Compare grocery unit prices to catch shrinkflation and fake bulk deals

Unit prices (per ounce, per count) show the real cost. AI can turn a photo or list of shelf tags into a cheapest-per-unit ranking.

Real exampleNone verified yetGuide + prompt only.

Cost Free option availableYou can do this for $0. Some tools offer paid upgrades you don't need.

Time (estimate)5–10 min

Difficulty (estimate)EasyOne sitting, no special knowledge needed.

1. Copy this prompt

Paste it into ChatGPT, Claude, Gemini or Grok (the free versions work), then replace the [highlighted brackets] with your details. Leave out account numbers and SSNs.

Here are products and prices from [STORE(S)]: [LIST: PRODUCT, SIZE, PRICE, ANY SALE]. 1) Convert each to the same unit price (e.g. per ounce or per count) and rank cheapest to most expensive. 2) Flag any case where the larger size costs more per unit. 3) Tell me which is the best value and whether a sale is actually cheaper per unit than the store brand.

2. Follow these steps

Snap photos of shelf tags or copy prices and sizes from a store's app.
Paste them into a chatbot and ask for price per common unit (per ounce, per 100 count).
Check the store's unit price label too, since some stores use different units for similar items.
Keep a short list of your usual items' best unit prices to spot real deals.

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What to expect, and what to do if they say no

What to expect

Store brands often win on unit price, but not always.

If they say no

Check another store's app for the same items.
Look for store loyalty or digital coupons on your usual items.

What happened when people tried it

We haven't verified a real-world example for this one yet, so it's a tool guide plus a prompt. Tried it? Tell us what happened (link below).

Why this works

The problem: Package sizes shrink and 'bulk' or 'family size' isn't always cheaper per unit.

How AI helps: AI can convert prices to a common unit, rank options and spot when the bigger pack costs more per unit.

Tools & what they cost

Tool	Cost
ChatGPT	Free option available (Paid upgrades exist, but the free version works for this) Free tier; paid plans available
Claude	Free option available (Paid upgrades exist, but the free version works for this) Free tier; paid plans available
NIST: Uniform unit pricing	Free (No cost at all) Free

What do these labels mean?

Free No cost at all.
Free option available Paid upgrades exist, but the free version works for this.
Costs money You pay a set price or subscription.
Takes a cut of savings Charges a percentage of what it saves you.
Time · Difficulty Our estimates for a typical first try, not guarantees.
Reported What the linked source says happened, often self-reported. Your results will vary.

Watch out for

No verified AI-specific success story yet. This is a how-to guide built on official sources.
Check that sizes are typed correctly; one wrong number skews the comparison.
Only buy bulk you'll use before it expires.

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Tried it? Tell us what happened, good or bad. We read every reply and may share success stories (only with your OK).

Tell us what happened

Sources

Last verified 2026-10-19. Not financial, legal, tax or medical advice. Disclaimer.