A weight table is part of your formula result
Explain why identical element counts can yield different declared mass totals and how to carry the weight source, exact arithmetic and physical limits into a handoff.
The same counts can have several justified declared totals
The original question supplies C12.01/H1.008/O16 in prose but different C12.0107/H1.00794/O15.9994 values in its code. Treating those as one table would hide the reason the totals differ. The formula counts do not change: C7/H19/O5.
| Declared source | C / H / O | Exact numerical total |
|---|---|---|
| Question prose | 12.01 / 1.008 / 16 | 183.222 |
| Question code | 12.0107 / 1.00794 / 15.9994 | 183.22276 |
| Fixed molmass2026.8.15 literals | 12.01074 / 1.007941 / 15.999405 | 183.223084 |
Arithmetic precision does not create physical precision
The tool multiplies exact integer counts by explicitly declared finite decimal values and aligns decimal scales with integer arithmetic. Every calculated contribution and total is an exact string for that chosen table. It does not infer how precise the underlying physical values are.
Average atomic weights vary with sample composition; table values for unstable elements do not define one universal natural average. The report uses the dimensionless declared atomic-weight sum, numerically a molar mass under the usual g/mol convention. It does not infer physical uncertainty, isotopic exact mass, an isotope spectrum, purity or reaction occurrence.
- Retain the table version or the complete custom CSV with the formula result.
- Separate integer formula counts from the chosen weights and physical interpretation.
- Use Custom explicitly for another declared table; missing weights are a refusal, not an invitation to guess.
A reproducible handoff includes originals and complete outputs
The original source bytes and the chosen table are part of the result, including custom trailing zeros and unused valid table rows. report.json stores all contributions and source spans; the bounded page preview and clipboard summary do not replace that complete artifact.
Before handing off a large batch, inspect the reported formula/contribution counts, download the complete JSON/CSV and retain originals. Some coupled dimensions reach the32MiB or500,000-work guard before their other maximums. Cancellation publishes no partial files, so restart from the complete source.
References
- Original formula and explicit-weight question
First-person demand: repeated elements and multi-digit subscripts, explicit weights; prose and code tables differ.
- Pinned molmass2026.8.15 element source
Correctness and data provenance only; exact mass keyword literals and full BSD-3-Clause source notice.
Tools in this category
Expand a tool to see its steps, options and supported formats, then open its workspace.
Formula composition and declared-weight massCount every repeated element in neutral formulas, then calculate each contribution and the total using a versioned weight table or your explicit decimal weights.
Choose the weight source before calculating. Exact decimal arithmetic preserves the declared numbers; it does not make them a sample-specific or isotopic physical mass.
Steps
- Enter one supported neutral formula per line or select a UTF-8 formula file. The selected file supplies the source.
- Select the versioned fixed table or Custom table; in Custom paste every used element and its positive decimal weight.
- Inspect the formula/contribution counts and weight source, then download the complete report, composition CSV, weight table and exact originals.
Available options
- Explicit weight source
- molmass2026.8.15 declared table · Custom decimal table
Custom replaces the complete table; there is no automatic fixed-table fallback. Clear the custom-weight field before returning to the fixed table.
Capabilities and limits
- Formula source: strict UTF-8, optional retained BOM, up to1MiB,10,000 nonblank physical lines and4,096 UTF-8 bytes per formula. Only outer ASCII spaces/tabs are trimmed. CRLF/LF/CR and byte/character source spans remain in the complete report.
- Exactly109 elements H–Mt; case-sensitive ASCII symbols, positive integer counts without leading zero, nonempty nested ()/[] up todepth16. Each count token≤32 digits; intermediate element/atom counts≤512 digits. Dot . or · is a hydrate separator with an optional positive factor after it, never decimal stoichiometry.
- Charges, isotope labels/D/T, initial coefficients, states/macros/expressions, fractional counts and Ds–Og are Unsupported. Unknown symbols, empty groups, zero/negative weights, duplicate or missing used weights are rejected atomically.
- Fixed table: molmass2026.8.15 exact source decimal literals,109 rows, source SHA and full BSD-3-Clause notice. Custom mode replaces the whole table without fallback: header symbol,weight and at most109 unique rows, unsigned positive plain decimals up to6 integer/32 fractional digits, strict unquoted two-field lines, total≤16KiB. Leave the custom field empty in fixed mode.
- At most100,000 element contributions and500,000 work units; all original files, JSON and CSV combined≤32MiB. Input, formula dimensions, count growth, work and output apply together; some combinations reach a guard before their other dimensions reach a maximum.
- The table shows the first200 contributions and first2,000 UTF-16 units per long cell. Copy is a report preview above20,000 characters; all downloads remain complete. Calculated sums are exact strings; importing CSV numbers into a spreadsheet may round them. Declared average/database values do not represent physical exact mass, isotope spectra or sample uncertainty.