All Unit Conversions

Printable reference packs

Several reference sheets bound into one PDF for a trade, a course or a classroom: print one file for the van, the workshop wall, the flight bag or a revision folder. Every sheet in a pack also has its own page with the tables in HTML, a worked example and its sources.

By Miguel Coelho · Edition 2.0 · 9 November 2026 · Free to print and share under CC BY 4.0

Electrician and Electronics Reference Pack

For: Electricians, apprentices, electronics students, technicians and makers

Six reference sheets for the van, the workbench or the classroom: electrical units, Ohm’s law and watts-to-amps, the AWG wire size chart, transformer and generator currents in kVA and kW, the resistor and capacitor colour codes with E-series values, a power conversion chart and battery mAh to Wh with airline limits. Each sheet is also available on its own.

What’s inside (6 sheets)

  1. Electrical Units Conversion Chart — Watts to amps at common voltages, Ohm's law, electrical units and symbols, energy in kWh and mains supply by country
  2. AWG Wire Size Chart (Gauge to mm, mm² and kcmil) — American Wire Gauge 4/0 to 40: diameter, area in mm² and kcmil, copper resistance and nearest metric size
  3. kVA and kW to Amps Chart (Single and Three Phase) — Full-load current for transformers and generators, single- and three-phase, 120 V to 600 V
  4. Resistor Color Code Chart and Calculator — Colour bands, multipliers, tolerance and tempco, E-series values, SMD and capacitor codes
  5. Power Conversion Chart — Watts, kilowatts, horsepower, BTU/h and tons of refrigeration
  6. mAh to Wh Battery Chart and Airline Limits — Milliamp-hours to watt-hours for phone cells, power banks and battery packs, with airline limits
Download A4 PDFDownload US Letter PDF

Machinist and Maker Reference Pack

For: Machinists, fabricators, toolmakers, makerspaces and engineering students

Six sheets for the workshop wall or the toolbox lid: number, letter, fractional and metric drills with tap drills for UNC, UNF and ISO threads; every 1/64 inch as a decimal and in millimetres; millimetres to inches; sheet-metal gauges for steel, stainless and aluminium; angles in degrees, minutes and seconds; and the everyday engineering multiply-by factors. Each sheet is also available on its own.

What’s inside (6 sheets)

  1. Drill Size Chart and Tap Drill Chart — Number, letter, fractional and metric drills in decimal inches and mm, with UNC, UNF and metric tap drills
  2. Fraction to Decimal Chart (Inches and mm) — Inch fractions to decimals and millimetres in 1/64 steps, plus inches to decimal feet for construction and surveying
  3. Millimeters to Inches Conversion Chart — Decimal inches with the nearest 1/64 inch
  4. Sheet Metal Gauge Chart — Gauge 3 to 30 in inches and mm for steel, galvanized steel, stainless steel and aluminium
  5. Angle Conversion Chart — Degrees, radians, gradians, arcminutes and arcseconds, plus slope and roof pitch
  6. Engineering Conversion Chart — Multiply-by factors for the units engineers convert every day, with SI prefixes
Download A4 PDFDownload US Letter PDF

Pipe and Plant Engineering Reference Pack

For: Process, piping and plant engineers, pipefitters, boiler operators and students

Six sheets for the control room, the site office or the classroom: ASME B36.10M and B36.19M pipe dimensions by schedule, saturated and superheated steam tables (IAPWS-IF97) in SI and US customary units, pressure units, liquid volume and flow rates, and temperature in °C, °F and K. Each sheet is also available on its own.

What’s inside (6 sheets)

  1. Pipe Schedule Chart (NPS, OD and Wall Thickness) — NPS ⅛ to 24 inch and DN: outside diameter, wall thickness by schedule, inside diameter and mass per length
  2. Steam Tables (Saturated and Superheated, SI Units) — Saturated steam by temperature and by pressure, and superheated steam, in SI units (IAPWS-IF97)
  3. Steam Tables in US Units (°F, psia, BTU/lb) — Saturated and superheated steam in °F, psia, BTU/lb and ft³/lb (IAPWS-IF97)
  4. Pressure Conversion Chart — psi, kPa, bar, atm, Pa, MPa, mbar and Torr
  5. Fluid Volume and Flow Conversion Chart — US and UK liquid measures, fluid ounces and flow rates
  6. Temperature Conversion Chart — Celsius, Fahrenheit and Kelvin side by side
Download A4 PDFDownload US Letter PDF

HVAC and Refrigeration Reference Pack

For: HVAC and refrigeration technicians, building services engineers, apprentices and students

Six sheets for the service van or the plant room: pressure–temperature tables for R-410A, R-32, R-454B, R-22, R-134a, R-404A, R-407C and R-290; heat transfer units including U-value, R-value and RSI; power in kW, BTU/h and tons of refrigeration; pressure units; temperature; and energy in kWh, BTU and therms. Each sheet is also available on its own.

What’s inside (6 sheets)

  1. Refrigerant PT Chart (R-410A, R-32, R-454B, R-22, R-134a) — Saturation pressure–temperature tables for R-22, R-32, R-134a, R-290, R-404A, R-407C, R-410A and R-454B
  2. Heat Transfer Units Conversion Chart — Thermal conductivity, U-value, R-value and RSI, heat transfer coefficient, heat flux and specific heat
  3. Power Conversion Chart — Watts, kilowatts, horsepower, BTU/h and tons of refrigeration
  4. Pressure Conversion Chart — psi, kPa, bar, atm, Pa, MPa, mbar and Torr
  5. Temperature Conversion Chart — Celsius, Fahrenheit and Kelvin side by side
  6. Energy Conversion Chart — Joules, kWh, calories, BTU and therms
Download A4 PDFDownload US Letter PDF

Site Engineer Reference Pack

For: Site and setting-out engineers, surveyors, construction managers and civil engineering students

Five sheets for the site office: US and metric rebar with steel area per metre, slopes as percent, ratio and angle, and concrete volumes for slabs; engineering multiply-by factors; metric, imperial and nautical lengths; fractions of an inch and inches to decimal feet; and angles, slopes and roof pitch. Each sheet is also available on its own.

What’s inside (5 sheets)

  1. Rebar Size and Weight Chart (US and Metric) — US #3 to #18 and metric 6 to 50 mm bars: diameter, area, weight per foot and per metre, plus site quick tables
  2. Engineering Conversion Chart — Multiply-by factors for the units engineers convert every day, with SI prefixes
  3. Length Conversion Chart — Metric, imperial and nautical lengths with a full factor matrix
  4. Fraction to Decimal Chart (Inches and mm) — Inch fractions to decimals and millimetres in 1/64 steps, plus inches to decimal feet for construction and surveying
  5. Angle Conversion Chart — Degrees, radians, gradians, arcminutes and arcseconds, plus slope and roof pitch
Download A4 PDFDownload US Letter PDF

Pilot Reference Pack

For: Student and private pilots, flight instructors, dispatchers and aviation students

Seven sheets for the flight bag or the ground-school classroom: the 14 CFR 91.175(h) RVR to visibility table with metric RVR, the ICAO standard atmosphere with density altitude, crosswind and headwind components, speed in knots, mph, km/h and m/s, temperature, US and imperial gallons to litres, and kilograms to pounds. For study and planning only: always use the approved flight manual and current published procedures.

What’s inside (7 sheets)

  1. RVR to Visibility Conversion Chart — Runway visual range in feet and metres, the 14 CFR 91.175 RVR-to-visibility table, and statute miles to metres
  2. Standard Atmosphere Table (ISA) — ICAO standard atmosphere (ISA) temperature, pressure, density and speed of sound by altitude, with density altitude
  3. Crosswind Component Chart — Crosswind and headwind components for wind angles from 0° to 90° and wind speeds up to 50 knots
  4. Speed Conversion Chart — km/h, mph, m/s, knots and ft/s, with the Beaufort wind scale
  5. Temperature Conversion Chart — Celsius, Fahrenheit and Kelvin side by side
  6. Gallons to Liters Conversion Chart — US and UK (imperial) gallons to litres
  7. Kilograms to Pounds Conversion Chart — Body weight, luggage and kitchen weights in pounds and ounces
Download A4 PDFDownload US Letter PDF

Classroom Unit Conversion Pack

For: Teachers, students, tutors and home-schooling families

Six sheets for the classroom wall, revision folders or homework: the one-page metric conversion chart with SI prefixes, a formula sheet with a worked example for every conversion, and full tables for temperature, length, weight and volume. Pair it with the free unit conversion worksheets and answer keys. Each sheet is also available on its own.

What’s inside (6 sheets)

  1. Metric Conversion Chart (One Page, Printable) — US customary and imperial to metric on one page: length, area, volume, weight, speed, pressure, energy and temperature
  2. Unit Conversion Formulas Cheat Sheet — The formula for every common conversion, with the reverse formula and a worked example
  3. Temperature Conversion Chart — Celsius, Fahrenheit and Kelvin side by side
  4. Length Conversion Chart — Metric, imperial and nautical lengths with a full factor matrix
  5. Weight Conversion Chart — Kilograms, pounds, stones, grams and ounces
  6. Volume Conversion Chart — Litres, US gallons, UK gallons, quarts and pints
Download A4 PDFDownload US Letter PDF

Engineering Unit Conversion Chart Pack

For: Engineers, technicians, students and workshops

Four reference sheets for the desk, workshop or classroom: everyday engineering multiply-by factors with SI prefixes, a pressure chart (psi, kPa, bar, atm, MPa, Torr), a power chart (W, kW, hp, BTU/h, tons of refrigeration) and a length chart (metric, imperial and nautical). Each sheet is also available on its own.

What’s inside (4 sheets)

  1. Engineering Conversion Chart — Multiply-by factors for the units engineers convert every day, with SI prefixes
  2. Pressure Conversion Chart — psi, kPa, bar, atm, Pa, MPa, mbar and Torr
  3. Power Conversion Chart — Watts, kilowatts, horsepower, BTU/h and tons of refrigeration
  4. Length Conversion Chart — Metric, imperial and nautical lengths with a full factor matrix
Download A4 PDFDownload US Letter PDFMore about this pack

Radiation Safety and Radiologic Technology Pack

For: Radiologic technology and health physics students, radiographers, nuclear medicine and radiation safety staff

Five reference sheets for the department, classroom or survey kit: SI and traditional radiation units with weighting factors, dose-rate conversions with yearly totals, typical doses from imaging and everyday sources, mCi ↔ MBq tables with decay factors for common radionuclides, and radiography formulas with dose limits compared. Each sheet is also available on its own.

What’s inside (5 sheets)

  1. Radiation Units Conversion Chart — Exposure, air kerma, absorbed, equivalent and effective dose, and activity in SI and traditional units
  2. Radiation Dose Rate Chart (µSv/h, mrem/h, mR/h) — µSv/h, mrem/h and mR/h with yearly totals, time to 1 mSv and reference levels
  3. Radiation Dose Chart: X-ray, CT and Everyday Doses — Typical doses from X-rays, CT, mammography, nuclear medicine and everyday sources, in mSv and mrem
  4. Nuclear Medicine Decay and Activity Chart — mCi ↔ MBq tables and decay factors for Tc-99m, F-18, Ga-68, I-123, I-131 and Lu-177
  5. Radiography Formulas and Dose Limits Chart — Inverse square law, exposure formulas, grid factors, half-value layers and dose limits compared
Download A4 PDFDownload US Letter PDFMore about this pack

Printing and using a pack

  • Duplex and staple. Print double-sided and staple at the top left. Every sheet starts on a new page, so a single sheet can be pulled out and pinned up.
  • Laminate the ones you use daily. The sheets are designed to print clearly in black and white as well as in colour.
  • Check the edition. The edition number and date are on every page footer. Corrections change the edition, so you can tell whether a printed copy is current.
  • Mix your own. All 38 sheets used in these packs, and the rest of the library, can be downloaded one at a time from the chart library.

For teachers: worksheets with answer keys

The classroom pack pairs with free unit conversion worksheets on metric units, imperial to metric, temperature, SI prefixes, area and volume, and speed. Each has 20 questions, a worked example and a full answer key with working.

Reference pack FAQs

Licence, accuracy, paper sizes and corrections.

Are the reference packs free to print and share?

Yes. Every pack is free under the Creative Commons Attribution 4.0 licence (CC BY 4.0). You can print it for your crew, class or company, put it on an intranet or a course page, and share copies, as long as you credit All Unit Conversions with a link.

Is a pack different from the individual charts?

No. A pack is a cover page with contents followed by the same sheets that have their own pages on this site, so a value in a pack is always the value on the reviewed, audited sheet. Download a single sheet from its chart page if you only need one.

How are the values checked?

Conversion values are generated from the exact unit definitions (NIST SP 811, the BIPM SI Brochure and the 1959 International Yard and Pound Agreement) and the build stops if any value disagrees. Reference data such as pipe schedules, drill sizes and the RVR table is transcribed from the published standard or regulation and checked against a second source, which is cited on each sheet.

A4 or US Letter: which should I print?

Use A4 in the UK, Europe, Australia and most of the world, and US Letter in the United States and Canada. Both editions have the same content; the layout is adjusted to fit each paper size.

Can I use the pilot pack in the cockpit?

Use it for study, planning and the classroom. Flight decisions must rely on the approved aircraft flight manual, current published procedures and official weather and NOTAMs.

Can I suggest a new pack or report an error?

Yes. Use the contact page to suggest a pack for your trade or course, or to report an error. Corrections are fixed in the next edition and the edition number on every sheet changes.