Two-Terminal SMD Land Pattern Calculator

Calculate a first-pass resistor or MLCC footprint from the exact component's body and termination limits: two copper pads, centre pitch, courtyard and solder-mask openings.

Method, formulas and references

How the land is calculated

This is a first-pass, two-terminal chip geometry using the Z/G/X land dimensions described by IPC-7351 and IPC-7352. It is not an IPC-certified footprint or a substitute for an exact part's recommended pattern. Enter minimum and maximum body length L and width W, and each end termination length T from the same datasheet.

The estimated inner termination spacing ranges from Smin = Lmin − 2Tmax to Smax = Lmax − 2Tmin. Independent component limits are combined conservatively. With fabrication allowance F, placement allowance P, and chosen toe, heel and side extensions JT, JH and JS:

Z = Lmin + 2JT + √[(Lmax − Lmin)² + F² + P²]

G = Smax − 2JH − √[(Smax − Smin)² + F² + P²]

X = Wmin + 2JS + √[(Wmax − Wmin)² + F² + P²]

Each copper pad is (Z − G)/2 long and X wide, with centre pitch (Z + G)/2. The courtyard encloses whichever is larger, the maximum body or copper envelope, with the entered excess on each side. Solder-mask openings expand each pad by the entered amount. Paste starts at 1:1 copper; the assembly process may require a different stencil aperture.

These root-sum-square allowances are design assumptions, not universal factory capabilities or joint goals. MLCC stress, tombstoning, solder volume, hand versus reflow assembly, and high-frequency pad discontinuities can change the pattern. Prefer the component manufacturer's recommended land and the assembler's stencil rules when available.

Data sources

IPC-7351, Generic Requirements for Surface Mount Design and Land Pattern Standard
Component geometry, mounting conditions, tolerances and solder joints.
IPC-7352 (2023), Generic Guideline for Land Pattern Design
Component tolerancing, solder-joint analysis and courtyard determination.
Murata, MLCC mounting methods
Land symmetry and solder volume affect mounting reliability.

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