Where our numbers come from.
Every conversion on Unittrans traces back to a published standard or a vendor specification. This page lists those sources, what they are used for, and how often they are checked.
Datasets and their origins
Each page discloses the factor it uses
| Dataset | Source | Used for | Review cadence |
|---|---|---|---|
| General unit factors | NIST SP 811 — Guide for the Use of the International System of Units (SI) | Length, weight, volume, and speed conversions | Reviewed quarterly and whenever a standard is revised |
| SI definitions | BIPM — SI Brochure (9th edition) | Base-unit definitions and exact conversion constants | Reviewed with each SI Brochure update |
| Ingredient densities | USDA FoodData Central | Cup-to-gram factors for flour, sugar, butter, honey, and other ingredients | Reviewed quarterly; each ingredient page names its measuring convention |
| Shoe and clothing sizes | ISO 9407 (Mondopoint) and national size tables | US, EU, and UK size comparisons | Reviewed quarterly; brand variation is noted on the chart itself |
| GPU specifications | Vendor specification pages — NVIDIA, AMD, Apple | VRAM, memory bandwidth, and FP16 compute for AI calculators | Reviewed quarterly; each field is labelled as a vendor figure |
| API and cloud pricing | Official provider pricing pages | LLM API cost comparisons and GPU rental estimates | Reviewed quarterly; each page shows its verification month |
One factor, displayed once.
Unit factors are stored once in the site's data files. Page tables are generated from those factors at build time, and the interactive converter reads the same values in the browser. That is why a pre-calculated row and the live result always match — there is no separate rounded copy to drift out of date.
Where a source publishes an exact value, we keep full precision and round only for display. Where practice varies — a cup of flour is the classic example — we state the convention we use (spooned and leveled, 120 g per US cup) and note that other publishers may use a different one.