How we rank
Everything starts with real price per GB
Price per GB is the plan price divided by the data you get. A $20 plan with 20 GB costs $1.00 per GB. A $10 plan with 3 GB costs $3.33 per GB, so the cheaper sticker is the worse deal. Sellers push labels like unlimited, best value, or special offer. The maths cuts through all of it.
One refinement keeps that number honest: we only count data you could actually use inside the validity, at most 3 GB a day, which is the heavy use figure in our own data guide. A 50 GB plan that lasts 3 days is priced on 9 GB, because nobody burns 50 GB in a long weekend. A 50 GB plan that lasts 30 days is priced on all 50. So a huge pool on a short validity, the oldest trick for a flattering per GB rate, cannot buy the top of the table. The table shows this usable rate, and the seller's own sticker maths is kept for reference.
Every table on this site is sorted by that number, lowest first, with one rule for fairness: every provider's best two plans come first, then everyone's remaining plans in the same order. A seller with a grid of forty near identical plans still ranks by its prices, but it cannot fill the whole first screen. Plans with no fixed data amount, such as unlimited plans, cannot be ranked by price per GB, so they sort after the fixed plans and we explain their fair use limits in the page content instead.
And one rule for suspicion: a plan we have not yet verified on the seller's own site, priced at under half of every other provider's best rate on that page, is held back at the end of the ranked plans and marked Unverified price. Too good to be true is not a recommendation. The moment our checker, or a person on our team, has seen that price on the seller's site, it competes like any other plan.
The same three plans, two ways of looking at them:
What the sticker says
Plan A looks cheapest.
What you actually pay per GB
Plan B is the real winner. Plan A costs over three times more per gigabyte.
Where the prices come from
Prices come from provider catalogues through automated feeds, not from typing numbers in by hand. Each sync recalculates every price per GB and rebuilds every ranking. Each page shows the exact date and time of the latest check in GMT. When a price changes at the source, the site changes with it.
How the Watchdog Pick is chosen
The pick on each country page is chosen by one rule: the lowest real price per GB of the plans in your current view, counting only plans sized for a trip. A 500 GB pool sold for a few days has a very low price per GB on paper, but that rate depends on using data nobody uses on holiday, so pools above 50 GB are listed and priced honestly without being allowed to win the pick. Change the filters and the pick recalculates. Providers cannot pay for that spot, and it changes the moment a cheaper plan appears. When our own listed partners are beaten on price, the table shows it.
What the verdict tags mean
Each plan gets a tag based on how far its price per GB sits above the cheapest plan on the page. The tags are computed, not chosen:
The percentages measure the gap above the cheapest rate on the page. A plan within five percent of the best price per GB earns Best value. A plan costing several times the best rate earns Very expensive, no matter whose logo is on it.
What we earn and what it cannot do
Some links are affiliate links. If you buy through one, the provider may pay us a small commission at no extra cost to you. Commissions never touch the ranking logic. There is no field in our database for "paid us money" because the ranking code would have nowhere to read it. The full detail is on our affiliate disclosure page.
What we do not do
We do not run speed tests in every country, so we describe networks and coverage from sourced facts rather than claiming measurements we did not make. We do not list every seller on earth, only catalogues we can check properly. And we do not publish a user review until a human has read it. If something on this site is wrong, tell us at hello@esimwatchdog.com and we will fix it.