Engineering calculators you can defend in an audit
Field-tested calculators for mechanical, QA, and construction engineers. Built by a 25-year practicing engineer, validated against published code anchors.
Open the AQL calculatorFour pillars, thirteen calculators live
Thirteen calculators are live now. A new tool ships most weeks — Beam deflection and UT thickness are next. Seven reference charts and guides sit alongside them, listed below the calculators.
QA & Quality Control
Sampling, capability, and equipment effectiveness for inspection and audit work.
Welding & Inspection
Welding and non-destructive testing math, tied to AWS D1.1 and ASME IX.
Mechanical Design
Bolt torque, threads and ASME B31.3 pipe design, with the charts behind them.
Construction & Site
Everyday site engineering: concrete mix and rebar weight.
Reference charts and guides
The tables and background the calculators are built on: grades, nut factors, threads, pipe sizes and sampling.
Why another calculator site?
Because most of the ones ranking today get the engineering wrong. They skip the parts of the standard that are inconvenient to code, and the error lands on whoever signs the inspection report.
Case: ANSI/ASQ Z1.4 arrow rules
For a lot of 280 pieces at AQL 1.0, most online AQL tools return a sample size of 32. The arrow rules move that cell: the correct plan is n = 50, Ac 1 / Re 2. Every TorqueCalcs tool is checked against published anchor values like this before it goes live — the AQL calculator passed 12 out of 12.
Each page states its scope and its code reference. Where a tool covers single sampling under normal inspection only, the page says so instead of pretending otherwise.
Built by one engineer, not a content farm
I’m Sajid Pervez, a mechanical and QA engineer with 25 years across contracting, fabrication, and inspection. These are the calculations I have run on real projects, turned into tools I would trust myself.
- PMP — Project Management Professional
- ISO 9001 Lead Auditor
- ASNT NDT certified
- 25+ years in mechanical & QA engineering
Common questions
Are the calculators free?
Yes. No account, no email gate, no usage limit. The site exists to be useful and to demonstrate how these tools should be built.
Which standards do the tools follow?
Each calculator names its source on the page: ANSI/ASQ Z1.4 for AQL sampling, ASME B31.3 for pipe wall thickness, ASME Section VIII for vessels, AWS D1.1 and ASME IX for welding. The reference and edition are stated next to the tool. The standards themselves are published by ASQ, ASME, AWS and ISO.
Can I use the results for real inspection or design decisions?
The tools are validated against published anchor values, and each page states its exact scope and limits. Always confirm the code edition and any contract-specific requirements that apply to your project; the calculators support engineering judgment, they do not replace it.
Start with the sampling plan
The AQL calculator handles the arrow rules most tools skip.
Open the AQL calculator