The cheapest day to fly, from a Google Flights price calendar in Google Sheets

Google Flights shows a price calendar, but you cannot sort it, keep it or compare two routes. In Google Sheets you can. Two ways, both free to try.

Way 1: the fare calendar from the menu (one result)

Install SheetSonar, then Extensions › SheetSonar › Get a free key. No sign-up, no card.
Open Extensions › SheetSonar › Fare calendar… and type the route and the period, separated by semicolons: JFK ; LHR ; 2026-11-01 ; 2026-12-31 ; 7. The last number is the trip length in days; leave it out for a one-way.
A new sheet appears with one row per departure day: departure, return, lowest price, currency, and a Cheapest mark on the best day of the whole period.

Up to a year of dates in one go, and the whole calendar counts as one result on your plan. Sort the Lowest price column, add a line chart, or copy the sheet to keep today's prices.

Way 2: one formula per date (to compare routes or keep a history)

When you want the calendar to recalculate by itself, or to put two routes side by side, use the formula with a column of dates:

Departure     | CDG → JFK                        | LHR → JFK
=TODAY()+30   | =SONAR_FLIGHT("CDG","JFK",A2)    | =SONAR_FLIGHT("LHR","JFK",A2)
=A2+1         | =SONAR_FLIGHT("CDG","JFK",A3)    | =SONAR_FLIGHT("LHR","JFK",A3)
…             | …                                | …

Then Format › Conditional formatting on the price columns with a colour scale: the cheapest days turn green on their own. Each cell is one result, so 14 dates on one route is 14 results: fine for the free plan once in a while, or every day on Pro. The flight price tracker template shows how to keep a history, one column per day.

Which way to use

Looking for the one cheapest day on a long period: the menu, one result for up to a year.
Comparing two or three routes or watching the same two weeks every day: the formula.
Flexible return: run the menu calendar twice with two trip lengths (; 7 then ; 10) and compare the two sheets.
Several airports: PAR for all Paris airports, LON for London, or JFK+EWR.

What it costs

The free plan gives 20 results a month. A menu calendar is one result whatever its length; a formula cell is one result per route and date, kept for 3 hours. Pro gives 1,000 results a month for €9.90. Plans.

Install SheetSonar Flight price tracker template

Prices come from the public Google Flights pages at the time of the search and can change before you book. Always check the final price with the airline or Google Flights.