UnitConvertLab:
Universal Unit Converter & Calculator
UnitConvertLab is a free, comprehensive online tool for length, mass, temperature, volume & more. Convert, calculate, and explore 450+ units across 36 categories offline.
Calculations Run in Your Browser
Core unit calculations run on your device, without an account. The website uses analytics and advertising services; see our Privacy Policy.
Works Offline
No internet required after initial load
No Data Uploads
All calculations stay on your device
No Login Required
Start converting immediately
Convert, Calculate & Visualize Units Instantly
Multiple modes for different needs—from quick lookups to detailed reference tables.
Simple Mode
Quick conversions with auto-format and instant results
Advanced Mode
Multi-step calculations with precision control
Reference Mode
View conversion tables and formulas
36 Categories & 450+ Units
From everyday measurements to scientific calculations
More Features
Who Is This For?
Students
Science, math, engineering homework and assignments
Engineers
Technical calculations and precision work
Professionals
Quick daily conversions for work
Scientists
Research calculations and unit verification
Popular Conversions
Quick links to the most searched unit conversions worldwide
From the Blog
Read all articlesCM to Inches: Formula, Chart and Fast Mental Math
Convert centimeters to inches exactly: 1 cm = 0.3937007874 in. Formula, a printable chart, mental shortcuts and the standards behind the number.
KG to LBS: Exact Formula, Chart and Common Pitfalls
Convert kilograms to pounds accurately: 1 kg = 2.20462262 lb. Includes the exact definition, a body-weight chart, mental shortcuts and pound variants to avoid.
MM to Inches: Exact Formula, Fraction Chart and Tolerances
Millimeters to inches made exact: divide by 25.4. Decimal and fractional charts, drill and fastener sizes, and how much rounding your tolerance allows.
How UnitConvertLab works
1. Pick a category, or just type
Choose one of 36 categories — length, mass, temperature, volume, area, speed, pressure, energy, data, fuel economy, typography, blood sugar, shoe size, wire gauge and more — or press Ctrl+K and type a plain-English query such as "5 km to miles" or "180 C in F". The parser understands symbols, plurals, abbreviations and compound inputs like 5 ft 11 in.
2. The conversion runs in your browser
Your value is converted to the category's base unit, then to the target unit, in your browser. Loaded unit converters work offline. Online services such as currency-rate updates need a connection; analytics and advertising can also make network requests.
3. See the formula, not just the number
Every result is shown with the formula that produced it, the exact conversion factor, a worked example and a reference table of common values. Adjust the displayed precision, swap the direction in one tap, save the pair to favourites, or copy a shareable URL that reopens the exact same conversion.
Who UnitConvertLab is for
UnitConvertLab is built for people whose numbers have consequences: engineers and drafters moving between metric and imperial drawings, students checking homework against a shown formula, nurses and clinicians converting doses, weights and blood-sugar readings, cooks scaling recipes between grams, cups and millilitres, machinists working in thousandths, and land buyers in South Asia, East Asia and the Middle East reconciling a bigha, tsubo or dunam with hectares and acres.
What makes it different is provenance. Most converters give you a number and no way to check it. Every factor here is traced to a primary standard — the BIPM SI Brochure, NIST SP 811, ISO and IEC standards, or the national authority that defines a traditional unit — and each page states the source, the verification date and any known regional variation. Corrections are logged publicly rather than quietly edited, and the underlying data is available as open JSON for anyone who wants to audit or reuse it.
It stays free, needs no account, and saves your preferences in your browser. Analytics and advertising are disclosed in our Privacy Policy. If a unit is missing or a factor looks wrong for your region, tell us — regional accuracy benefits from the people who use those units every day.