Convert between the stress, modulus, and density units that appear across materials datasheets — pascals and their multiples, psi and ksi, and the metric and imperial density units. Pick a category, enter a value, and choose the units to convert from and to.
Materials datasheets are a patchwork of unit systems: a modulus might be quoted in GPa, a yield strength in ksi, and a density in lb/in³ or g/cm³ depending on where the data came from. Mixing these up is an easy way to be off by orders of magnitude. This converter handles the two families you meet most often in materials work — stress/modulus and density — by converting every input through a single SI base unit, so the result is always consistent.
Each unit is stored as a factor that expresses one of that unit in the category's SI base unit (pascals for stress, kg/m³ for density). To convert, the calculator multiplies your value by the factor of the source unit to get the SI base value, then divides by the factor of the target unit. So converting X from "from" to "to" is simply X · factor[from] / factor[to]. The intermediate SI base value is shown in its own card so you can see the anchor of every conversion.
Stress, pressure, and elastic modulus all share units of force per area. In SI that is the pascal (Pa = 1 N/m²), but a pascal is tiny, so engineers use kPa (10³), MPa (10⁶), and GPa (10⁹). The imperial counterparts are psi (pounds per square inch, 6894.76 Pa) and ksi (1000 psi, 6.89476 × 10⁶ Pa). The handy rule of thumb is 1 ksi ≈ 6.895 MPa, so a 50 ksi yield strength is about 345 MPa.
Density is mass per volume. The SI base here is kg/m³. The most common materials unit, g/cm³, is exactly 1000 kg/m³ (water is 1.000 g/cm³ = 1000 kg/m³). Imperial densities are pounds per cubic inch (lb/in³ = 27679.9 kg/m³) and pounds per cubic foot (lb/ft³ = 16.0185 kg/m³). Because a cubic inch and a cubic foot differ by a factor of 1728, lb/in³ and lb/ft³ are wildly different in magnitude — a frequent source of errors.
Routing every conversion through one SI base unit avoids accumulating rounding errors and makes the logic auditable: each unit needs only one factor, and any pair of units in a category converts correctly without a special-case table. It also makes the converter easy to extend — adding a new unit means adding one number. When you change category, the from/to selectors reset to valid units for that category so you never end up converting a stress unit into a density unit.
Divide by about 6.895: since 1 ksi ≈ 6.89476 MPa, a stress in MPa divided by 6.89476 gives ksi. For example, 345 MPa ÷ 6.895 ≈ 50 ksi. The converter does this exactly by routing both units through pascals.
GPa (10⁹ Pa) is conventionally used for elastic moduli, which are large — steel's Young's modulus is about 200 GPa. MPa (10⁶ Pa) is used for strengths and applied stresses, which are smaller — typical yield strengths run from tens to a couple thousand MPa. Quoting a modulus in MPa or a stress in GPa is technically valid but unconventional and error-prone.
Both express density in pounds, but over different volume units. A cubic foot is 1728 times larger than a cubic inch, so the same material has a numerically far larger value in lb/ft³ than in lb/in³ (steel is about 0.284 lb/in³ but roughly 490 lb/ft³). Always check which volume unit a datasheet uses.
Yes, exactly. There are 1000 grams in a kilogram and 1,000,000 cubic centimetres in a cubic metre, so the two factors combine to make 1 g/cm³ equal to 1000 kg/m³. Water's density is 1.000 g/cm³ or 1000 kg/m³ — a useful checkpoint.
No — this tool focuses on the stress/modulus and density quantities that dominate materials datasheets. For pressure, flow, and process quantities, use a dedicated process converter; the principle (route through one SI base unit) is the same.