Options Price Calculator or Ex Custom Price Calculator for a price per metre?

A mural studio sells by the square foot. A gravel yard needs the checkout to understand tons. Both shops are past three variant options, and neither wants a quote form. On 10 November 2026 I opened the live listings for Options Price Calculator and Ex Custom Price Calculator. For Options Price Calculator I also opened Plans & usage limits, Using the Formula Builder, Variables and Field Values, and the server-side validation article. Shopify Help, Adding variants, was open the same morning. Extendons’ own help center was not part of this pass. I used their public listing, including the data-access block and the three reviews on screen.

Help tells you the ceiling: three options, 2,048 variants, and a note that a third-party app or line item properties are how you go past that. The formula article tells you how a sum is written. This note is the decision those two pages do not make: which published card covers unit pricing, and where Options Price Calculator’s own docs still describe a different plan ladder than the listing. Re-read both cards if a price, the free cap, the badge, or that docs gap moves.

The free cards do not say the same thing

Options Price Calculator’s listing tabs are Free, Starter, Premium, and Ultimate. The Free card has a single bullet: “Ultimate Plan for Free – 20 uses limit”. Premium is the $19.99 card. Ultimate is $39.99. No yearly price and no trial line showed on this fetch. No revenue cap showed on any card.

The plans article, still marked about two months old and signed by Floris de Vries, describes three plans. Free there is one calculator, 20 calculated orders for the life of the Free plan, basic fields, the theme app extension, and one AI generation shared with the formula assistant. It still quotes Premium near $14.99 and never mentions a $39.99 tier or the phrase “Ultimate Plan for Free”.

Keep those sources apart. The listing is what Shopify shows a merchant. The article is the usage counter the docs still explain. Do not promise Ultimate features on Free until those pages match. The number you can defend from both texts today is 20, and the docs reading of that number is calculated orders, not twenty passes through every Ultimate feature.

Ex Custom Price Calculator’s Free card is wider on the listing itself: all store plans, 9+ calculators, a custom calculator, a price-per-unit table, custom formulas, min and max purchase limits, and discounts on quantity ranges. There is no “uses” sentence. For a shop that only wants to learn whether wallpaper-by-the-metre can check out, that Free card is the stronger public offer this morning. That is a real win for Ex.

What each paid card actually names

Both apps carry Built for Shopify. Both language rows say English. Online Origins is listed in ’s-Hertogenbosch. Extendons is listed in Islamabad. That is a reachability fact, not a score.

Options Price Calculator launched on 15 August 2025. Rating 5.0 from 30 reviews, every one of them five stars. The three cards on screen were 30 October 2026 Orange Shapes, 29 October Brooklyn Butcher Blocks, and 23 October Kingdom Decals. Review number 30, if the total includes one the grid does not show, had no text on this screen. Orange Shapes and Kingdom Decals mention support. Kingdom Decals writes “reply within reasonable time”.

Ex launched on 16 September 2019. Rating 4.6 from 43 reviews: 34 fives, 3 fours, 0 threes, 2 twos, 4 ones. Cards on screen: 4 February 2026 MandalaRoseWorks (three decimal places, fixed in under a day), 7 November 2025 Trusted Building Supplies (built-in calculators and support), 24 October 2025 West Valley Rock, edited (checkout in tons, lbs, and gallons; a display issue the company helped with). The one-star write-ups were not on those three cards. Open the full list before you treat 4.6 as “no complaints”.

Ex’s hero is specific about length, width, area, volume, and weight, in the units you choose, plus bulk tiers. Options Price Calculator’s hero is specific about formulas, AI, live preview, and server-side validation, without extra variants.

A formula you can read, versus a library of calculators

The formula builder uses `+ − × ÷` and parentheses. The example on that page is `(product_price + width * height) * material_multiplier`. Numeric metafields are `product_metafield__{namespace}__{key}` and `variant_metafield__{namespace}__{key}`, and only integer or decimal metafields appear in the picker. Conditional if / then / else and `lookup2d` are Premium in the docs. The listing puts lookup tables, file uploads, live preview, the font picker, and the price breakdown on $19.99. Show/hide and draft orders sit on $39.99. The conditional article names `Math.min`, `Math.max`, `Math.ceil`, `Math.floor`, and `Math.round`.

Ex puts Look Up Table on the $29.99 card, next to round-up and a library of 100+ formulas. The unlimited-AI line sits on the $19.99 card. Options Price Calculator’s Starter card already says AI at $9.99. The docs narrow that: Free includes one AI use, Starter does not get conditional formulas from the assistant, Premium does. A hero that says “EXO AI” is not the same sentence as “unlimited custom formulas with AI” on a named tier.

That split is the practical one. Pick Ex when you want named measurement units, a stack of ready calculators, and quantity-range discounts on the free card, and you are comfortable that lookup is published at $29.99. Pick Options Price Calculator when someone in the warehouse must be able to read the formula, metafields have to enter the sum, lookup should be on the $19.99 card, and AI on the listing starts at $9.99. The younger review set (30 fives, launched August 2025) is the trade for that.

The safety switch is a feature only after you turn it on

Server-side price validation, in an article last updated six months ago, defaults to off. Off, the cart trusts `__ooCustomPrice`. On, a signature (`__ooLiteSig`) and a payload hash have to match or the line does not expand into the order. The switch is global, under Settings, Price settings. Turn it on after an end-to-end test.

This morning’s data-access block for Options Price Calculator lists cart transforms and cart and checkout validations, plus theme, Files, locales, and Markets. Script tags were not in that block. Ex’s block lists device data, products and inventory, 60 days of orders, and Online Store script tags plus theme. It does not list a Shopify Functions or validations row. That is the documented gap Options Price Calculator wins, with the caveat that a new shop is unprotected until someone saves the toggle. The listing line about server-side validation describes a capability, not the state of your store.

Units are the gap Ex wins. The listing names length, width, area, volume, and weight. A review names tons, pounds, and gallons. Options Price Calculator gives you numeric width and height inside a formula, and the listing category includes Dimensions. A unit picker that turns gallons into a checkout unit is not in the articles I opened.

Show and hide is easy to mis-score. Options Price Calculator puts conditional show/hide on the $39.99 card. Ex lists “Show and hide” as a category chip, and none of the plan cards repeat that phrase. Leave that cell unscored until a plan sentence appears.

When variants are the whole answer

Help, Adding variants, read on 10 November 2026: up to three options and up to 2,048 variants on a product. A fourth option, or a continuous centimetre, does not fit. The same page caps media at 250 items and warns that some themes and apps still stumble above 100 variants. The ceiling is not 100. 2,048 is also not a promise that every theme renders the full grid.

Stocked SKUs, such as three real roll widths you actually keep on a shelf, stay variants. A calculator on top of that is extra machinery. Line item properties, Help’s other route, store a measurement on the order line. They do not set the price.

Primary sources

• Options Price Calculator on the App Store

• Ex Custom Price Calculator on the App Store

• Plans and usage limits

• Using the Formula Builder

• Variables and Field Values

• Server-side price validation

• Shopify Help: Adding variants

On this site

The bill as order volume grows is the cost-at-scale note. The Apippa comparison is about a revenue cap. The SE comparison is about which card unlocks formulas and metadata. The three-option and 2,048-variant filter is the checklist. The theme app extension is the Built for Shopify note. Shopify apps as a service, separate from this listing: apps and integrations.

What holds on 10 November 2026

Ex wins the published Free card, named measurement units, the template library, yearly prices with a 10-day trial, and a review history that starts in 2019. Options Price Calculator wins a formula a colleague can read, metafields in that formula, AI named on the $9.99 card, lookup named at $19.99 rather than $29.99, and a written validation switch. Both badges are Built for Shopify. Neither app wins every made-to-measure shop.

Install from this listing when the formula and the validation switch are the knockout: Options Price Calculator. Drop the conclusion if the plans article catches up to four tiers, if Ex moves lookup or unlimited AI down a card, or if either rating moves hard.