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Weighted Average Drill Intercept Grade Calculator

Calculate a length-weighted average assay grade by multiplying every included grade by its sampled interval length, summing those grade-length products, and dividing by total included sampled length. This avoids the distortion of a simple mean when sample lengths differ. Enter from depth, to depth, and grade for two to fifty drill-core, reverse-circulation, trench, or channel intervals. GeoMiner sorts the intervals, rejects overlaps that would double count length, reports each interval's weight, and exposes unsampled gap length separately. Gaps are excluded rather than silently assigned zero grade. Every row must use one analyte, chemical basis, grade unit, depth datum, and measurement system. Preserve laboratory qualifiers and decide how missing core, unassayed material, internal waste, below-detection results, duplicates, over-range assays, cutoffs, minimum width, dilution, and capping are treated before a composite is reported. The span is measured along the entered axis. A downhole interval is not automatically true thickness; orientation and geometry require separate evidence or a clear qualification. The calculator applies no density, support correction, spatial weighting, declustering, recovery, dilution, capping, cutoff, metal-equivalent, contained-metal, resource, reserve, ownership, or economic interpretation. A weighted composite does not prove representativeness, continuity, unbiased sampling, QA/QC acceptance, geological significance, resource confidence, reserve status, or value. Public and consequential reporting requires balanced context, the selected aggregation method and assumptions, applicable standards, supporting data and diagrams, uncertainty, and qualified professional review. Values remain in the browser. Analytics retain only bounded action, grade-unit, interval-count range, and gap-status categories—never depths, lengths, grades, analytes, holes, samples, assays, locations, projects, cutoffs, values, or notes.

Verification resources

Cross-check terminology, classification, methods, and safety with these authoritative external resources.

  • undefined. Tabulates weighted average as the sum of grade-times-core-sample-length divided by summed sample length.
  • undefined. Describes calculating block grade by weighting assay grades by sample lengths and discusses cutoffs and interbedded low-grade material.
  • undefined. Explains why missing-core intervals should be recorded so missing data are not mistaken for a continuous record.
  • undefined. Calls for balanced reporting, sample intervals, clear weighted-average methods, and a true-width qualification when true width is not reported.
  • undefined. Separates arithmetic exploration results from the geological evidence and professional work required for resource and reserve classification.

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Common questions

How do I calculate a length-weighted average drill-intercept grade?
Multiply each assay grade by its sampled interval length, add the products, and divide by the sum of included sampled lengths.
Why not take a simple average of assay grades?
A simple mean gives unequal-length samples equal influence. Length weighting gives each included sample influence proportional to its interval length.
Are gaps included as zero grade?
No. GeoMiner exposes unsampled length separately and does not silently assign a value to missing or excluded material.
Is a downhole intercept the true thickness?
Not necessarily. Downhole length equals true thickness only under a specific geometric relationship, so true width needs separate orientation evidence or a clear qualification.
Does a weighted average establish a resource or reserve?
No. It is arithmetic over selected inputs and does not establish continuity, representativeness, resource confidence, modifying factors, reserve status, value, or compliant disclosure.

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