How it works
From a shelf tag to a number you can compare.
This page is the full explanation: where the prices come from, what happens to them before you see them, what the ranking is based on, how to get a good answer out of it, and how the site pays for itself. If you are going to rely on a number, you should know how it was made.
Last reviewed August 21, 2026 · written and maintained by Ashley Douds
What happens between your search and the grid
Three steps, with the part I care about most in the middle. Click through when you have a minute.
Where the numbers come from
Chains publish prices and promotions for their own sites and apps. That is how a shopper sees a 2 for $5 without asking anyone. Smopper reads that published pricing, along with weekly flyers, for the stores it covers.
Collection happens on a schedule rather than at the moment you search, which is why the results come back quickly. It also means a price can trail the shelf by a few days, so treat what you see as a strong starting point rather than a guarantee.
When a feed breaks or a listing is written so loosely that no honest reading produces one number, that row stays empty. I would rather hand you a gap than a number I made up.
Step 1 of 3
What gets collected, and when
Example of a collection schedule. Cadence varies by chain.
| Chain | What I collect | Checked |
|---|---|---|
| Aldi | Shelf prices, weekly specials | Weekly |
| Giant Eagle | Shelf prices, digital coupons | Weekly |
| Kuhn's Market | Shelf prices, printed flyer | Weekly |
When a price cannot be confirmed
That row stays empty and sits out of the totals. It does not get filled with the last number I saw.
Collection runs on a schedule rather than at the moment you search, so the screen is already built when you ask for it. The trade is that a price can be a few days behind the shelf.
The same jar, four times
Here is one listing moving through the four stages, shown as the data rather than as a diagram of the data. It cycles on its own; hover or tab into it to stop, or click a stage to jump.
Stage two is where most of the difficulty lives. Sizes arrive written every way a marketing department can think of, and until they are parsed into a number and a unit there is nothing to compare.
The figures in this example are illustrative. For real numbers, run a comparison in the compare tool.
One listing, start to finish
Worked example with sample figures. Hover or focus to pause.
What the stores hand over
Three formats, three ways of writing a size, one of them in millilitres
[
{ "store": "Aldi", "item": "Pasta sauce", "size": "24 oz", "price": "$1.85" },
{ "store": "Giant Eagle", "item": "Pasta sauce", "size": "2 x 16 oz", "price": "$5.49" },
{ "store": "Kuhn's", "item": "Pasta sauce", "size": "680 ml", "price": "$3.29" }
][
{ "store": "Aldi", "item": "Pasta sauce", "size": "24 oz", "price": "$1.85" },
{ "store": "Giant Eagle", "item": "Pasta sauce", "size": "2 x 16 oz", "price": "$5.49" },
{ "store": "Kuhn's", "item": "Pasta sauce", "size": "680 ml", "price": "$3.29" }
]Four rules I hold to
These are deliberately blunt so you can hold me to them. If you catch Smopper breaking one, that is worth an email.
No paid placement
A store cannot pay to appear higher. Order follows the unit price for your search and your area, and there is no product on this site for a retailer to buy.
No invented prices
If a feed breaks or a listing is too ambiguous to read one number out of, the row stays empty. A gap is more useful to you than a confident guess.
No fake equivalents
Two products are only matched when they are a swap you would actually make. Filling a comparison row with something merely similar would make the totals meaningless.
No selling your data
Your basket, your searches, and your area are not sold to retailers or anyone else. What the site does collect is spelled out in the privacy policy.
Getting the most out of it
A few habits that turn a comparison into money you keep. None of them take longer than a minute.
Try it on your list- 01
Start with the staples
Milk, eggs, bread, coffee, the cereal your kid will actually eat. Packaged goods you buy every week are where Smopper is strongest, and a few cents an ounce on those compounds into real money across a year.
- 02
Read the unit price, not the tag
The per-ounce or per-count number is the one that tells you what you are paying for. Once you have looked at a few, the tag stops fooling you and the whole trip gets easier.
- 03
Try the store-brand swap
Store brands are matched to the name brand they stand in for, so you can see the gap on a swap you would genuinely make. This is usually the single biggest win on a weekly list.
- 04
Treat a few cents as a tie
Prices are collected on a schedule, so a very close call can come down to which day the shelf changed. When two stores land within a few cents, take the one you were driving to anyway.
- 05
Come back and re-run the same list
Prices are kept as they are collected, so running your list again in a month shows you what actually moved. That is where most of the writing in Smopper Insights starts.
How this pays for itself
Servers, price collection, and the hours it takes to keep the data current all cost something, and the site is free to use. Here is the arrangement in plain terms.
Smopper carries display advertising, served by third-party ad networks. Those ads are what keep the comparison tool and the blog free, and they are separated from the content so you can always tell which is which. An advertisement is never presented as a price result.
Advertising buys nothing else. It does not affect which store ranks first, which products get matched to each other, which chains get added next, or what I write about in Smopper Insights. There are no affiliate links in the rankings and no sponsored posts.
Ad networks may use cookies to select what they show you. What gets collected, and how to opt out of personalised advertising, is set out in the privacy policy.
When something is wrong
Send the item, the store, and what the shelf actually said. Corrections go to the same inbox as everything else and I read all of it. If a post turns out to be wrong I fix the post rather than leaving it up looking authoritative, and if a price is wrong the fix usually helps everyone shopping that chain, not just you.
Questions people actually send
- Where do the prices come from?
- From the pricing chains already publish for their own websites and apps, plus weekly flyers. That information is collected, cleaned, and converted to a common unit before it appears here. Nothing is scraped from a competitor's comparison site, and no prices are estimated.
- How fresh is the data?
- Prices are refreshed on a schedule rather than at the moment you search, and the cadence varies by chain and category. That keeps results fast, but it means a price can be a few days behind the shelf. Treat a close call as a tie and check the tag.
- What should I do if a price looks wrong?
- Send it through the contact page with the item, the store, and what you saw on the shelf. Those messages go to the same inbox Ashley reads. A single correction often exposes a feed problem affecting everyone shopping that chain, so they are genuinely worth sending.
- Why is the store I shop at missing?
- Because coverage only expands where the data can be kept honest. Adding a chain badly is worse than not adding it, since it would put unreliable numbers next to reliable ones. Requests through the contact page are the main thing that decides what gets added next.
- How does Smopper make money?
- Display advertising on the site and the blog, which covers hosting and the time it takes to keep the data current. Smopper takes no affiliate fees and no payment from retailers, and advertising has no influence on rankings, product matching, or what gets written about in Smopper Insights.
- Is Smopper owned by a grocery chain?
- No. It is independently run by Ashley Douds, has no retailer investors, and no chain has any say in what appears here.
Something not covered here? Ask me.
The fastest way to understand it is to use it.
Put in five things you buy every week. The explanation above will make a lot more sense next to your own numbers.
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