Free browser extension
A hotel comparison website
that checks whether the cheaper listing names the same room.
To compare hotel prices across booking sites, look up one hotel and your dates on Google Hotels, which lists the booking sites side by side, then compare the totals with taxes and fees for the same room name and the same cancellation terms, and check the hotel's own site too. In our 17 price snapshots of September 22 to October 10, 2026 (7,044 hotel prices in 368 cities, for a US searcher in US dollars), some booking site listed the stay 5% or more below the going rate at 5,114 hotels (73%), but at 4,294 of those the lowest listing named no room.
Underbook compares hotel prices for your hotel and dates across the booking sites Google Hotels lists, and shows the prices side by side (all-in when the sites report taxes and fees), and whether the cheaper listing names the same room, so a lookalike room does not pass for yours. The free browser extension for Chrome, Edge or Firefox does this by itself on the hotel page you are already looking at, and you always book where you choose.
In numbers
- Some booking site listed the stay 5% or more below the going rate (the price most sites agree on) at 5,114 of 7,044 hotel prices (73%), typically 16.7% below.
- At 4,294 of those 5,114 (84%), the lowest listing named no room, so check the room before you book.
- Google Hotels listed a median of 17 booking sites per hotel, and Booking.com's public price was at or below every other site's at 846 of 4,729 hotels (18%), compared like with like.
Source: our hotel price study, 17 snapshots of September 22 to October 10, 2026 in 368 cities, Google Hotels' prices for a US searcher in US dollars; the last line uses our 14 price snapshots of September 25 to October 1, 2026, which kept every site. Method and per-hotel CSVs are on the study page.
Free · no account needed · we never see your payment info.
How hotel price comparison works with Underbook
Three steps, on the hotel page you are already on. Nothing to sign up for.
Book like normal
Search a hotel on the site you already use. Underbook stays out of the way until there's a reason to speak up.
It double-checks the rate
Underbook checks other booking sites for the same hotel, same dates, and same room, quietly, in the background.
You compare and decide
If a cheaper rate exists, you see the room name and cancellation terms next to what you were about to book. You choose where to book.
The catch with cheap hotel rates
A lower price only counts if it's the same room on the same terms. Booking sites are full of near-matches: a "city view" swapped for a "standard," a fully-refundable rate quietly replaced with a non-refundable one, a resort fee that only appears at checkout. A comparison that ignores those differences isn't lowering your price; it's changing your booking.
Underbook's whole job is to make the comparison honest. It compares the room names each site publishes and tells you whether the cheaper listing names the same room. When it can't confirm the two rooms are identical, it says so plainly and shows you both. It never pretends a lookalike is the same room to win a click.
What Underbook does
- Checks the same room, same dates
- Says whether the cheaper listing names the same room
- Tells you when a match is unconfirmed
- Free, no account needed
What it never does
- Book for you or hold your card
- Pass off a different room as a lower price
- Invent price gaps to get your click
- Sell your data
Which hotel comparison site actually gets you the lowest price?
We measured this rather than guessed. Recording 7,044 hotel prices in 368 cities on every booking site Google Hotels lists (17 snapshots, September 22 to October 10, 2026), two patterns held. First, a lower listing is common: at 73% of hotels some site was 5% or more below the going rate, typically 16.7% below, and the big names hold rate parity less tightly than advertised: on the same tax footing, Expedia and Booking.com were within $2 a night at 59% of the 3,056 hotels where both could be compared, in our 14 price snapshots of September 25 to October 1, 2026. Second, the lower listing rarely proves it is your room: at 4,294 of 5,114 hotels with one, the lowest listing named no room, and in our 14 price snapshots of September 25 to October 1, 2026, a lower listing whose room name matched turned up at 515 of 5,830 hotels (8.8%) on our original room check (952, or 16.3%, on the stricter October 1 check), strong evidence but not proof.
Even Booking.com, the site Google Hotels listed most, was at or below every other site at only 18% of the hotels where its price could be compared like with like, in our 14 snapshots of September 25 to October 1, 2026: does Booking.com have the cheapest prices? To compare on the page you are already on, browser extensions do it for you: which ones, side by side, and if you use Hotel Ninja, its alternatives.
So the comparison worth using shows you the all-in price where the sites report taxes and fees, includes the smaller sites the big ones leave out, and tells you plainly when the lower listing does not name the same room. A comparison that hides the fine print does not lower your price; it changes what you book.
The comparison sites travelers name, side by side
What each one says about the prices it shows, from its own help, about or terms pages, read on October 6, 2026: whether taxes and fees are in the price, what it says about the room, whether the hotel's own site is among the offers, and how it is paid. Where its pages say nothing, the table says so. They can change, and a correction is welcome.
| Site | What it compares | Taxes and fees in the price | The room | The hotel's own site | How it is paid |
|---|---|---|---|---|---|
| Google Hotels | Prices from its hotel, online travel agency and metasearch partners; free booking links ranked by their use to you, paid ads marked "Ad" | In the US and Canada, the total shown first includes the base rate and mandatory non-governmental fees, and choosing "Nightly price" also shows a "Nightly total" with taxes and fees; elsewhere, the total with taxes and fees | May show room details such as maximum occupancy or bed type | A link to the hotel's website on its page; in our data the hotel's own site was among the prices at 3,908 of 5,830 hotels (67%) | Ads by auction; free booking links cost partners nothing, and Google's commercial relationship with a partner has no effect on their order, it says |
| KAYAK | Hotel prices across hundreds of travel sites, well-known online travel agencies and smaller sellers | Its help says flight and car prices include taxes and fees; it does not say so for hotels | Not stated on its help pages | Results from hotels as well as online travel agencies, its about page says | Commissions from partners, per click or per booking, and ads; part of Booking Holdings |
| trivago | Offers for hotel rooms from "100s of sites", from hotels directly or through online travel companies, its terms say | Prices are per night (the average for a longer stay) and a provider's price may differ from the one shown, its terms say; they do not mention taxes | Not stated in its terms | Offers can come directly from a hotel, its terms say | Not stated on the pages we could read; its help center refused our reader |
| Skyscanner | Thousands of sites for flights, hotels and car hire | Prices "always include an estimate of all taxes and charges", travel agencies' fees included, its help says | Not stated on its help pages | Not stated on its help pages | A referral fee from the travel company you book with |
| momondo | Hundreds of travel sites, from major booking sites to individual company sites | It tries to include all mandatory fees and surcharges, and advises checking the final price on the booking page | Not stated on its help page | Prices come from suppliers such as online travel agents and the hotel's own site | Referral fees per booking or click, and ads; a hotel's offers are ordered by clicks, price and what the site pays per click, with the lowest price marked in green when it is not on top |
| HotelsCombined | Hundreds of other travel sites at once | Its help answer on taxes and fees covers flights, trains and buses, not hotels | Not stated on its help page | Not stated on its help page | Not stated on its help page |
| Tripadvisor | Prices from partners; it is not a booking agent, its press center says | Check the partner's site for a full disclosure of all applicable fees, its press center says | Not stated; tripadvisor.com and its help center refused our reader | Not stated | Not stated |
| Vio | Hotel prices across 100+ travel sites, its own included; sometimes you book with Vio, sometimes with a partner | It says it shows what is included and how much you will pay, before you book | Not stated on its How Vio Works page | Not stated on that page | Not stated on that page; Vio also takes bookings and payment itself |
| Underbook | Every booking site Google Hotels lists for your hotel and dates, a median of 17 per hotel in our data | All-in where the sites report taxes and fees (at 4,062 of 5,830 hotels, 70%, in our data); otherwise the listed rate, marked as such | Says whether a lower listing names the same room, and to check when it does not | Included when Google Hotels lists it | May earn a commission if you book through its link, which never changes the order of prices |
Sources, read October 6, 2026: Google's help pages "Search for hotels on Google", "About hotel free booking links" and its Taxes and Fees Policy; KAYAK's help pages on search, pricing and the company; trivago's home page and terms of use; Skyscanner's help articles on what its prices include and why it is free; momondo's help page; HotelsCombined's help page; Tripadvisor's US press center; vio.com/how-vio-works. KAYAK and momondo each say they are part of Booking Holdings. In our 14 price snapshots of September 25 to October 1, 2026, HotelsCombined's price on Google Hotels was KAYAK's at all 1,045 hotels listing both (is HotelsCombined legit?). If you book through Underbook we may earn a commission, which never changes which rate we show.
How to compare hotel prices the right way
A genuine hotel room comparison lines up four things, not just the headline nightly rate:
- 1. The same room. A "city view king" is not a "standard queen." Confirm the room name matches before you compare prices.
- 2. The all-in total. Compare the price with taxes, resort fees, and cleaning fees included. A lower base rate with a hidden resort fee often costs more at checkout.
- 3. The cancellation terms. A cheaper non-refundable rate is a different product than a refundable one. Compare like for like.
- 4. The same dates and occupancy. Prices swing by date and guest count, so hold those constant across every site.
Doing all four by hand for every booking is tedious enough that almost nobody does it. That is exactly the job Underbook automates: it compares hotel prices for your hotel and dates across sites on an all-in basis and flags whether the lowest-priced listing names the same room or is an unverified lead to check.
Measured, September 25 to October 1, 2026
How the big booking sites' prices sat against the going rate
In our 14 price snapshots of September 25 to October 1, 2026 we recorded 5,830 hotel prices in 348 cities on every booking site Google Hotels lists. Each big site's price against the going rate (the price most sites agree on), compared like with like; the percentages are of the hotels where that could be read (KAYAK is a comparison site, and its price was often before tax):
| Site | Hotels listed | Within 2% of the going rate | 5% or more below | Named a room |
|---|---|---|---|---|
| Booking.com | 5,264 | 63% | 5% | 87% |
| Expedia.com | 3,996 | 91% | 2% | 92% |
| Hotels.com | 4,433 | 79% | 6% | 86% |
| Priceline | 4,380 | 64% | 5% | 38% |
| Agoda | 3,434 | 60% | 13% | 51% |
| Trip.com | 2,409 | 53% | 9% | 11% |
| KAYAK | 1,679 | 40% | 15% | 0% |
Some site was 5% or more below the going rate at 4,181 of 5,830 hotels (72%). At 3,323 of them (79%) the lowest listing was on none of these seven sites, most often on Super.com (1,123 hotels), Vio.com (449) and Traveluro (305). At 3,479 of them (83%) the lowest listing named no room.
So the big sites mostly agree with each other, and the lower prices sit on sites many people never open, usually without saying which room they sell. A comparison is worth as much as the sites it covers and how plainly it shows the room.
Each snapshot: US market, USD, prices from one moment for a two-night stay, not completed bookings. "Like with like" means before tax against before tax and all-in against all-in, inferred from the hotel's two going rates; hotels where that could not be read are left out. Method, charts and the per-hotel CSVs: the hotel price study.
Hotel price comparison: common questions
How do I compare hotel prices across booking sites?
Look up one hotel and your dates on Google Hotels, which lists the booking sites side by side, then compare the totals with taxes and fees for the same room name and the same cancellation terms, and check the hotel's own site too. A lower listing is common and often names no room: in our 17 price snapshots of September 22 to October 10, 2026, some booking site listed the stay 5% or more below the going rate at 5,114 of 7,044 hotel prices (73%), and at 4,294 of those the lowest listing named no room. Underbook's free browser extension and web price checker show each booking site's Google Hotels price for your hotel and dates and say whether a lower listing names the same room.
What is the best hotel comparison website?
No single booking site had the lowest price everywhere: in our 14 price snapshots of September 25 to October 1, 2026, Booking.com's public price was at or below every other site's at only 846 of 4,729 hotels (18%), compared like with like. Look for one that shows the price with taxes and fees where the sites report them, includes the smaller sites as well as the big ones, and says whether a lower listing names the same room. Underbook is a free browser extension that does this for the booking sites Google Hotels lists for your hotel and dates. It sees only the public prices those sites list there, not member prices or sites Google Hotels leaves out, and a matching room name is not proof of the same room.
Are hotel comparison sites accurate?
The nightly rate they show is usually accurate, but it can be misleading. Many hotel comparison sites rank listings by commercial factors, quote a base rate before taxes and resort fees, and compare a cheaper room against the one you actually want. When we recorded 7,044 hotel prices from September 22 to October 10, 2026, the lowest listing named no room at 4,294 of the 5,114 hotels where some site was 5% or more below the going rate. So treat the headline number as a starting point, then confirm the room, all-in total, and cancellation terms before you book.
How do I compare hotel prices for the same room?
The trap is comparing a cheaper rate that's really a different room or a non-refundable version. Underbook shows the price each booking site lists on Google Hotels for your hotel and dates, says whether a lower listing names the same room and whether it shows free cancellation, and says to check before booking when the room names don't match. A matching room name is strong evidence, not proof, so read the room and the cancellation terms on the site before you book.
Why is the same room cheaper on a site I've never heard of?
Lesser-known booking sites buy rooms through different wholesale channels and spend less on advertising, so their listed rates are sometimes lower. Not always the identical room, though, which is exactly why Underbook tells you whether the cheaper listing names the same room, so you can check before you book.
Does it cost anything?
No. Underbook is a free browser extension. If you book through a site it surfaces, it may earn a small commission from that site; you pay nothing extra, and it shows the lower rate even when its commission would be smaller.
Is my data safe?
When you open a hotel page, Underbook sends the hotel name, your dates and your party size to its price service to look up current rates. Nothing that identifies you goes with it. It never sees or stores your payment details, booking happens on the site you choose, and it doesn't sell your data. Read the privacy policy →
Which sites a comparison covers
Google Hotels listed a median of 17 booking sites per hotel in our snapshots: which booking sites Google Hotels shows. Some of them are one company with one price: the sites Expedia owns.
Real prices, hotel by hotel
Every site's price at 5,970 hotels in 368 cities
From our price snapshots of September 25, 2026, September 28, 2026, September 29, 2026, September 30, 2026, October 1, 2026, October 3, 2026 and October 10, 2026: each hotel's page lists every booking site Google Hotels showed, the going rate, and whether the lowest-priced listing named a room, with a button to check today's price for your own dates.
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