FRP engineering unit converter
Convert strengths, moduli, loads, section properties, weights and thermal values between metric and US units, and find the metric catalog size closest to an inch profile on a US drawing.
- Quantities
- 19
- Factors
- Exact / NIST SP 811
- Inch sizes
- Fractions accepted
Convert a value
| 240 | MPa (N/mm²) |
|---|---|
| 34,809 | psi |
| 34.809 | ksi |
| 2,447.3 | kgf/cm² |
| 240,000 | kPa |
Inch profile size to a metric catalog size
Enter the size from a US drawing, in decimals or fractions such as 1/4 or 1-1/2, and see the closest F1 catalog size of the same shape.
101.6 × 101.6 × 6.35 mm
SHS 100×100×6 · 3.5 kg/m
Depth -1.6%, width -1.6%, wall -5.5% against the inch size. Check the section properties before substituting.
A metric section of nearly the same size is not automatically equivalent: check it with the FRP profile calculator or the column calculator.
Common FRP values in both systems
| Value | Given as | Converted |
|---|---|---|
| E23 lengthwise tensile strength | 240 MPa | 34.8 ksi |
| E23 lengthwise modulus | 23 GPa | 3.34 Msi |
| E17 lengthwise modulus | 17 GPa | 2.47 Msi |
| OSHA guardrail test load | 200 lbf | 0.89 kN |
| IBC guard line load | 50 lb/ft | 0.73 kN/m |
| ASCE 7 catwalk live load | 40 psf | 1.92 kPa |
| Pultruded FRP density | 1.9 g/cm³ | 119 lb/ft³ |
| FRP lengthwise thermal expansion | 8 × 10⁻⁶/K | 4.44 × 10⁻⁶/°F |
| Window U-value | 0.8 W/(m²·K) | 0.141 Btu/(h·ft²·°F) |
Material values for F1 profiles are on the technical data page, and guardrail and walkway loads by market are in the handrail load check.
Frequently asked questions
Which conversion factors does the converter use?
The exact definitions, 1 in = 25.4 mm and 1 lb = 0.45359237 kg, with standard gravity 9.80665 m/s² for pound-force and kilogram-force, and the International Table Btu for the thermal units, as listed in NIST Special Publication 811. Results show five significant figures; round them to the precision the drawing needs.
Is 1 Msi the same as 6.9 GPa?
Yes. 1 Msi is one million pounds per square inch, 6.895 GPa. The EN 13706 minimum lengthwise moduli of the E23 and E17 grades, 23 and 17 GPa, are 3.34 and 2.47 Msi, which makes them easy to compare with a US data sheet.
Can a metric profile replace an inch size from a US drawing?
Often, but check the section. Several F1 catalog sizes correspond to inch sizes, such as I 305×305×12.7 (12 × 12 × 1/2 in) and L 102×102×9.5 (4 × 4 × 3/8 in), so they match exactly. Where the closest metric size differs by a few per cent, its area, stiffness and strength differ too; run it through the profile or column calculator before substituting, and ask if the exact inch size is needed.
Why convert U-values and R-values separately?
A U-value is the heat flow through an element, and an R-value its resistance, the inverse for a single layer. US and Canadian window ratings quote U-factors in Btu/(h·ft²·°F), while Europe uses W/(m²·K); 1 Btu/(h·ft²·°F) is 5.678 W/(m²·K). Rating methods also differ (NFRC 100 against EN ISO 10077), so a converted number is not a like-for-like rating.
Working from a US or European drawing?
Send the drawing with the sizes as given; engineering confirms the matching catalog sizes or quotes the exact ones. We reply within one business day.