Toolchest · Datasheet

Accumath Toolchest — Unit Conversion Factors (NIST SP 811)

Dataset: accumath-unit-conversions.csv — 451 rows

Source

• NIST Special Publication 811, 2008 Edition (2nd printing, November 2008), Guide for the Use of the International System of Units (SI), by Ambler Thompson and Barry N. Taylor. Appendix B, §B.9 "Factors for units listed by kind of quantity or field of science."
• DOI: 10.6028/NIST.SP.811e2008. Official PDF obtained from NIST (nvlpubs.nist.gov).
• SP 811 is a U.S. Government publication: public domain, no license or permission required for use.

Convention

• Each row converts from a non-SI (or non-preferred) unit to the SI unit named in to_unit_SI:

value in SI unit = numerical value in from-unit × factor

• Only the to-SI direction is listed. To convert SI → from-unit, divide by the same factor.
• Factors are reproduced in SP 811's own scientific notation, including its digit-grouping style (digits grouped in threes by spaces, e.g. 9.806 65 E+00, 1.055 056 E+03). No factor was recomputed, rounded, or taken from any other source.
• Per SP 811 (§B.2), factors are based on the international foot unless the unit name says otherwise; U.S. survey foot variants are separate rows wherever SP 811 lists them.

Exactness (factor_is_exact)

• SP 811 states: "Factors in boldface are exact." The factor_is_exact column transcribes that boldface from the PDF's embedded font data (147 exact, 297 not exact).
• The column is blank for the 7 type = formula rows; the boldface convention does not apply to formulas.

Contents

The complete §B.9 table: 444 numeric factors + 6 temperature formulas + 1 reciprocal instruction (mile per gallon → liter per 100 km, which SP 811 prints as "divide 235.215 by number of miles per gallon"), grouped into 41 quantity classes. Largest classes: Pressure or stress (47), Volume (44), Electricity and magnetism (38), Length (35), Energy (29), Mass (24), Mass divided by volume (18), Area (16).

The Heat class keeps SP 811's own bold sub-groupings as subclasses (e.g. "Heat — Thermal Conductivity", "Heat — Specific Heat Capacity and Specific Entropy").

Formulas (type = formula)

Temperature conversions are not single factors; the factor cell carries SP 811's formula verbatim in its T/K, t/ºC notation, e.g. t / ºC = (t / ºF − 32) / 1.8, T / K = t / ºC + 273.15. (The 1.8 divisor is SP 811's printed form of the 9/5 ratio.) Temperature interval conversions are ordinary factors and appear under "Temperature interval".

Symbols

• Superscripts are written as Unicode characters (m², ft³, m⁻¹, s⁻¹).
• Subscripts, which SP 811 prints as true subscripts, are written with an underscore: Btu_IT, Btu_th, cal_IT, cal_th, cal_15, mmH_2O, g_n.
• Degree is written with SP 811's glyph º (e.g. ºC, ºF).
• Parenthetical qualifiers that SP 811 prints as part of a unit name stay in the name — e.g. "acre (based on U.S. survey foot)", "day (sidereal)", "horsepower (boiler)", "kip (1 kip = 1000 lbf)" — and the symbol column is left empty for those units, as printed.

What is not included (gaps)

• §B.8 lists the identical factors alphabetically by unit name. It was not transcribed separately; doing so would duplicate all 451 rows.
• The cross-reference-only headings in §B.9 (Capacity, Density, Flow, Force divided by area, Mass density, Mass divided by capacity, Speed, Stress, Torque, Work) contain no rows in SP 811 itself; their entries live under the headings they point to.
• SP 811's numbered footnotes to §B.9 (which qualify certain units — the U.S. survey foot, the therm, the several gallons, etc.) are not reproduced. Footnote reference numbers were removed from unit names. The factors are unaffected, but a reader who needs a footnote's qualification should consult SP 811 directly.
• §B.10 (rounding guidance) is prose, not factors, and is out of scope.

Source quirks found (values kept as printed)

1. Kayser (Length): §B.9 prints the factor as 1 E+02 — the ".0" is absent in the printed 2008 edition (§B.8 prints 1.0 E+02). Numerically identical and exact either way; transcribed as printed in §B.9.
2. One to-unit name is printed "watt per square meter Kelvin" with a capital K (British thermal unit_th per second square foot degree Fahrenheit row); all other rows print "kelvin". Kept as printed.
3. The PDF text layer drops the closing parenthesis in two places — "henry (H" (EMU of inductance row) and "(gal / min" (first gallon (U.S.) per minute row). The symbols are recorded as H and gal / min, matching the parallel entries.

Verification

• Extracted at character level from the official NIST PDF, so every digit and every boldface flag comes from the document itself, not from a secondary transcription.
• The 444 numeric factors reconcile exactly with the count of exponent tokens in §B.9, and every factor's digits were verified verbatim against an independent text extraction (poppler) of the same PDF — zero mismatches.
• Boldface (exactness) was cross-checked against the PDF's embedded font data (TimesNewRomanPS-BoldMT), and spot renderings of printed rows agree.