In 1983, Air Canada Flight 143 ran out of fuel at 41,000 feet because ground crew calculated the fuel load in pounds instead of kilograms. The jet glided to an emergency landing — passengers survived, but the cause was a unit conversion error. Magnet Press exists to make those errors impossible. Free, precise, and offline-capable, it covers every unit conversion you'll regularly need.
How to Use Magnet Press's Unit Converters
Every converter on Magnet Press works the same way: enter a value, select your units, and the result appears instantly — no buttons, no page reloads. Each conversion pair has its own dedicated page with the formula, a reference table, and expert context.
- Navigate to a category hub (e.g., Length, Weight, Temperature) using the navigation above.
- Select the 'from' and 'to' units from the dropdowns on any category hub page.
- Alternatively, click directly on a specific conversion pair (e.g., 'cm to in') from the category hub.
- Type any value in the input — the result updates instantly.
All 14 Unit Converter Categories
Magnet Press provides dedicated converter hubs for 15 measurement domains, covering everyday and technical needs:
- Length (11 units) — measuring distances, heights, and dimensions.
- Weight (7 units) — measuring mass and weight of objects and substances.
- Volume (10 units) — measuring liquid and dry goods quantities.
- Area (6 units) — measuring two-dimensional surface extent.
- Temperature (3 units) — measuring thermal energy and heat levels.
- Speed (4 units) — measuring rate of motion over distance.
- Time (7 units) — measuring duration and elapsed periods.
- Pressure (5 units) — measuring force applied per unit area.
- Energy (6 units) — measuring capacity to do work or transfer heat.
- Power (4 units) — measuring rate of energy transfer.
- Force (4 units) — measuring pushes and pulls on objects.
- Torque (3 units) — measuring rotational force around an axis.
- Angle (3 units) — measuring rotational extent between two lines.
- Data Storage (5 units) — measuring digital information size.
- Time (7 units) — measuring common time durations.
Why Unit Conversion Accuracy Matters
Unit errors have consequences ranging from mildly inconvenient to catastrophic:
- NASA Mars Climate Orbiter (1999): Lost when one team used metric and another used imperial units. Cost: $327 million.
- Air Canada Flight 143 (1983): Ran out of fuel mid-flight due to a kg/lb error. Emergency glide landing required.
- Columbus's voyage (1492): Miscalculated the size of Earth partly due to confusion between Roman miles and Arabic miles — he thought he'd reached Asia.
- Medical dosing: Milligram-vs-microgram errors and lb-vs-kg weight errors in pediatric dosing can cause serious harm.
- Construction: Bridge supports, building foundations, and structural calculations must use consistent units throughout.
The Metric System vs. Imperial Units
The SI metric system (Système International d'Unités), formalized in 1960, is the world standard for science, medicine, and trade in 195 countries. Its elegance lies in its structure: all units relate by powers of 10. Converting km to m? Multiply by 1,000. Converting mg to g? Divide by 1,000.
The imperial/US customary system uses historically evolved ratios: 12 inches to a foot, 3 feet to a yard, 1,760 yards to a mile. These reflect medieval trade conventions, not mathematics. The US, Liberia, and Myanmar are the only countries that haven't officially adopted the metric system for everyday use.
In practice, most US professionals deal with both: scientists and doctors use metric; construction workers, car mechanics, and pilots use a mix. This dual reality is exactly why unit converters remain essential daily tools.
Date Calculator and World Clocks
Beyond unit conversion, Magnet Press provides two additional tools:
- Date Calculator: Find any future or past date from today, or calculate the difference between two dates. Handles month-length variations, leap years, and year rollovers automatically.
- World Clocks: Live, second-accurate clocks for New York, London, Tokyo, Dubai, Sydney, Singapore, and other major cities — with timezone information and UTC offsets.
Who Uses Unit Converters?
Magnet Press is built for everyone who regularly crosses between unit systems:
- Students and teachers: Physics, chemistry, and math assignments require unit fluency across metric and imperial.
- Engineers and scientists: Technical specifications span multiple unit systems depending on country and industry.
- Chefs and home cooks: Recipes from different countries use different volume, weight, and temperature units.
- Travelers: Speed limits, distances, and weather forecasts use different units abroad.
- Healthcare professionals: Medication dosing, body measurements, and lab values use both systems.
- E-commerce and shipping: International parcel dimensions and weights must be converted accurately.
Frequently Asked Questions About Magnet Press
How many unit conversions does Magnet Press support?
Magnet Press provides converters for 14 measurement categories with over 500 individual unit-pair pages. Categories include length, weight, volume, area, temperature, speed, time, pressure, energy, power, force, torque, angle, and data storage. Every unit in each category converts to every other.
Are Magnet Press's unit converters accurate?
Yes — all conversions use the exact SI-defined factors or official mathematical formulas (for temperature conversions). Calculations run to full 64-bit floating-point precision. Magnet Press shows sufficient significant figures for both everyday and technical use.
Does Magnet Press work offline?
Each page is a standalone HTML file. Once a page has loaded, the converter calculations run entirely in your browser — no internet connection needed. Bookmark any converter page for instant offline access.
Why did NASA lose a spacecraft over unit confusion?
In 1999, the Mars Climate Orbiter was lost because one engineering team used metric units (Newton-seconds) while another used imperial units (pound-force seconds). The spacecraft missed Mars orbit and burned up. This $327 million disaster underscores why reliable unit conversion tools matter in professional contexts.
What's the difference between the US metric system and the SI system?
The US uses the US customary system (miles, pounds, gallons, Fahrenheit) for everyday life while using SI metric for science and medicine. The SI system (Système International d'Unités), adopted by 195 countries, uses base units (meter, kilogram, second) with decimal prefixes (kilo, centi, milli).
What is the date calculator used for?
Magnet Press's date calculator finds dates X days/weeks/months from today or in the past, calculates the difference between two dates, and provides specialized pages for common intervals (30 days from today, 90 days from today, etc.). It's commonly used for contract deadlines, subscription expirations, and project planning.
Conclusion
Magnet Press brings together all the unit conversion tools you'll regularly encounter — 85 units across 15 categories, 500+ conversion pairs, a date calculator, and world clocks. All tools are free, ad-free, and work offline after first load. Navigate to any category above, or search for a specific conversion to get started.