Free screening tools for magnet-sensor integration. Estimate field strength at your air gap, compare material demagnetization curves, and check sensor margin before committing to samples.
Estimate the on-axis magnetic field at a given distance from a cylindrical magnet. Adjust diameter, length, material grade, and air gap to see the estimated field strength and margin over your sensor threshold. Results include temperature derating at 85°C.
Typical BOP 3–8 mT
Field at sensor (25°C)
175.3 mT
Field at sensor (85°C)
156.0 mT
Margin over threshold (25°C)
35.1x
Margin at 85°C
31.2x
Good margin
Recommended minimum: 2.0x for industrial, 3.0x for automotive/safety
⚠ Screening estimate only
This calculator uses a simplified axial dipole model for cylindrical magnets. Actual field depends on magnetization uniformity, nearby steel, housing materials, and assembly tolerances. Always validate with gaussmeter measurement on the final assembly.
Second-quadrant B-H curves for NdFeB (N42), SmCo (2:17), and Ferrite (Y30). Hover over each material to highlight its curve and view key specifications. The dashed line shows a typical operating point at −10 kOe.
Higher Br (Y-axis intercept) means stronger surface field. Wider curve (further left on X-axis) means higher coercivity and better resistance to demagnetization. SmCo's curve extends much further left than NdFeB, showing its superior thermal and demagnetization stability.
At elevated temperatures, both Br and Hci decrease. The B-H curve shrinks inward. If the operating point crosses the “knee” of the curve, the magnet suffers irreversible demagnetization. This is why high-temperature grades (SH, UH, EH) have higher Hci.
For a comprehensive comparison of NdFeB, SmCo, AlNiCo, and Ferrite properties, temperature limits, and cost trade-offs, see our Material Selection Guide.
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