iSmart Measure
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How to use the Unit Library
Search any unit to see its measurement system and the exact, cited factor behind every conversion — grounded in NIST and BIPM.
The Unit Library is the reference layer under the whole app: every unit, its system, its exact factor, and the source that backs it — so accuracy is transparent, not a black box.
Open the Unit Library and search
Choose Library from the sidebar and search for any unit by name or symbol — length, mass, pressure, energy, data and more across all 13 families.
See its system and exact factor
Each unit shows which system it belongs to (US Customary, UK Imperial or Metric/SI) and its exact conversion factor to the SI base unit.
Check the cited source
Every factor lists the authority behind it — NIST SP 811 or the BIPM SI Brochure — so you can trust and cite the numbers, not just take them on faith.
Jump straight to converting
Found the unit you need? Head to the converter to use it live — the Library and converter share the same SI-grounded factors.
Settling a debate. An engineer wants to confirm a foot is exactly 0.3048 m before citing it in a report. She searches ‘foot’ in the Library, sees it flagged as US/Imperial with the exact factor and the NIST/BIPM source, and cites it with confidence.
Use the Library whenever you need to cite a conversion — it names the authority (NIST SP 811 / BIPM) so your figures are defensible.
Frequently asked questions
What is the Unit Library?
A searchable reference of every unit iSmart Measure supports, showing each unit's system and its exact conversion factor with the cited source.
Where do the conversion factors come from?
From authoritative references — NIST SP 811 and the BIPM SI Brochure — with exact factors where the definition is exact (for example, 1 inch = 2.54 cm).
Is the Unit Library free?
Yes. The Unit Library is part of the free core of iSmart Measure.