A wall isn't measured in one unit. Customers say "ten feet, six inches," and your price is per square foot.
This is a look inside the Wallpaper calculator on our Shopify demo store. It's built with Appify Custom Product Options.
The shopper enters the wall's width and height in feet and inches, picks a design, and opens a preview. The price per square foot follows the design, and the total appears with the preview.
What it does
Under the heading "Enter Wall Size" are a Width and a Height, each split into a feet box and an inches box. Below them are five round design swatches, including Pattern, Birds, Fish and Trees. A blue Preview & Show Price button sits at the bottom.
In plain words, the price is the wall's area in square feet, times the rate for the design.
Why a wallpaper calculator is hard to build
- Customers measure in two units. Feet and inches go in separate boxes, but the price needs one number. The calculator joins them into total inches first, so 10 ft 6 in is 126 inches, and nobody has to convert.
- The rate depends on the design. Different designs can sell at different prices per square foot. The design swatch carries its own rate, and the price formula reads it.
- The shopper wants to see the wall before they pay. The product image switches to the design they pick, and the preview shows the wall at the size they typed.
- The area has to be right. Width times height in inches is square inches. Wallpaper is sold by the square foot, so the formula divides by 144.
- The order has to keep the exact wall. Customers can fix a measurement from the cart, and a reorder brings the wall back as ordered.
One price, worked out
Here's a wall 10 feet wide and 8 feet high in the Birds design, with prices in dollars.
- Width and height in inches: 10 ft is 120 inches. 8 ft is 96 inches.
- Area: 120 × 96 = 11,520 square inches, divided by 144 is 80 square feet.
- Rate: the Birds design is 7.10 per square foot, shown in the summary as Price / sq ft.
- Total: 80 × 7.10 = 568.00.
The design decisions
Two boxes per measurement, one number for the price
The Width and Height options each have a feet box and an inches box. Two pricing variables, WIDTH and HEIGHT, turn each pair into inches: feet times 12, plus inches. The price never has to know the customer typed two numbers.
The rate lives on the swatch
Each design carries its own price per square foot. Pattern is 5.50, Birds is 7.10, Fish is 6.50 and Trees is 8.00. A third pricing variable, UNITPRICE, reads the chosen swatch's rate.
Add a design and you add its rate in the same place. There is no table to extend and no formula to edit. The new swatch carries its own price.
One formula for the whole price
The total price formula is area in square feet times the rate: width times height, divided by 144, times the design's rate. Because the variables do the unit work, the formula stays short enough to read at a glance.
The summary shows what the customer needs
The price summary lists the rate as "Price / sq ft" and then the total. It does not break the total into lines. The customer sees why the number changed when they pick a different design.
The design swatch also swaps the picture
Personalization is on, with a layer that swaps the product image for the design the shopper picked. The product image switches to the design they pick.
The price button is the preview
There is no separate Calculate button. The last option, Preview & Show Price, opens the Product Designer. It shows the wall at the size typed, with the design, panel guides and a figure for scale, and the total sits at the bottom of the side panel.
What arrives with the order
The calculated price goes to checkout on one cart line. No wall size or design becomes a Shopify variant.
Cart properties carry the width, the height and the design to the order, so your print shop knows the wall.
Customers can tap Edit options in the cart to fix a measurement without starting over. Later, Appify Reorder brings the order back with every choice filled in, where Shopify's own Buy again drops them.
Make it yours
- Add a minimum order. A minimum price keeps a small wall from selling below your costs.
- Price by material. Let the shopper pick a paper or vinyl, each with its own rate. Wallpaper by material walks through one.
- Add a pattern repeat. How to set the pattern repeat covers repeats in the designer.
Get this calculator
Ask Chat with AI to build the options and rules in your own words. For example:
"Build a wallpaper calculator. Width and height, each in feet and inches. Five design swatches, each with its own price per square foot. The price is width times height in inches, divided by 144, times the design's rate. Show the rate and the total in the summary, and add a preview button that opens the Product Designer."
Wondering how the whole wallpaper business fits together? Read how to sell custom wallpaper by wall size.
FAQ
Can customers enter a wall in feet and inches?
Yes. Width and height each have a feet box and an inches box, and the calculator joins them before it prices.
Can each design have its own price per square foot?
Yes. The rate sits on the swatch, and a pricing variable passes it to the formula.
Does each wall size create a Shopify variant?
No. Options and pricing live outside Shopify's variant system, and the calculated price is charged on one cart line.
Can customers see the wall before they buy?
Yes. The preview shows the wall at the size they typed, with the design and a figure for scale.
Can customers change the size after adding to cart?
Yes. Edit options in the cart reopens the calculator with their choices filled in.
Every wall, priced to the square foot.
Whatever you sell, however you price it · The last options app you'll shop for