Useful Excel Calculator - basic LEV Maths

A Practical Calculation Aid for LEV Practitioners

LEV calculations are a routine part of design, testing, and assessment — yet they’re also one of the most common sources of simple, repeatable errors.

Converting between area, velocity, and volumetric flowrate.
Rearranging formulas on site.
Double-checking duct sizes under time pressure.

The Basic LEV Maths Excel Calculator was created as a practical support tool for LEV practitioners who want a quick, structured way to check calculations while keeping full ownership of the engineering judgement behind them.

This is not a “black box” calculator — it’s a transparent, formula-based worksheet designed to mirror the maths used in everyday LEV work.

A Simple, Structured LEV Calculation Tool

The calculator is laid out across four clearly labelled tabs, each aligned with common LEV tasks encountered during design, inspection, and COSHH Regulation 9 TExT work.

Tab 1 – Basic LEV Maths

A reference tab covering core LEV mathematical relationships, helping reinforce understanding of how area, velocity, and volumetric flowrate interact.

Tab 2 – Find the Volumetric Flowrate

Enter duct or hood area and air velocity to calculate volumetric flowrate (Q).
Useful for checking system balance, conservation of mass, and expected performance.

Tab 3 – Find the Duct Size from Volumetric Flowrate

Calculate duct diameter from a known volumetric flowrate.
Particularly useful when reviewing design intent, modifications, or legacy systems.

Tab 4 – Find the Duct Size from Hood Area and Velocity

Work backwards from hood requirements to establish appropriate duct sizing, supporting hood design checks and airflow justification.

Designed for Reliability — Not Accidental Changes

To prevent accidental deletion or overwriting of calculations:

• All formula cells are locked

• Input cells are clearly identifiable

• The structure is fixed to maintain consistency and repeatability

This ensures the calculator behaves the same way every time it’s used — supporting defensible calculations and clear documentation.

Important Professional Note

This calculator is intended as a calculation aid, not a replacement for competence.

While every effort has been made to enter formulas correctly, no guarantee can be given that the spreadsheet is free from errors. Users are expected to:

• Understand the underlying maths

• Sense-check results

• Verify calculations manually where necessary

• Apply professional judgement at all times

If any errors are identified, feedback is actively encouraged so corrections can be made.

Why This Tool Matters

In LEV work, small mathematical errors can lead to:

• Incorrect duct sizing

• Inadequate transport velocities

• Misinterpreted test results

• Poor capture at the hood

• Weak or indefensible Reg 9 conclusions

This calculator helps reduce avoidable mistakes, improves consistency, and supports clearer thinking — while keeping responsibility firmly with the practitioner.

Who This Calculator Is For

This Excel calculator is suitable for:

• LEV engineers and testers

• Trainee LEV practitioners

• Occupational hygienists

• Designers and installers

• Anyone carrying out LEV calculations as part of COSHH compliance

It works particularly well alongside LEV107: Basic LEV Maths, reinforcing the calculations explained in the guide.

Product Details

• Product: Basic LEV Maths Excel Calculator

• Format: Microsoft Excel spreadsheet

• Tabs: 4 (Basic Maths, Flowrate, Duct Size from Q, Duct Size from Area & Velocity)

• Formulas: Locked to prevent accidental editing

• Use Case: LEV design checks, TExT support, training, and verification

• Author: Louise Davies Wood