Custom calculators / specialist tools
You may already have the formula, spreadsheet or way of working. Let’s turn it into a clear experience: sensible questions, visible assumptions and a result someone can understand.
From your rules to a useful answer
A few places to start
Work directly with Marshall at Nexney, based in Durban, South Africa. Start with the question your customer or team keeps asking, then decide what a tool should help them do.
Guide a customer or team member through the relevant options. Calculate an indicative result from approved rules and carry the chosen configuration into an enquiry.
Show how a change in volume, time or capacity affects a plan. Let the reader explore the relationship without having to understand a large spreadsheet.
Help someone narrow a complicated choice. Use agreed compatibility and selection rules to build a useful specification or request for review.
An example first project
A focused browser-based calculator with an agreed input form, explicit formula, result breakdown, validation and responsive layout. A small set of reference cases establishes what the tool should return before the design is polished.
The quotation defines the calculations, number of scenarios, review rounds, editable settings, exports and integrations. Saved accounts, payment, live external data and regulated sign-off are separate requirements.
Explore the working demonstration ↗The detail behind the interface
An attractive answer is only useful when the calculation behind it is understood. We establish that foundation with the person who owns the business rules.
Confirm what each input means, what ranges are allowed and when to round. Test zero, missing, very small and very large values as well as the ordinary case.
Use cases you have already checked. Agree the expected results and what should happen when a combination cannot be calculated.
Keep the important caveats beside the result. Explain which figures are user-supplied, which are fixed assumptions and whether an answer needs expert review.
Decide who can change rates or rules, how those changes are reviewed and which examples must still pass. Ongoing support can adapt the tool as your offer evolves.
Portfolio calculators and architecture scenes use illustrative data. They demonstrate interaction and design thinking; they are not professional advice or evidence of a client’s private system.
From a spreadsheet to a clearer journey
You can begin with a spreadsheet, written formula or a worked example. The first step is understanding how a correct answer is reached.
Review the current method, user, input sources and the decision the result supports.
Implement the agreed rules against reference examples before extending the scope.
Make the questions, controls, result and next step clear on phone and desktop.
Publish as a focused tool or connect it to a website, enquiry journey or existing platform.
Tell me what you calculate, what makes it awkward and who needs the answer. Include a sanitised example if you have one.
Before we begin
Often, yes. We first inspect the formulas, dependencies, data sources and expected results. Some tools are best kept in a spreadsheet; others benefit from a guided web interface or a connection to an existing platform.
It can prepare an estimate or quote draft from approved rules, inputs and rates. You decide which results are indicative, which need review and who may issue a final quotation. The interface should make those limits clear.
Yes, with the right source of domain knowledge. You or your appointed specialist supplies and approves the formulas, units, assumptions and acceptance examples. Nexney designs and implements the tool; regulated engineering, financial or other professional sign-off stays with the qualified reviewer.
Most calculations should use explicit, testable rules. AI can help interpret a brief or draft an explanation where appropriate, while the numerical calculation remains traceable to the agreed inputs and formula.
