Formulas

A formula field computes a value from the visitor’s other answers — a per-unit total, a discount, a subtotal, or the grand total itself. Formulas are validated live as you type.

Referencing fields

Reference another field by its name in curly braces, e.g. {area} or {rate}. A reference returns that field’s current value:

• Number, slider and quantity fields return their entered number.
• A choice field (dropdown, radio, checkboxes) returns the price of the selected option(s), or 0 if nothing is selected.
• A toggle returns its price when on, 0 when off.
• Another formula returns its computed result, so you can build a formula on top of a formula.

Operators

The usual arithmetic, left to right with standard precedence:

{area} * {rate} + {callout}
( {width} * {height} ) / 1000

Supported: + − * (or ×) / (or ÷), with parentheses for grouping.

Functions

Function	Does
if(test, a, b)	Returns a when the test is true, otherwise b
min(a, b, …)	The smallest of its arguments
max(a, b, …)	The largest of its arguments
round(value, decimals)	Rounds to decimals places (decimals optional)
ceil(value)	Rounds up to a whole number
floor(value)	Rounds down to a whole number
abs(value)	The absolute (positive) value

Examples

# £45 per m², minimum charge £120
max( {area} * 45, 120 )

# 10% express surcharge when the express toggle is on
{subtotal} + if( {express}, {subtotal} * 0.10, 0 )

# round the final total to whole pounds
round( {subtotal} - {discount}, 0 )

Decimal-safe math

Calculations use exact fixed-point decimal arithmetic, not floating point — so 0.1 + 0.2 is exactly 0.3 and totals never drift by a cent. The same engine runs in the browser preview and on the server, verified against a shared test suite on every release, and the server independently recomputes every submitted quote. The number a visitor sees is the number you receive.

Tips

• Keep one formula field as your total and reference smaller formulas into it — easier to read and to debug.
• A formula can reference the same fields your conditional logic uses, so a hidden field (which counts as empty) drops cleanly out of the math.
• Circular references are caught for you — a formula can’t depend on itself.