Units of Measurement Abbreviations

540 abbreviations in 11 subcategories

Abbreviations and symbols for metric (SI) and US customary units, cooking measurements, time, dates, time zones, data sizes and mathematics. Unit symbols are case-sensitive: mW (milliwatt) and MW (megawatt) differ by a factor of a billion, and in recipes T (tablespoon) is three times t (teaspoon).

• Engineering Unit
• Math
• Statistics
• Metric and SI Unit
• Time Zone
• Time
• Cooking
• US Customary and Imperial Unit
• Data Unit
• Day of the Week
• Month

Engineering Unit Abbreviations

Abbreviations for units of power, energy, pressure, temperature, electricity, frequency, speed, flow, sound, light, force, torque and radiation, as they appear on spec sheets, utility bills, tire placards, HVAC equipment and car reviews. Many mix SI and US customary units (psi, BTU, hp, cfm), and capitalization carries meaning: kW is kilowatts of power while kWh is kilowatt-hours of energy, and mW and MW differ by a factor of a billion.

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Math Abbreviations

Abbreviations and function names used in mathematics, from school arithmetic and geometry (GCF, LCM, PEMDAS, SOHCAHTOA, CPCTC) to calculus, linear algebra and proof writing (lim, det, iff, QED, WLOG), plus number shorthand such as K, M, MM and bn, whose meaning depends on the field. In typeset mathematics, function names such as sin, log and max are set in upright roman type to distinguish them from variables.

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Statistics Abbreviations

Abbreviations used in statistics, probability, data analysis and research reporting: descriptive measures (SD, IQR, CV), inference (CI, df, H0, p), regression and model diagnostics (OLS, R², RMSE, AIC), named methods (ANOVA, PCA, ARIMA, MCMC) and probability terms (PDF, CDF, iid). Style guides such as the APA Publication Manual specify how statistical symbols are written, usually in italics for letters such as M, SD, n, p and t.

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Metric and SI Unit Abbreviations

Symbols of the International System of Units (SI) and the wider metric system: base units, derived units such as the newton and tesla, the 24 decimal prefixes from quecto- to quetta-, and everyday metric units of length, mass, volume and area. SI symbols are case-sensitive, take no period and are never pluralized, so 5 kg is correct and 5 Kgs is not. The system is maintained by the International Bureau of Weights and Measures (BIPM), and since 20 May 2019 every base unit has been defined by a fixed constant of nature.

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Time Zone Abbreviations

Abbreviations for time standards (UTC, GMT, TAI) and regional time zones, with their offsets from Coordinated Universal Time and their daylight saving rules. Many abbreviations are ambiguous, since CST, IST, BST, AST and PST each name more than one zone, so international schedules are clearest when they add a UTC offset (UTC-5) or an IANA zone name such as America/New_York. In the US and Canada, daylight saving time runs from the second Sunday in March to the first Sunday in November; in the EU and UK, from the last Sunday in March to the last Sunday in October.

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Time Abbreviations

Abbreviations for units of time (s, min, h, d, wk, mo, yr), clock notation (AM, PM), business and fiscal periods (FY, Q1 to Q4, H1, YTD, YoY), calendar eras (AD, BC, CE, BCE, BP) and date formats such as MM/DD/YYYY and ISO 8601. Conventions vary: the SI symbols for second and hour are s and h, while everyday English prefers sec and hr, and the order of day and month in numeric dates differs between the United States and most other countries.

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Cooking Abbreviations

Recipe and kitchen abbreviations for volume, weight, package and ingredient sizes, food labels and restaurant menus, as printed in cookbooks, recipe cards, packaging and prep sheets. Case matters in recipes: a capital T usually means tablespoon and a lowercase t means teaspoon, three times smaller. US, British, Australian and metric cups and spoons differ slightly in volume, so conversions on these pages assume US customary measures unless stated otherwise.

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US Customary and Imperial Unit Abbreviations

Abbreviations for the inch-pound units used in the United States and, in imperial form, in the United Kingdom and other former British territories: length, area, volume, liquid and dry capacity, and weight. Since the 1959 international yard and pound agreement these units have been defined exactly in metric terms (1 inch = 25.4 mm, 1 pound = 0.45359237 kg). US and imperial volumes differ, so an imperial gallon, pint or fluid ounce is not the same size as its American namesake.

All 43 US customary and imperial unit abbreviations →

Data Unit Abbreviations

Abbreviations for units of digital information, data transfer rates, storage endurance, computing performance and display and print resolution. Two prefix systems coexist: decimal SI prefixes (kilo = 1,000), used by drive makers, carriers and network speeds, and binary IEC prefixes (kibi = 1,024), introduced in 1998 and used by many operating systems, which is why a "1 TB" drive shows up as about 931 GB in Windows. Case matters: a lowercase b means bit and a capital B means byte, eight times larger.

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Day of the Week Abbreviations

Abbreviations for the days of the week in three-letter, longer and one- or two-letter forms, as seen on calendars, timetables, store hours and class schedules. English day names come from Old English and honor the sun, the moon and Germanic gods who were matched with Roman ones. One-letter schedule codes vary by institution: many US universities use R for Thursday so it cannot be confused with T for Tuesday.

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Month Abbreviations

Standard abbreviations for the months of the Gregorian calendar, as used in calendars, tables, document dates and data formats. The three-letter forms (Jan, Feb, Mar and so on) appear on calendars and in software, while AP style abbreviates only Jan., Feb., Aug., Sept., Oct., Nov. and Dec., and only with a specific date; March, April, May, June and July are always spelled out. May has no abbreviation because its name is already three letters long.

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Edited by the AbbreviationList.com team. Spotted an error or a missing meaning? Contact us.