Most WordPress sites in 2025 are still running on a purchased theme with forty settings nobody understands and a page builder fighting the theme for control of the layout. A custom theme, built for the specific site rather than for a marketplace audience, is a different proposition entirely — and it's worth understanding what you're actually paying for when you commission one.
Why a purchased theme becomes a liability
Marketplace themes (ThemeForest and similar) are built to demo well across thousands of possible use cases, which means they ship with enormous amounts of CSS and JavaScript your site will never use. It's common to find a purchased theme loading 800KB–1.5MB of unused CSS on every page load — a direct hit to Core Web Vitals and mobile performance. They also tend to bundle a page builder (Elementor, WPBakery, Divi) as a dependency, which means your entire site becomes unportable: strip out the builder and every page turns to a wall of shortcodes.
What a custom theme build actually includes
A properly scoped custom WordPress theme engagement covers:
- A component library built in Advanced Custom Fields (ACF) or the native block editor, so content editors assemble pages from a defined set of blocks rather than an open canvas
- A starter theme foundation (commonly Sage/Roots with Blade templating, or a lean underscores-based build) rather than a general-purpose framework, keeping the codebase to what the site actually needs
- Design tokens matching the brand's design system — colour, type scale, spacing — implemented as CSS custom properties so future design changes don't require touching templates
- Editor experience work: custom block patterns, sensible default content, and field descriptions so non-technical staff can publish without guessing
Performance numbers worth targeting
For a marketing-led WordPress site, we set these as minimum bars for a custom theme build:
| Metric | Target |
|---|---|
| Largest Contentful Paint | Under 2.0s on 4G |
| Total CSS payload | Under 150KB compressed |
| Total JS payload (excluding forms/analytics) | Under 100KB compressed |
| Lighthouse Performance score | 90+ on mobile |
These are achievable with a custom build because you control every line of CSS shipped; they're rarely achievable on a stock marketplace theme because you're paying the tax of features you didn't ask for.
Choosing a development partner: questions that actually matter
When evaluating a WordPress theme partner for a 2025 project, the questions that separate a serious shop from a theme reseller:
- Do you build on a starter theme or a page builder? (Page-builder-first answers are a red flag for long-term maintainability.)
- How do you structure custom fields so content stays portable if we ever migrate off WordPress?
- What's your approach to accessibility — do components meet WCAG 2.2 AA out of the box, including keyboard navigation and focus states?
- How do you handle the block editor vs. ACF Blocks vs. a page builder, and why?
- What does your QA process look like across browsers and screen readers before launch?
Budgeting for a purpose-built theme
A custom WordPress theme for a mid-size marketing site (15–40 templates, a handful of custom post types, ACF field groups for structured content) typically runs $18,000–$35,000 CAD, with ongoing theme maintenance and WordPress core/plugin updates in the $400–$1,200 CAD/month range. That's a real premium over a $60 marketplace theme, but it buys you a site that loads faster, is easier for your team to edit correctly, and doesn't lock your content into a page builder's proprietary shortcode format.
Thinking about moving off a bloated theme in 2025? Tell us which theme you're on now and we'll give you a straight read on what a custom rebuild would look like for your site.
Surrey, BC
A full-service digital agency working in WordPress, Drupal, Shopify, Webflow, React, and React Native. We partner with universities, governments, and growing brands to ship sites and products that hold up after launch.
