Some prices depend on more than one choice. A gloss finish costs more on a bigger sign. A rush fee applies to some orders and not others. Premium material adds a percentage, not a flat amount.
Those are conditional pricing rules: one option changes the price of another. Shopify variants can't hold them, since each variant has one fixed price.
In Appify Custom Product Options, you build them in five places: a choice's own formula, if/then logic, price adjustments, conditional fees and rate tables. Other rules hide choices, cap sizes and fill in values. And you can describe your rules and formulas in plain English instead of building them by hand.
What counts as a conditional pricing rule?
Any line on your rate card that starts with "if" or "only when." A few common ones:
- A choice priced by size. Lamination is charged per square foot, so its price grows with the sign.
- A surcharge on one material. Premium stock costs 25% more.
- An upcharge past a size. Anything over 100 square feet gets a large-format charge.
- A fee that only sometimes applies. Rush processing, or setup on a custom shape.
- A rate that depends on another choice. The price per square foot changes with the material.
Five ways to make one option change another's price
Each kind of rule has its own home in the editor. Pick the one that matches how you'd say the rule out loud.
1. Price a choice from other options
Every choice has its own Formula and Rate. The formula can read any other option, so a finish can be priced from the size the customer typed. New to formulas? Start with what formula pricing actually means.
Work out the area once as a pricing variable called AREA. Then the gloss choice's formula is AREA times your lamination rate. When the customer changes the size, the finish price follows.
2. Put if/then inside a formula
The formula editor has IF, AND, OR and NOT. HAS checks which choice is picked. So "premium material charges 25% more on the area" becomes one line:
IF(HAS("MATERIAL", "PREMIUM"), VAR("AREA") * 1.25, VAR("AREA"))
Two more functions come in handy here. COUNT prices by how many add-ons were ticked. CHARCOUNT prices engraving by the letter.
3. Add price adjustments
Price adjustments keep conditional charges out of your main formula. Each one pairs conditions with an amount.
- Conditions are built in a visual editor, with no syntax to learn. Check a choice, a toggle, or a pricing variable like AREA over 100. Combine several with ALL or ANY.
- The amount can be a flat number, a percentage, or a formula that reads options, variables and tables.
A premium surcharge and a large-format upcharge can each be one adjustment. The live preview updates as soon as a condition matches.
4. Make a fee conditional
Fixed fees sit on top of the product price. Give one a formula like IF(HAS("RUSH", "YES"), 25, 0) and it only charges when rush is picked.
A fee that works out to zero is hidden from the customer. Fees are never discounted, so a setup fee stays whole when a quantity break kicks in.
5. Look up the rate by the customer's choice
Put your rates in a pricing table, and the formula reads the row for the material they picked: TABLE("materials", OPT_TOKEN("MATERIAL")).
A grid can key on two things at once, like size and material. Then the rate changes with both.
Quantity breaks can be conditional too. In 2D mode, a quantity discount depends on the quantity and a second value like width or area. Small signs and large signs each get their own breaks, applied at checkout with no discount code.
Which tool fits which rule?
Write your rule the way you'd say it, then find its home:
| Your rule | Where it goes |
|---|---|
| "Lamination is charged per square foot." | The choice's own formula, reading AREA |
| "Premium material costs 25% more." | IF inside the formula, or a price adjustment |
| "Over 100 square feet, add a large-format charge." | Price adjustment: AREA greater than 100 |
| "Rush adds a fee." | Fixed fee with an IF formula |
| "The rate depends on size and material." | Pricing table lookup |
| "Big runs of small signs get a deeper discount." | 2D quantity discount |
| "No order goes out under our minimum." | Minimum price on the total |
| "Engraving is only offered on wood." | Show if rule on the engraving option |
Rules that change what can be chosen
Some rules change the price by changing the options. Visibility rules show, hide or require an option when a condition matches. A hidden option is left out of the price and the cart.
- Show if: the engraving text box only appears when Material is Wood.
- Hide values: drop the choices that don't fit, like a finish that isn't made for one material.
- Limit: cap Width at 48 inches when Material is Acrylic.
- Value rules: fill in a value or lock it. "Force Finish to Matte for custom shapes." A value rule can fill in once and let the customer change it, or stay locked while it applies.
Rule conditions can read any option, a pricing variable, or the product's own Shopify Color or Size. A number can even be compared with a formula, like Quantity greater than twice the Width.
Floors, caps and discounts on the total
The total price formula brings every option together. Set a minimum and a maximum price there, plus a calculator-wide discount that can itself be a formula.
There's more on floors in setting a minimum price for custom products.
You describe the rule, AI writes it
You don't have to build the rules or write the formulas by hand. Tell Chat with AI "hide Rush order unless Size is 2in or 3in" or "when Size is Custom, set Quantity to 1, they can still change it." It writes the rule, and you can edit the result on the rule's tab.
In any formula field, Describe with AI turns "a rate per square foot, with a minimum order price" into a working formula that uses your option names. Explain formula reads any formula back to you in plain English.
What if a conditional price comes out wrong?
Conditional prices tend to go wrong in one combination, not all of them. The Troubleshoot tab runs the formula for the choices in the preview and shows what every part is worth.
It names the options a rule is hiding, like "Hidden while Finish is Gloss," and the values a rule filled in. It flags an IF whose condition is never true for those choices. Type the price you expected, and it points to the fix.
Click Price looks wrong? under the preview price to open it for the exact choices on screen. Or tell Chat with AI which choices come out wrong and what you expected.
Where to start
List your rate card's "if" lines, one per line. Match each one to the table above, and ask Chat with AI for the rules and pricing in your own words. Then test the odd combinations in the preview before you publish.
For the full set of building blocks, read how to price complex custom products on Shopify. For volume breaks, see quantity discounts for custom products.
FAQ
What is conditional pricing on Shopify?
A price that changes with what the customer picks, like a finish that costs more on a bigger size. Shopify variants give each combination one fixed price, so it takes an app with a formula engine.
Can one product option change the price of another?
Yes. In Appify Custom Product Options, any choice's formula can read other options, and price adjustments add charges when their conditions match.
How do I add a surcharge for one material?
Add a price adjustment with the condition Material equals Premium, and a flat or percentage amount. Or put an IF in the formula.
Can a fee apply to some orders only?
Yes. Give a fixed fee an IF formula. When it works out to zero, the customer doesn't see it.
Can a rule check a calculated value like area?
Yes. Pricing variables such as AREA can be used as conditions in visibility rules, value rules and price adjustments.
Do I need to write formulas?
No. Chat with AI writes rules from plain English, and Describe with AI writes formulas. Explain formula turns any formula back into plain English.
Every "only if" on your rate card, priced.
Whatever you sell, however you price it · The last options app you'll shop for