Last updated: January 2026
Most estimating software asks you to trust a number. ConstrCalc is built on the opposite premise: that you should be able to see exactly how every figure was produced, and that anything the tool cannot derive from your own inputs should not appear at all.
Every quantity, rate, duration, headcount and percentage used in a calculation comes from you. Where the platform pre-fills a figure — a standard material consumption, for instance — that figure is editable, visibly marked as a starting point, and immediately replaced the moment you type over it.
A value you supply is never silently adjusted, weighted, averaged against undisclosed data, or overridden by a heuristic. If you enter fifteen labourers for twenty days at a given day-rate, the calculation is fifteen multiplied by twenty multiplied by that rate. Nothing else is applied.
The Formula Library documents each calculation the platform performs: subtotal composition, overhead application, profit application, contingency, grand total, and every unit and area conversion. The formulas are written out rather than described, so you can reproduce any result by hand.
This matters commercially. An estimate you cannot audit is an estimate you cannot defend when a client questions it, and a figure whose derivation you cannot explain is a figure you should hesitate to sign.
Overhead and profit are applied in sequence, not added as a single combined percentage. Overhead is calculated on the subtotal; profit is then calculated on the subtotal plus overhead. On a $100,000 subtotal, 15% overhead followed by 10% profit produces $126,500, not the $125,000 a flat 25% would suggest.
That difference is not a rounding artefact. Applied across a year of work it is the gap between a comfortable margin and a marginal one, which is why the sequence is stated openly rather than buried in the arithmetic.
The platform applies no undisclosed regional factor, no inflation adjustment, no risk loading, and no assumed shift length. An earlier version converted a day-based labour entry into hours using an assumed eight-hour day; that assumption was removed precisely because it was invisible to the user and altered their figures without consent.
Where a genuine assumption is unavoidable — a standard consumption baseline, for example — it is disclosed on the Sources page and made editable in the interface.
ConstrCalc does not forecast costs, does not learn from other users' projects, and does not compare your figures against a proprietary database to nudge them. There is no model making a judgement you cannot inspect.
This is a deliberate limitation. A predictive tool might feel more sophisticated, but it would produce numbers you could not defend line by line, and it would require collecting the project data we specifically do not collect.
Calculator inputs, saved projects and generated reports live in your browser's local storage. Supplier rates you have negotiated, margins you apply, and the projects you are pricing are not transmitted to us and are not visible to anyone else. The Privacy Policy sets this out in detail.
Standard quantities, cost ranges and country conventions are published with their origin and their limitations stated on the Sources page. Where a figure reflects a particular construction type or market convention, that context is given rather than implied.
The platform is funded by advertising. Advertisers have no influence over calculation logic, published formulas, guide content, or which materials and methods are described favourably. Editorial independence is set out in the Editorial Policy.
When we get something wrong, the correction is published with a dated note on the affected page rather than folded in silently. If you find an error, tell us at info@constrcalc.com.
Construction estimating sits inside a chain of accountability. A contractor prices a job, a client questions a line, a quantity surveyor reviews the build-up, and occasionally a dispute puts the whole calculation in front of somebody adversarial. At every step, the question is the same: where did this number come from?
A tool that answers that question in full is more useful than one that produces a more confident-looking figure by means you cannot describe. That is the reasoning behind every constraint on this page — not a marketing position, but a judgement about what estimators actually need when the number is challenged.
The corollary of a tool that assumes nothing is that it depends entirely on the quality of what you supply. Rates should be burdened rather than bare, so that payroll taxes, insurance and statutory benefits are inside the labour figure. Quantities should be measured from drawings once drawings exist, rather than carried forward from a baseline. Wastage should be entered explicitly rather than hoped for.
Assumptions you make should be written down alongside the estimate, not held in memory. The platform will preserve your figures faithfully; it cannot preserve the reasoning that produced them unless you record it.
Any figure on the summary can be traced. Take the grand total, subtract the profit line, subtract the overhead line, and you have the subtotal. Subtract the four category totals and the arithmetic closes. Each category total is the sum of its visible line items, and each line item is a quantity multiplied by a rate you can see.
Exported PDF, Excel and Word reports carry the same breakdown, so an estimate can be checked by somebody who has never opened the platform. That is the practical test of transparency: whether the working survives being handed to a stranger.
If a published formula looks wrong to you, or a result does not reconcile with your own hand calculation, we want to hear about it. Write to info@constrcalc.com with the figures you entered and the result you expected. Challenges of that kind have improved this platform before and will again.
