Formulas
volume (mL) = amount (mg) ÷ concentration
units = volume (mL) × scale (U-100: 100 · U-50: 50 · U-40: 40)
Reverse (diluent for a target reading): water = vial × target units ÷ (amount × scale). Blends: each component's amount in a draw = draw volume × (component mg ÷ total water). Micrograms are converted with 1 mg = 1,000 mcg before any other step.
The same TypeScript module computes the live calculators in your browser and every table on every page at build time, so the tool and the charts can't disagree.
Rounding and display
- All arithmetic runs at full double precision; rounding happens only for display.
- Display rounding is half away from zero, done in decimal (not binary), so 1.005 shows as 1.01.
- Units are shown to 1–2 decimals and mL to 3. Small masses get more decimals as they shrink (0.0025 mg stays visible instead of rounding to 0).
- Trailing zeros are trimmed; thousands use comma separators.
Syringe model
Barrels are modeled by capacity, scale (units per mL) and the spacing of minor tick marks on a typical barrel. Real barrels vary by manufacturer (some 0.3 mL barrels have half-unit marks), so the tick spacing is used only to warn when a result falls between marks. It never changes the computed volume.
| Barrel | Capacity | Scale | Minor mark |
|---|---|---|---|
| U-100 · 0.3 mL (30 units) | 0.3 mL | 100/mL | 1 unit |
| U-100 · 0.5 mL (50 units) | 0.5 mL | 100/mL | 1 unit |
| U-100 · 1 mL (100 units) | 1 mL | 100/mL | 2 units |
| U-40 · 1 mL (40 units) | 1 mL | 40/mL | 1 unit |
| U-50 · 1 mL (50 units) | 1 mL | 50/mL | 1 unit |
Warnings and errors
- Over capacity: the reading exceeds the barrel; the syringe drawing turns amber.
- Between marks: the reading isn't on a printed mark; the nearest mark and what it holds are shown.
- Below one mark: the volume is too small to read reliably on that barrel.
- Non-U-100 barrel: a reminder that U-40/U-50 units aren't U-100 units.
- Hard errors: missing, zero, negative or non-numeric inputs; amount larger than the vial.
Data sources
- Vial sizes on the 25 compound pages are the sizes that appear repeatedly in public research-supplier catalogs, counted across 190 catalog pages reviewed in October 2026. Sizes seen only once were dropped. Sellers are not named and not linked.
- Molecular weights and formulas come from PubChem and are linked on each page; where PubChem has no unambiguous record we leave them out.
- Regulatory status lines quote or summarize FDA, ClinicalTrials.gov, PubMed-indexed trials or the developer, and cite them on the page.
- Diluent and storage facts come from the DailyMed label for Bacteriostatic Water for Injection, CDC injection-safety guidance and Bachem's published handling guidelines.
Chart rows on compound pages are evenly spaced arithmetic increments. They're reference points for the conversion, not suggested amounts.
Testing
The math module has an automated unit-test suite (Vitest) that runs before each release. It covers:
| Rounding | Half-away-from-zero rounding with no binary-float artifacts (1.005 → 1.01). |
|---|---|
| Conversions | mcg ⇄ mg, mL ⇄ units on every barrel scale, concentration and per-unit content. |
| Worked examples | 10 mg + 2 mL, 2 mg → 0.4 mL, 40 units; 5 mg + 2 mL, 250 mcg → 10 units. |
| Float-hostile inputs | Values like 0.1 + 0.2 never snap to the wrong tick mark. |
| Warnings | Over-capacity, between-tick, below-one-tick and non-U-100 barrels are flagged. |
| Errors | Empty, zero, negative and non-numeric inputs, and amounts larger than the vial. |
| Round trips | units → mg → units returns the original value on every barrel; reverse water results feed back into the forward calculator exactly. |
| Blends | A draw splits into each component by its share of the vial. |
| Share links | Encode → decode round-trips; malformed links fall back to defaults; comma decimals (2,5) are accepted. |
Editorial review process
Pages are written and reviewed by the Peptide Vial Math Editorial Team. The team is credited as a group; no individual credentials are claimed. A page is published or updated only after it passes all of these checks:
- Math check. Every number on the page (tool output, tables, worked examples, FAQ answers) is generated at build time by the same module the unit tests cover. Hand-written figures are not allowed in tables.
- Source check. Each factual statement about a compound, a diluent, a device or a regulation is checked against the primary source it cites, on the date shown. Claims we can't verify are removed, not softened.
- Scope check. The page is read for anything that could pass as dosing advice: suggested amounts, schedules, "protocols" or trial doses presented as targets. Any found are removed.
- Independence check. No seller names, links, rankings or ratings.
- Technical check. An automated build step validates structured data, internal links and page metadata, and accessibility and performance are tested with Lighthouse.
Last full review: . Pages are re-reviewed whenever a cited source changes or a correction is reported.
What we don't do
- We don't recommend amounts, frequencies, schedules or "protocols", and we don't publish trial dose levels as targets.
- We don't rank, score or link sellers.
- We don't model purity, overfill, solubility limits or degradation. The calculator assumes the vial contains exactly its labeled mg and that it is fully dissolved.
Content last checked 2026-10-19. Found an error? See corrections.