Free Unit Converter for Engineers & Everyday Use

An engineering-grade unit converter, built for accuracy

EngiConvert was built for people who need conversions to be exactly right — structural, mechanical and civil engineers checking stress values in ksi and MPa, students converting torque from lbf·ft to N·m, and anyone who just needs to know how many kilometers is 10 miles. Every conversion factor used on this page is an exact, published standard value (for example, 1 inch is defined as precisely 25.4 mm), and results are shown to 8 significant figures so you can trust the number whether you're filling in a spreadsheet or a stress report.

Why unit systems still collide in engineering practice

Most of the world standardized on SI (metric) units decades ago, but engineering practice didn't follow uniformly. US structural and mechanical codes still specify yield strength in ksi, torque in lbf·ft, and pressure in psi. Aerospace drawings mix inches and millimetres on the same sheet depending on which supplier produced which part. A UK civil engineer reading an American datasheet, or a US manufacturer sourcing a metric fastener, runs into the same wall: two measurement systems that were never designed to talk to each other. That's the practical reason a converter like this earns its place in a browser tab rather than being a one-off lookup — the need for cross-system conversion doesn't go away as projects progress, it recurs at nearly every handoff between a metric and an imperial source.

Engineering categories

Alongside the everyday conversions, EngiConvert covers the categories engineers reach for most often:

• Pressure / Stress — Pa, kPa, MPa, GPa, bar, psi, ksi, atm, mmHg, kgf/cm². Used for material yield/tensile strength, hydraulic system ratings, and fluid pressure.
• Force — Newtons, kilonewtons, pound-force, kilogram-force, dyne. The basis for load calculations and free-body diagrams.
• Torque / Moment — N·m, lbf·ft, lbf·in, kgf·m. Fastener torque specs, motor output, bending moments.
• Energy & Power — Joules, kWh, BTU, horsepower (mechanical and metric). Motor ratings, HVAC loads, energy audits.
• Density — kg/m³, g/cm³, lb/ft³, slug/ft³. Material selection, buoyancy and load calculations.
• Area Moment of Inertia — mm⁴, cm⁴, m⁴, in⁴, for structural beam and column section properties.
• Typography / Print — points, picas, twips, pixels, en. For web/UI layout, print production and CAD text sizing where font units need to match physical dimensions.

Everyday categories

The same engine also covers the conversions everyone searches for: Length (km, miles, cm, inches, feet), Mass (kg, lbs, stone, ounces), Temperature (°C, °F, K), Area, Volume, Speed, Time and Angle.

A worked example: specifying a bolt's torque in two unit systems

Say a fastener spec calls for 45 N·m of tightening torque, but your torque wrench only reads in lbf·ft. Select Torque / Moment, set "From" to N·m and "To" to lbf·ft, enter 45 — the tool returns roughly 33.2 lbf·ft. The same conversion works in reverse for a US spec sheet quoting 25 lbf·ft that needs to go into a metric assembly drawing (≈ 33.9 N·m). It's a small calculation, but getting it wrong on a structural or safety-critical fastener has real consequences, which is exactly why the underlying factor (1 lbf·ft = 1.3558179483314 N·m) is kept to full precision rather than a rounded rule of thumb.

A worked example: why a 12pt font renders as 16px

Select Typography / Print, set "From" to Point, Computer and "To" to Pixel X, enter 12 — the result is exactly 16 px. That's not a coincidence: browsers have long treated 1 CSS pixel as 1/96 inch and 1 computer point as 1/72 inch, so a 12pt font (12/72 = 1/6 inch) works out to exactly 16px (16/96 = 1/6 inch too). It's why "the default browser font size is 16px" and "body text is usually set at 12pt" are really the same statement in two different unit systems — useful to know when a design handoff specifies type in points but a stylesheet needs pixels, or vice versa.