Conversion Guard

Conversion Guard is a free online metric conversion platform that provides instant calculators, reference tables, and formulas for converting between metric and imperial units. Operated by Wight Hat Ltd, a UK-registered company, it serves a broad audience including students checking homework, travelers navigating foreign measurement systems, engineers verifying specifications, and home cooks converting recipes. The site covers ten core measurement categories and supports 56 languages, making it one of the most accessible unit conversion resources on the web.

Key Features

• Ten conversion categories. Temperature, length, area, volume, weight, speed, time, angle, pressure, and energy and power are all covered, with each category offering multiple unit pairings and bidirectional conversion.
• Reference tables with formulas. Each conversion type includes a detailed table showing common values alongside the underlying formula, helping users understand the math rather than just seeing a result.
• Fifty-six language interface. The entire site, including category labels, calculator instructions, and table headings, is available in 56 languages from Arabic to Vietnamese, removing language barriers for international users.
• Mobile apps for iPhone and Android. Dedicated native apps replicate the full conversion engine for offline-capable use, listed on both the Apple App Store and Google Play under Wight Hat's developer account.
• Search and quick-link navigation. A built-in search box lets users type any unit pair directly, while the homepage surfaces popular conversions such as km to miles and Celsius to Fahrenheit for one-click access.
• Bidirectional conversion. Every calculator works in both directions by default, so switching from miles to kilometers and back requires no extra steps or mode toggles.
• Decimal precision control. Results display with consistent decimal rounding, and the mobile app offers up to five decimal places for users who need higher accuracy.

Conversion Categories and Calculators

The platform organizes its tools into ten measurement families. Temperature covers Celsius, Fahrenheit, and Kelvin. Length handles millimeters, centimeters, meters, kilometers, inches, feet, yards, and miles. Area converts between square meters, square feet, acres, and hectares. Volume includes milliliters, liters, fluid ounces, pints, quarts, and gallons for both US and UK measures. Weight spans milligrams, grams, kilograms, ounces, pounds, and stones. Speed covers meters per second, kilometers per hour, and miles per hour. Time converts seconds, minutes, hours, and days. Angle handles degrees, radians, and gradians. Pressure converts pascals, bar, atmospheres, and psi. Energy and power covers joules, calories, watts, and horsepower. Each category page lists all supported unit pairings with precomputed reference rows so users can scan common values without typing.

Pricing and Access

Conversion Guard is entirely free to use on the web and through its mobile apps. There are no paid plans, subscription tiers, premium features, or usage limits. The platform is supported by Google AdSense advertising, which displays contextual ads alongside conversion results. Registration is not required for any feature, and the site does not gate calculators behind a login wall. The privacy policy confirms that the site collects only standard analytics and ad-serving data, and users may browse anonymously. Wight Hat Ltd does not offer an affiliate, partner, or referral program.

Platform Availability

The web version works in any modern browser with no plugins or extensions required. The iPhone app is distributed through the Apple App Store, and the Android app is available on Google Play. Both mobile apps carry the publisher name Wight Hat and maintain feature parity with the web version, offering the same ten conversion categories and bidirectional calculation. The apps support offline use for core conversion functions, though reference tables and formula pages may require a connection to load updated content.

Pros and Cons

Pros:

• Completely free with no registration, paywalls, or usage limits.
• Broad unit coverage across ten measurement categories with bidirectional conversion.
• Fifty-six language interface makes the tool accessible to a global audience.
• Mobile apps for both major platforms with offline capability.
• Reference tables include the underlying formulas, adding educational value beyond a simple calculator.
• Simple, fast interface with direct search and quick links for popular conversions.

Cons:

• Ad-supported model means display ads appear alongside calculations, which can be distracting on smaller screens.
• No advanced features such as unit history, favorites, or custom unit definitions found in some competing converter apps.
• The website carries a disclaimer that it does not guarantee the accuracy of its conversions for any particular purpose.
• No currency conversion support, unlike some general-purpose conversion tools that combine unit and currency converters.
• Offline table access on mobile is limited; formula reference pages require an internet connection.

Who Should Use Conversion Guard

Conversion Guard is well suited for anyone who needs quick, reliable unit conversions in daily life. Students and educators benefit from the formula tables that show how conversions are derived. Travelers dealing with unfamiliar temperature scales or distance units can use the mobile app offline. Engineers, mechanics, and lab technicians who work across metric and imperial standards will find the pressure, energy, and angle categories practical. Home cooks converting between grams and ounces or milliliters and cups get direct answers without sifting through recipe sites. It is less appropriate for users who need currency conversion, advanced engineering unit systems, or an ad-free experience, as those capabilities lie outside its scope.