation in the physics / general category and want the setup, result, and supporting values kept together. This is especially helpful when small input changes, unit choices, or rounding decisions can change the final number.

How To Check The Result

Start by confirming that the inputs match the formula shown on the page. Then compare the main output with the worked example and any secondary values shown by the calculator. If the result will be used in another calculation, keep extra precision until the final step and record the assumptions beside the number.

Practical Notes

Treat the result as a calculation aid rather than a substitute for context. For schoolwork, include the formula and substitution steps. For planning, technical, financial, or health-related decisions, verify important numbers against primary records, current rules, or a qualified professional before acting on them.

Sources & Methodology

Last updated: January 15, 2025

Frequently Asked Questions

Curie's Law states that the magnetic susceptibility of a paramagnetic material is inversely proportional to its absolute temperature: χ = C/T. It was discovered by Pierre Curie in 1895.