XRF / Assay Total Checker
Sum a major-oxide analysis (plus LOI, H₂O, CO₂ or other reported components) and see how close the analytical total is to 100% — a fast sanity check with a tolerance you set, not a lab QA certification.
Reported components (wt%)
| Include | Component | wt% | |
|---|---|---|---|
A sanity check, not a lab QA certification. The cause of a low or high total is not inferred as fact.
Total & balance
Runs entirely in your browser. Your assay data is not uploaded or stored by Zerdly.
- Enter at least one included component value.
Assumptions & basis
- Scope: A total check, not a laboratory QA certification (derived)
Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- Enter each reported component in wt% and tick the ones to include in the total.
- Optionally set an acceptable ± difference from 100% — you choose it; there is no universal pass/fail.
- Read the analytical total, the difference from 100% and each component's contribution.
How it works
The analytical total is simply the sum of the included components, and the balance is 100 − total. A whole-rock major-oxide analysis with LOI usually lands close to 100%, but small deviations are normal because of unanalysed elements, oxidation-state assumptions and ordinary analytical error.
This is a check, not a laboratory quality certification, so it deliberately does not invent a universal pass/fail tolerance or diagnose the cause of a low or high total. You set the acceptable range; the tool reports the number and lets you decide.
Worked example
A basalt analysis with LOI. Summing SiO₂ 49.20, TiO₂ 1.84, Al₂O₃ 15.74, Fe₂O₃ 10.92, MnO 0.20, MgO 6.73, CaO 9.47, Na₂O 2.91, K₂O 1.10, P₂O₅ 0.35 and LOI 1.20 gives an analytical total of 99.66%, a balance of 0.34% from 100 — comfortably within a ±1% check.
Common mistakes
- Double-counting iron by including both Fe₂O₃ and FeO on inconsistent bases.
- Expecting exactly 100% — real totals scatter around it.
- Reading a low total as a specific fault; this tool flags the size, not the cause.
Frequently asked questions
What total should I expect?
For a complete major-oxide analysis with LOI, roughly 99–101% is common. What is acceptable depends on the material and method, so you set the tolerance.
Why might the total be low?
Unanalysed components, moisture/volatile handling, iron oxidation-state assumptions or analytical error can all shift the total. The tool shows the size of the gap without asserting the cause.
Related tools
- Major Oxide Normalization Calculator
- Loss on Ignition (LOI) Calculator
- Elements to Oxide Calculator
- Total Rare Earth Oxide (TREO) Calculator
- Assay Unit Converter
- Mineral Formula / APFU Calculator
Explore more in Geology, Geotechnical & Ground Engineering.
Cite this tool
Zerdly. (2026). XRF / Assay Total Checker. Retrieved from https://www.zerdly.com/tools/xrf-assay-total-calculator/
Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.