Why the price you see can change: cached vs live travel prices

The price you see on a comparison site or in a price alert is often a cached price: a price that was recently seen by a system or another traveller, stored, and shown to you later. The price on the booking site is the live price, checked at that moment with the airline, hotel or travel agency. Because fares and rates change constantly, the two can differ. The live price on the booking site is always the one you actually pay.

This guide explains what cached and live prices are, why services use both, and what to do when the price changes.

What is a cached price?

Checking a live price for every possible flight or hotel is slow and costly for travel systems. To make searching fast, many data providers keep a cache: a large store of prices that were recently found for particular routes, dates and hotels. When you search, you may be shown prices from that store instead of a fresh check.

Cached prices are a good guide to what a trip costs. Their weakness is age. A cached price might have been seen a few minutes ago, a few hours ago or, in some cases, a day or two ago. In that time, seats may have sold, a hotel may have changed its rates, or a sale may have ended or started.

What is a live price?

A live price is checked at the moment you look, directly with the airline, hotel or travel agency that would sell it to you. It reflects current availability. That is what you see when you click through to a booking site and select a flight or room.

Even a live price can change between viewing and paying, for example if the last seats at that price are bought by someone else during your booking.

Why the price can be different

Common reasons the live price differs from the price you saw:

• Time has passed. The cached price is older than the live one, and prices moved.
• Seats or rooms sold out. The cheapest option was limited and has gone.
• Different details. The live search might include different baggage, a different room type, or taxes and fees that were not in the earlier price.
• Currency conversion. If the price was converted, exchange rates and the booking site's currency handling can change the figure.
• Different seller. The same flight or room can be sold by several sites at different prices.

The difference can go either way. Sometimes the live price is lower than the one you were shown.

How Trigger handles this

Trigger uses official data partners only and does not scrape websites.

• Flight prices come from the Travelpayouts network through Aviasales. Hotel prices come from the Travelpayouts network through Hotellook. These partner prices are often cached, recently seen prices. They can be hours to around two days old.
• For some hits, Trigger also checks Google travel results through SerpApi to confirm the price live before emailing you.
• Every alert email links to a trusted partner site, where you see the live price before you book.

Trigger cannot guarantee availability or price. Trigger does not sell travel or take payments, so the price and terms on the booking site are what apply. You can read more in our price disclaimer.

What to do when the price has changed

1. Check the details match. Make sure dates, passengers or guests, cabin or room type and filters are the same as your alert.
2. Look at nearby options. A similar flight on the same day or a similar room may still be close to the alerted price.
3. Compare the total. Include bags, seats, taxes and fees.
4. Decide quickly but calmly. If the live price still meets your budget, booking soon reduces the chance of it rising further. If not, there is no need to book. Your alert keeps watching.
5. Keep your alert running. Trigger keeps checking until the travel date and will email you if the price drops at least 5% below the last price you were emailed about, at most once a day.

Why check frequency helps

Since prices move between checks, how often a service looks matters. Trigger checks more often as the travel date gets closer: about every 12 hours for trips more than 60 days away, every 6 hours for 15 to 60 days, every 3 hours for 4 to 14 days, and hourly in the last 3 days. Alerts whose last price was within 10% of the target are checked one step faster. That reduces, but cannot remove, the gap between a price appearing and you hearing about it.

How to set a Trigger for it

1. Search on flights or hotels with the exact details you want.
2. Set a realistic target price. See how to set a realistic target price.
3. Create the alert. When the price is at or below your target, Trigger emails you immediately with a link to the partner site.
4. Open the link soon and check the live price before booking.

Trigger is free, with up to 10 active alerts. For the full picture, see how flight price alerts work and how it works.