Changelog.

Added Open data

The unit definitions, converter factors and engineering tables behind the site are now free to download as CSV and JSON under CC BY 4.0: 183 unit definitions with their official sources, 109 converter factors, common conversion values, AWG wire geometry, NPT thread dimensions, water density, boiling point by altitude, wind chill, the task paths and the verification records. Tables from copyrighted standards are not included.

Pages: Open data

Added Task paths

23 common jobs, such as wiring a motor circuit, drilling and tapping a hole, sizing a gas line or converting a recipe, now link their converters, charts, calculators and guides in order. Each page in a task shows a Next step link under its tool and a numbered list of the whole task with this page marked. Where a job continues on one of our other free tools (voltage drop, AC size, stairs, concrete in cubic yards, solar batteries, tank volume, baking, dimensional weight), the task links to it.

Pages: Ohm's law calculator · Tap drill chart · Gas pipe sizing calculator · Cooking conversion chart

Fixed Checked against official sources: 14 pages, with corrections

Fourteen pages whose sources are free to read were checked value by value against the official documents, and each now says what was checked. Corrections: the decibel chart's NIOSH exposure limits at 75–105 dB (for example 90 dB is 2 h 31 min, not 2 h) and OSHA's 85 dBA action level; several °F/°C pairs, the USDA freezer temperature and a USDA note on medium-rare beef in the temperature chart; three NPT E1 values; the boiling-point calculator now uses geopotential altitude as the 1976 Standard Atmosphere requires; and the gas pipe calculator now stays at or below the International Fuel Gas Code tables (it could pick a pipe one size too small at the edge of a table). Smaller wording and rounding fixes on the cooking, ideal gas, heat loss, feet and inches, slope, solar and log board feet pages, and a stray voltage-divider note removed from ten calculators.

Pages: Decibel chart · Temperature reference chart · NPT pipe thread chart · Gas pipe sizing calculator · Boiling point of water

Added Sources & verification box and this changelog

Every converter and value page now lists the official definition of each unit it uses (NIST SP 811, NIST Handbook 44, BIPM SI Brochure) with links. Cheat sheets, calculators and guides show their sources in the same box. Each box gives the date the page's content last changed and, where a check was done, the date the data was verified.

Changed Metric and imperial values on six more cheat sheets

ASTM steel grades now give ≈ MPa next to ksi, bearing sizes give inches, bolt torque gives both N·m and ft·lbf, HVAC duct sizing gives mm and L/s, thermocouple types give °F, and copper pipe gives mm for wall and inside diameter. Each value is converted from the one on the sheet, and each sheet states the factor and rounding.

Pages: ASTM steel grades chart · Bearing size chart · Bolt torque chart · HVAC duct size chart · Thermocouple types chart · Copper pipe size chart (Type K, L, M)

Fixed AWG wire gauge PDF: column labels

In the printable PDF, the labels of the two-row table header sat one place off from their values (for example "Area" over the millimetre diameters). The numbers were correct, and the web page was not affected. The PDF now labels every column.

Pages: AWG wire gauge chart

Changed Tools first

On converter, calculator and lookup pages, the tool now sits directly under the page title, so it is on screen without scrolling on phones. The short answer follows it.

Removed Adsterra advertising

The site now shows Google AdSense only. The privacy policy and cookie notice were updated.

Pages: Privacy policy

Fixed Independent accuracy audit of every conversion factor

All 190 units were checked against NIST SP 811, NIST Handbook 44 and the BIPM SI Brochure with exact arithmetic. Factors are now exact for US volume units, torr, knot, BTU/h, ft·lbf, horsepower, ton of refrigeration, US gallons per hour, foot-candle and grains per gallon. The converter names the definition it uses where more than one exists (thermochemical calorie, International Table BTU, conventional inch of mercury and inch of water, international acre). In page text, 58 values called "exact" were rounded values and now say so, last-digit errors in fluid ounce, UK gallon, cubic metre, millilitre, cup and AWG tables were corrected, and 200 kcal now reads 837 kJ.

Fixed Number input

Converters and search now read 1,000 · 1,5 · 1/2 · 3 1/2 · ½ · 1e3 correctly and give no answer for text they cannot read. Temperatures below absolute zero are refused.

Fixed Calculator review

Beam load span uses size-specific No. 2 design values (SPIB, WWPA); duct sizing uses the ASHRAE friction equation (the earlier fit gave 25–50 % too much airflow) and refuses ducts over 24 in; wire gauge adds the 75 °C termination column (NEC 110.14(C)) and voltage drop at 75 °C; wind chill shows the NWS frostbite zones; drill clearance holes now exceed the screw diameter; the machining calculator converts inputs when the unit changes.

Pages: Beam load span · Duct sizing · Wire gauge for amperage and run length · Wind chill calculator · Drill bit for screw size · RPM ↔ surface speed

Added Search, embeds, conversion charts and favourites

Site search (press / or Ctrl+K) with unit-aware answers such as "5 mm to in"; an embeddable version of every converter; a conversion chart of common values on each converter page; ☆ Save and recently used pages, kept on your device.

Added Printable cheat sheets in Letter and A4

All 28 cheat sheets have a Letter and an A4 PDF with a QR code back to the live page, and a chart image on the page. The full set is one 64-page binder.

Pages: Cheat sheets index

Added Copper pipe, NPT threads and log board feet

New copper pipe size chart (Type K, L, M), NPT pipe thread chart and log board-feet calculator.

Pages: Copper pipe size chart (Type K, L, M) · NPT pipe thread chart · Log board foot calculator

Changed Value pages

Height, weight and dosing value pages give data specific to each value. Teaspoon pages without a dosing use now redirect to the converter.