Backcharge Cost Breakdown Calculator
Calculate and document construction backcharge costs for labour, materials, plant, specialists, testing, adjustments, credits, and payment support.
Construction Engineering Calculators & Tools
Practical calculators, estimators, selectors, checkers and decision-support tools for construction engineers, QA/QC teams, consultants and contractors.
Browse qTools
Each qTool is a focused browser-based utility designed to support a specific construction or civil-engineering task. Open a tool directly or share its permanent Quollnet link with your team.
Concrete Admixture Strategy Selector
Choose the main fresh-concrete performance change you need and identify an admixture function worth discussing with the concrete producer. This selector does not choose products, calculate dosage or design the mix.
Concrete Slump Result Action Tool
Compare a concrete slump-test result with your project requirement and review retest, adjustment and next-action records without using generic acceptance limits.
Ld Gap Sensitivity Calculator
Compare project-level liquidated damages exposure against subcontract-level LD recovery and identify the uncovered LD gap for construction contracts.
Plaster Area per Cement Bag Calculator
Calculate the approximate square meters of wall or ceiling plaster produced from one cement bag using cement:sand ratios, plaster thickness, and practical waste allowances.
QMix Auditor
Front-end concrete delivery ticket audit tool for estimating true water-cementitious ratio, hidden aggregate moisture water, 7-day strength, 28-day strength, temperature risk, admixture effect, and QA/QC warnings.
QMix Designer
Preliminary concrete mix design calculator for estimating cement, water, sand, coarse aggregate, water-cement ratio, slump, batch quantities, moisture correction, and ACI-style / Eurocode EN 206 durability checks.
QMix Logbook
A front-end concrete pour QA/QC logbook for recording batch tickets, pour times, slump, temperature, added water, sample IDs, 7-day and 28-day results, and acceptance status. Save projects as JSON/qmix and export Excel, PDF, CSV.
Rebar Development Length Calculator
Calculate the basic straight reinforcing-bar development (anchorage) length from bar diameter, design steel stress, and design bond stress. Includes an optional lap-splice multiplier and clear distinction between development length and overlap.