Free uncertainty calculator — formal reports from £75

Prove your DP flowmeter meets its uncertainty requirement

ISO 5167 / ISO 5168 uncertainty analysis for orifice plates, venturi tubes and flow nozzles. Flow-weighted compliance verdicts and audit-ready reports for EU ETS, fiscal metering, OIML verification, and internal technical review.

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ISO 5167-1:2022 ISO 5168:2005 GUM (ISO/IEC 98-3) EU ETS MRR OIML R117 NFOGM
The Problem
Uncertainty analysis shouldn't take longer than the measurement
Every EU ETS verification, every fiscal metering audit, every NFOGM review demands documented proof that your DP flowmeter meets its uncertainty threshold. Today, that means one of these:
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THE SPREADSHEET
A home-built Excel file that's been passed between engineers for years. Nobody's sure if the sensitivity coefficients are right. The verifier has to take your word for it.
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THE CONSULTANT
£2,000–5,000 per analysis. Three-week turnaround. A 40-page report where 35 pages are boilerplate and the flow-weighted uncertainty is never checked. You needed it last Friday.
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THE ENTERPRISE SOFTWARE
Desktop-only. Annual licence fee. A sales call before you can even see pricing. Requires training to use. Overkill for a single meter check.
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METERPROOF
Enter your meter data. Get the uncertainty analysis with flow-weighted verdict. Generate a stamped 8-page audit report. Twenty minutes, £75, done. Your verifier gets a traceable document with calculation workings, instrument register, and verification URL.
How It Works
From meter data to audit report in three steps
The free calculator gives you the full analysis on screen. When you need formal documentation for a verifier, generate the stamped report.
01
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ENTER YOUR METER DATA
Primary element type, bore dimensions, DP transmitter specs, fluid properties, compensation setup, lab sample data, instrument serial numbers, and annual flow profile. The tool guides you through each input with ISO 5167 references and typical values.
02
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REVIEW THE ANALYSIS
See the compliance verdict, expanded uncertainty, flow-weighted uncertainty from your annual flow profile, dominant contributors, turndown curve, and flow bias estimate — free, instantly. Iterate your inputs until you're satisfied the analysis is correct.
03
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GENERATE AUDIT REPORT
One click produces a stamped 8-page PDF: compliance verdict with flow-weighted uncertainty, full budget, step-by-step calculation workings, complete input record, instrument register, and flow profile back-test. Hand it directly to your verifier.
Pricing
One price. One report. No subscription required.
The calculator is free to use — unlimited calculations, no login. Pay only when you need the formal audit report.
£75
per audit report
A stamped, 8-page verifier-ready uncertainty analysis document. Less than an hour of consultant time.
✓ Full uncertainty budget — every contributor with sensitivity coefficients and variance %
✓ Flow-weighted uncertainty from annual flow profile — the true operational uncertainty, not just design-point
✓ Flow bias analysis from lab density data with over/under-read estimate
✓ Step-by-step calculation workings with ISO clause citations for every budget row
✓ Complete input record with documented exclusion justifications
✓ Instrument & document register — serial numbers, calibration certs, PM references
✓ Stamped PDF with unique serial number and online verification URL
✓ ISO 5168:2005 / ISO 5167-1:2022 methodology reference
⬡ Start Free Calculation
The calculator is free. Run as many analyses as you need. The report is how you prove it.
EU ETS MRR Tier 1–4
Fiscal / Custody Transfer
OIML R117
UK SMPMS / NSTA
Process Metering
Custom Threshold
Selected reading
Report preview, methodology, and technical articles
Use these pages to inspect the report structure, review the methodology, and explore technical questions around uncertainty, laboratory data, and compliance responsibilities.
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EXAMPLE REPORT
See the structure of the formal PDF output, including the compliance verdict, audit identifiers, laboratory density flow-bias section, and uncertainty budget.
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METHODOLOGY
Review the standards basis, Type A and Type B treatment, sensitivity coefficients, and what the reported result does and does not mean.
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IS IT WORTH IMPROVING?
Compare the current case with a realistic improved case and judge whether tighter uncertainty is likely to matter before investing effort.
Browse technical articles
Your meter. Your data. Your proof.

Enter your real operating conditions. See the real uncertainty. Generate the real report.

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