Title: HDWebmobile Formula Pricing Author: HDWebMobile Published: October 13, 2026 Last modified: October 14, 2026 --- Search plugins ![](https://ps.w.org/hdwebmobile-formula-pricing/assets/banner-772x250.png?rev=3745071) ![](https://ps.w.org/hdwebmobile-formula-pricing/assets/icon-256x256.png?rev=3745071) # HDWebmobile Formula Pricing By [HDWebMobile](https://profiles.wordpress.org/htrxuan/) [Download](https://downloads.wordpress.org/plugin/hdwebmobile-formula-pricing.1.0.0.zip) * [Details](https://wordpress.org/plugins/hdwebmobile-formula-pricing/#description) * [Reviews](https://wordpress.org/plugins/hdwebmobile-formula-pricing/#reviews) * [Installation](https://wordpress.org/plugins/hdwebmobile-formula-pricing/#installation) * [Development](https://wordpress.org/plugins/hdwebmobile-formula-pricing/#developers) [Support](https://wordpress.org/support/plugin/hdwebmobile-formula-pricing/) ## Description HDWebmobile Formula Pricing lets customers enter measurements or quantities on the product page, and prices the product live from a formula you write using those field names (e.g. `10 + width * height * 0.05` for a custom-cut material priced by area). This is a common real need for stores selling custom-sized fabric, framed prints, engraved items, or anything priced by dimension or quantity, not just a flat number. #### Security by design The simplest way to implement formula-based pricing — passing the merchant’s formula text straight into PHP’s `eval()` at calculation time — is also the most dangerous: it turns any formula input into a remote code execution path. This plugin closes that entire vulnerability class by construction: * The formula is tokenized character-by-character into a strict set of allowed pieces: numbers, your own configured field names, and the four arithmetic operators plus parentheses. Anything else in the formula text — any other letter sequence, any function-call-looking pattern, any special character — causes the formula to be rejected outright when you save it. * The token stream is evaluated by a small hand-written arithmetic parser. There is no `eval()`, no `create_function()`, no dynamic function dispatch of any kind anywhere in this plugin — the only operations that can ever run are addition, subtraction, multiplication, and division of plain numbers. * The customer-facing live price preview also never exposes your formula to the browser: it’s computed by an AJAX call back to your own server, through the exact same safe evaluator used at checkout, so the formula text itself is never sent to a visitor’s browser. * The real price used at checkout is always recomputed server-side from the product’s own stored fields and formula — never trusted from what the browser submitted. #### Key Features * Add up to 6 numeric input fields per product (label, variable name, min/max bounds, default value) * Write a formula referencing those fields by name — validated for safety the moment you save it * Live price preview on the product page as the customer types, computed server- side * Optional minimum/maximum price clamps, so no combination of inputs can produce an unreasonable price * Every field’s min/max bounds are enforced again server-side at add-to-cart time, not just in the browser * Field values show on the cart, checkout, and order screens exactly as entered #### Limitations (please read before installing) * Simple products only in this version — no variable-product support * Formulas support only +, -, *, /, and parentheses (no exponents, square roots, or conditional logic) — deliberately, since a richer grammar is a larger safety surface to get right * No formula “test” button in the admin beyond the save-time validation — if a formula is rejected, the error message names exactly what’s wrong (an unknown variable, a bad character, division by zero with the values you tried) * Requires a Regular Price to be set on the product (even a nominal placeholder)— this is standard WooCommerce behavior for any product with no price at all, not something this plugin can work around #### Enjoying this plugin? If it helps your site, please consider [leaving an honest review on WordPress.org](https://wordpress.org/support/plugin/hdwebmobile-formula-pricing/reviews/#new-post)— it helps other WordPress users find it. Found a problem or have an idea? Please [open a support topic](https://wordpress.org/support/plugin/hdwebmobile-formula-pricing/) first so it can be fixed. ### How to Use #### 1. Add your input fields On a simple product’s “Formula Pricing” tab, click “+ Add Field” for each number the customer should enter (e.g. “Width in cm” with variable name `width`). Set a minimum, an optional maximum, and a default value for each. #### 2. Write the formula In the Formula box, write an expression using your field names exactly as shown, e.g. `10 + width * height * 0.05`. Save the product — if the formula uses anything other than your field names, numbers, and `+ - * / ( )`, you’ll see exactly what’s wrong and the formula won’t be saved until it’s fixed. #### 3. What the customer sees The product page shows your input fields above the Add to Cart button, with a live estimated price that updates as they type. The real price is confirmed the moment the product is actually added to the cart. #### 4. Keeping prices sane Set an optional minimum and/or maximum price on the same tab — no matter what a customer enters (within their allowed field ranges), the final price is clamped to stay within those bounds. ## Screenshots [⌊The Formula Pricing tab on a product's edit screen -- fields and formula configuration.⌉⌊ The Formula Pricing tab on a product's edit screen -- fields and formula configuration .⌉[ The Formula Pricing tab on a product’s edit screen — fields and formula configuration. [⌊The customer-facing input fields and live price preview on the product page.⌉⌊ The customer-facing input fields and live price preview on the product page.⌉[ The customer-facing input fields and live price preview on the product page. [⌊A cart line item showing the entered measurements alongside the computed price.⌉⌊ A cart line item showing the entered measurements alongside the computed price.⌉[ A cart line item showing the entered measurements alongside the computed price. ## Installation 1. Upload the plugin files to the `/wp-content/plugins/hdwebmobile-formula-pricing` directory, or install the plugin through the WordPress plugins screen directly. 2. Activate the plugin through the ‘Plugins’ screen in WordPress. WooCommerce must already be installed and active. 3. Edit a simple product, open its new “Formula Pricing” tab under Product Data, add your fields and formula. 4. On the product’s “General” tab, set a Regular Price — WooCommerce hides the entire purchase form on a product with no price at all, even with formula pricing enabled, so enter at least a nominal placeholder amount (it will be overridden the moment a customer enters a value). ## Reviews There are no reviews for this plugin. ## Contributors & Developers “HDWebmobile Formula Pricing” is open source software. The following people have contributed to this plugin. Contributors * [ HDWebMobile ](https://profiles.wordpress.org/htrxuan/) [Translate “HDWebmobile Formula Pricing” into your language.](https://translate.wordpress.org/projects/wp-plugins/hdwebmobile-formula-pricing) ### Interested in development? [Browse the code](https://plugins.trac.wordpress.org/browser/hdwebmobile-formula-pricing/), check out the [SVN repository](https://plugins.svn.wordpress.org/hdwebmobile-formula-pricing/), or subscribe to the [development log](https://plugins.trac.wordpress.org/log/hdwebmobile-formula-pricing/) by [RSS](https://plugins.trac.wordpress.org/log/hdwebmobile-formula-pricing/?limit=100&mode=stop_on_copy&format=rss). ## Changelog #### 1.0.0 * Initial release: per-product numeric input fields, safe formula evaluation via a hand-written tokenizer and recursive-descent parser (no eval()), server-side live price preview via AJAX, min/max price clamping, field values shown on cart/ checkout/order screens. ## Meta * Version **1.0.0** * Last updated **3 days ago** * Active installations **Fewer than 10** * WordPress version ** 6.9 or higher ** * Tested up to **7.1.3** * PHP version ** 7.4 or higher ** * Tags * [calculator](https://wordpress.org/plugins/tags/calculator/)[Custom Pricing](https://wordpress.org/plugins/tags/custom-pricing/) [dynamic pricing](https://wordpress.org/plugins/tags/dynamic-pricing/)[formula](https://wordpress.org/plugins/tags/formula/) [woocommerce](https://wordpress.org/plugins/tags/woocommerce/) * [Advanced View](https://wordpress.org/plugins/hdwebmobile-formula-pricing/advanced/) ## Ratings No reviews have been submitted yet. [Your review](https://wordpress.org/support/plugin/hdwebmobile-formula-pricing/reviews/#new-post) [See all reviews](https://wordpress.org/support/plugin/hdwebmobile-formula-pricing/reviews/) ## Contributors * [ HDWebMobile ](https://profiles.wordpress.org/htrxuan/) ## Support Got something to say? Need help? [View support forum](https://wordpress.org/support/plugin/hdwebmobile-formula-pricing/) ## Donate Would you like to support the advancement of this plugin? [ Donate to this plugin ](https://paypal.me/htrxuan/20)