Disney Math — a true trip cost calculator
A Chrome browser extension that recomputes the real cost of a theme park trip while you shop.
01 Summary
Disney World's advertised prices are structurally incomplete. A resort room quotes a nightly rate before tax; tickets quote a per-day price that only applies at the longest stay lengths; the line-skipping product (Lightning Lanes), dining plans, daily expenses, special event tickets, and annual pases are all separate purchases made on separate screens, days apart.
The result is a planning process where families cannot answer the only question they actually have — what will this trip cost? — until they have already committed to most of it. Disney Math sits on top of the pages people already browse and keeps a running, realistic total: every line item, every fee, every add-on, expressed in the units a family can grapple with.
02 The problem
Price fragmentation isn't a bug in Disney's booking flow — it's the design. Each surface quotes the smallest defensible number, and the gap between that number and the final one is large enough to change the decision. Planning a trip involves spreadsheets and a lot of research. It can be incredibly daunting for a first-timer trying to plan a magical family vacation - and the true cost can be difficult to grok from hotel or package pricing alone.
For more experiences Disney trip planners, being able to compare dates and structure split stays to minimize spend is a useful tool. And many Disney trip planners simply enjoy the trip-planning exercise.
The existing solutions are all pre-trip planning tools — you leave the booking flow, go somewhere else, model your trip, and come back. Almost nobody does this. The unmet need is for the true number to appear where the decision is being made, without the shopper changing what they were already doing. That's an extension, not a website.
03 Why now
- Date-based ticket pricing made costs genuinely hard to compute. Prices now vary by arrival date and trip length, so no static "a ticket costs $X" answer exists — which is precisely the condition under which a calculator earns its keep.
- Paid line-skipping is now a standard purchase. but it cannot be bundled with the initial purchase. The extension allows the planner to budget for lightning lane purchases ahead of time.
- Bundled services have been unbundled. Airport transfer, once included, is now a separate vendor decision — one of several costs that moved from invisible-and-free to invisible-and-expensive.
- Price sensitivity is high and public. Cost is now the dominant theme in coverage of and conversation about the parks, which means the framing needs no education.
04 Users
| Segment | Situation | What they need |
|---|---|---|
| First-timer | Planning a once-in-a-decade trip. Has a budget number in mind, no idea if it's realistic. | An early, honest total — before emotional commitment, not after. |
| Returning family | Been before, going again, watching costs more carefully this time. | Marginal comparisons: is the hopper worth it, is the deluxe resort worth it. What about a split-stay to bring the nightly average down? |
| Deal hunter | Comparing Disney direct against authorized resellers and package vendors. | Normalized totals so two offers are actually comparable. |
Primary for v1: the first-timer. Highest pain, least existing tooling, and the clearest moment of need. The other two are follow-on.
05 Goals and non-goals
Goals
- Show a complete, running trip total on the pages where trips are actually priced.
- Make every added line item legible and attributable — no black-box number.
- Express cost in per-person-per-day, the unit families actually budget in.
- Be trustworthy enough that a user would quote our number to their spouse/partner.
Non-goals for v1
- Itinerary or ride planning.
- Booking or transacting. We annotate; we don't sell - potential to affiliate with a travel agent
- Parks beyond Walt Disney World. Depth first.
- Mobile. The extension surface is desktop; a large share of research still happens there.
- Predicting discounts or forecasting future prices - some pricing requires maintenance (e.g. dining plan pricing). Affiliation with a travel agent would make sense here.
06 V1 scope
The overlay
A small persistent panel with selectable options showing the running total, collapsible to a single figure. It reads what's on the page — room rate, ticket configuration, dates, party size — and adds the costs the page omits. No account required, no data leaves the device. The extension browses behind the scenes, acting like a user.
The trip model
A lightweight local record of the trip as the user assembles it across sessions: dates, party composition, resort, ticket type, add-ons chosen. This is what turns per-page annotations into a running total, and it's the piece that makes the product sticky.
The estimate for what can't be read
Food is the largest unpriced cost and cannot be scraped from a booking page. V1 ships a transparent estimator — a per-person-per-day range by dining style, adjustable by the user, always labeled as an estimate rather than folded silently into the total. Getting this labeling right is the difference between a trusted tool and a discredited one.
The comparison
One derived view: what changes if a single variable changes. Drop a night. Skip the hopper. Move down a resort tier. This is where the product converts from an informational overlay into something that changes a decision.
Everything above is in service of one job: making the true number appear at the moment of the decision. The extension does not offer any reviews or randkings of the resort or dining experiences.
07 Success metrics
| Layer | Metric | v1 target |
|---|---|---|
| Activation | Installs that reach a first complete trip total | > 40% |
| Engagement | Users returning across 2+ sessions (planning is multi-session by nature) | > 35% |
| Core value | Users who open the itemized breakdown, not just the headline number | > 50% |
| Decision impact | Users who run at least one comparison | > 25% |
| Trust | Uninstall rate within 7 days | < 20% |
| Lead generation | If affiliating with a travel agent, how many leads are generated | < 3% |
08 Risks
The name is a liability
"Disney" is aggressively protected, and an extension store listing carrying it invites takedown regardless of the merits of nominative fair use. The product ships under a non-infringing name; "Disney Math" survives internally, as a working title only. Affiliating with a Disney travel agent is key to legitimizing this extension.
The host site can break or block us
We depend on reading pages we don't control. Markup changes silently break parsing; terms of service may prohibit automated extraction. Affiliation with a travel agent as a lead-generation tool potentially mitigates this risk.
Broad page access is a real ask
An extension that reads travel pages is asking for meaningful permission at exactly the moment users are most wary of extensions. Request the narrowest host permissions that work, keep the trip model local by default, and say so in the install flow. Do not require log-in by the user to estimate the trip.
09 Open questions
- Does the running total produce anxiety and an uninstall?
- Is a browser extension the right vessel, given that install friction is the highest of any consumer surface?
- How much of the total can actually be read from the page versus estimated/maintained externally?
- Does this generalize? The same fragmented-pricing problem exists in cruises, resorts, and event ticketing. Whether v1 is built as a Disney-shaped tool or a general true-cost engine with a Disney first vertical is a decision that gets expensive to reverse later.
10 Sequencing
| Phase | Work | Exit criteria |
|---|---|---|
| Validate | Prototype the overlay against static page captures; eight moderated sessions with first-time planners. | Evidence the total changes a decision, not just a mood. |
| Prove | Single page type end to end — resort rate → true nightly. Nothing else. | Parsing holds for four consecutive weeks without manual repair. |
| Complete | Tickets, add-ons, trip model, food estimator, comparison view. | A full trip is priced accurately end to end. |
| Launch | Store listing under final name, permission flow, accuracy feedback loop. | Activation above target; complaint rate below counter-metric. |