Answer in brief
Build subtotal = strategyCost + designCost + developmentCost + contentCost. Contingency = build subtotal × contingencyPercent ÷ 100. First-year total = build subtotal + contingency + 12 × (hostingMonthly + careMonthly).
Set scope before entering any number
A website budget is useful only if everyone means the same project. Record the number and types of pages, languages, integrations, content to be supplied, migration needs and approval steps. Strategy covers discovery and planning; design covers visual and interaction work; development covers implementation and testing; content covers writing, editing and preparation. Those descriptions are budget categories, not a promise that every agency splits work identically. Ask each supplier to state deliverables and exclusions so their four figures can be compared.
The calculator has exactly seven inputs: strategyCost, designCost, developmentCost, contentCost, hostingMonthly, careMonthly and contingencyPercent. It has no separate compliance, license, advertising or tax box. You may place a quoted item in a relevant existing category, but record that choice. An empty line should mean an intentional zero, not work everyone assumes another person will fund.
Read the build and first-year equations
Add the four one-time amounts to obtain buildSubtotal. Multiply that subtotal by contingencyPercent ÷ 100 to obtain contingency; the calculator rounds the amount to cents. launchTotal is buildSubtotal plus contingency. Separately, monthlyTotal is hostingMonthly plus careMonthly, and annualRecurring is twelve times monthlyTotal. firstYearTotal adds launchTotal and annualRecurring. The reserve therefore applies only to the build subtotal, not to the monthly operation or an external annual license.
A contingency is money held for defined uncertainty, not permission to leave the scope vague. Choose its percentage as a planning assumption and decide who can authorize spending it. If none is used, the eventual paid amount may be lower than the reserved budget. If the project expands beyond its agreed scope, a reserve of any size cannot substitute for a change decision.
A hypothetical example matching every field
Imagine a fictional project with strategyCost $1,200, designCost $2,500, developmentCost $4,800 and contentCost $900. These are invented amounts for arithmetic, not market prices. buildSubtotal is $1,200 + $2,500 + $4,800 + $900 = $9,400. Set contingencyPercent to a hypothetical 12%; contingency is $9,400 × 0.12 = $1,128. The planned launchTotal is therefore $10,528.
Assume hostingMonthly $45 and careMonthly $180, also fictional. monthlyTotal is $225 and annualRecurring is 12 × $225 = $2,700. firstYearTotal is $10,528 + $2,700 = $13,228. If hosting rose to $65 with everything else fixed, the year-one number would rise by 12 × $20 = $240, reaching $13,468. The percentage reserve does not grow because the build subtotal has not changed.
Accessibility and hosting need deliberate estimates
W3C's Web Accessibility Initiative advises assigning responsibilities, resources and budget to accessibility work across planning, implementation and ongoing monitoring. The article's calculator offers no accessibility field: put a scoped audit, design review, implementation or content remediation in the corresponding build line, or mark it outside the number. Avoid declaring a site compliant merely because a line was paid; acceptance criteria and evaluation still matter. The applicable legal duties depend on the project and jurisdiction and are not calculated here.
Hosting is similarly specific to architecture and traffic. AWS's official Pricing Calculator can generate monthly and twelve-month estimates for selected services; it does not set a universal website hosting price. Use a supplier quote or a configuration estimate for hostingMonthly. Put maintenance, backups, routine updates or support in careMonthly only when your chosen agreement actually includes them. Avoid charging the same service in both fields.
Identify costs beyond the seven inputs
Annual software licenses have no separate field. If a known license is essential and you want it in the displayed first-year total, you can include one twelfth in careMonthly, while noting that cash may be due all at once. If you leave it out, show the excluded amount beside the result. The same principle applies to a separately quoted compliance audit: allocate it to an existing build line when appropriate, or disclose that the calculator excludes it. Do not silently add a new line to the widget's formula.
Taxes, domain purchase, premium imagery, translation, paid acquisition, complex data migration and future feature requests may also fall outside. Some can be placed in one of the four build or two monthly categories if genuinely scoped. Keep an external assumptions register with the estimate date, owner and payment schedule. The calculator does not forecast traffic growth or inflation.
Compare proposals and update the budget
Run each proposal through the same field definitions and the same contingency rule. One supplier may bundle care with hosting while another bills it separately; normalize those quotes before declaring one cheaper. Compare not only firstYearTotal but also who owns content, who fixes defects, how accessibility is checked and what happens after launch. A low launch quote can coexist with a high operating commitment.
After contracting, replace provisional figures with agreed prices. At launch, distinguish the reserved contingency from money actually spent. During the first year, reconcile hosting and care with invoices and record change requests separately. The calculator gives a decision-ready planning boundary; it is not an invoice, a legal assessment or a prediction of every future change.
Practical checklist
- Define pages, features, content ownership and acceptance criteria before estimating.
- Quote strategy, design, development and content separately in one currency.
- Choose a contingency percentage against the four-line build subtotal.
- Estimate monthly hosting and care from the intended operating setup.
- State where accessibility, security, licenses, taxes and change requests sit.
Questions and answers
Does the percentage reserve apply to hosting?
No. The implemented contingencyPercent multiplies only the sum of strategy, design, development and content. Hosting and care are annualized separately.
Where do compliance and accessibility costs go?
There is no dedicated field. If scoped and quoted, allocate work to the relevant strategy, design, development or content field, then document the allocation. Otherwise treat it as excluded.
Does the tool include annual software licenses?
No dedicated annual-license field exists. You can fold a known annual amount into careMonthly as one twelfth for planning, while noting its actual payment schedule, or leave it outside the displayed total.