A person reads every message

No. The largest pack usually has the lowest price per unit, and that is arithmetic rather than advice — it holds only if you get through it.

A lower unit price on something you throw half away is not cheaper, it is more expensive with extra steps. Unitwise puts that sentence next to every result at the same weight as the result itself, because a tool that only ever reports the lowest unit price would systematically push people into over-buying.

There is also the case where the unit changes the answer. A box whose tablets are heavier can be the cheapest per 100 g and the dearest per tablet at the same time. Which of those two numbers matters is a question about how you use the thing, and only you can answer it.

Unitwise does not answer that, and it will not try. Ask it anything about use-by dates, shelf life, spoilage or whether something is safe and it stops rather than converting anything: whether something is still good to eat is a question for the label and your own judgement, not a price calculator.

The same goes for nutrition. There are no calorie figures, no ingredient analysis and no health content anywhere in this service.

Shop names, store numbers and loyalty-scheme wording are redacted before a photograph is stored, and the redaction happens on the way in rather than at display time.

Photographs that appear to contain a person are refused at upload and are not stored at all.

Your photographs and the text read from them are not used to train any model, ours or anyone else's. Uploaded label photographs are held for 30 days unless you delete them sooner, and you can delete them at any time from the comparison screen.

The model does one job: reading the price, the net quantity, the unit and any promotional wording off a photograph. It does not do the sums and it does not decide which size is cheapest.

Every conversion is calculated in your browser and printed with its arithmetic, so a result reads 5.10 ÷ 1200 × 100 = 0.425 per 100 g rather than just an answer. If the model has misread a figure you will see it in the working before you act on it, and you can correct any value by hand.

Reading a photograph is still a best effort. Check the figures against the label in front of you — that is what the working is there for.

No, and it is built so that it cannot. Shelf labels use different units for all sorts of ordinary reasons. Unitwise only places them on one scale; it makes no judgement about whether any label complies with unit-pricing rules, and it never comments on a retailer.

Because store identifiers are redacted on the way in, a result cannot be tied back to a shop in the first place. Using output from this service in a complaint or a public accusation against a retailer is prohibited by the terms.

Aisle is $5 a month or $48 a year, Trolley is $15 a month or $144 a year, and all prices include VAT at 20%. Subscriptions renew automatically until you cancel, and you are shown the amount, the period, the next charge date and how to cancel on a screen of its own before you pay.

Cancelling takes two clicks from your billing page — never a phone call and never an email. You keep access to the end of the period you have paid for. Charges appear on your statement as UNITWISE.

You have 14 days to cancel a new subscription and another 14 days after each renewal. Where you asked us to start straight away and acknowledged that this ends the 14-day right, that acknowledgement is recorded and repeated in your confirmation email. The full detail, including the statutory cancellation form, is on the cancellation page.

Credits are a service usage allowance and nothing else: not money, not stored value, not redeemable for cash and not transferable. A question costs one, reading one shelf label costs one, and a comparison card costs three.

Your allowance resets each billing period and does not carry over. There are no top-up packs and no stored balance — if you run out, you can move up a plan or wait for the reset.

You need to be 13 or older to hold an account, and anyone between 13 and 17 needs a parent or guardian's consent. Billing requires an adult.