TwoTags: Unit Price Calculator

The bigger pack is not always the better deal, and working it out in the aisle is a pain. TwoTags is a unit price calculator that does the sum for you. Point your camera at one shelf tag, then the other, and it shows which pack is cheaper, by price per 100g, per litre, per ounce or per item, and by how much. It also works as a plain price per unit calculator whenever pack sizes differ.

READ IT OR TYPE IT
TwoTags reads the price and the size off the tag on your phone, then shows you what it read so you can check it against the tag. Camera reads can be wrong, so nothing is compared until you have seen the numbers. If the tag is torn or the light is bad, you can enter the price and size yourself.

SIZES THAT DO NOT MATCH
500g against 1.2kg. 6 x 330ml against a 2 litre bottle. A 16 ounce box against 500g. A 12 roll pack against a 9 roll pack. TwoTags converts them to one unit and lets you compare unit prices, in metric or US measures. It tells you when two packs cannot fairly be compared, such as one sold by weight and one by volume.

WHEN A TAG HAS TWO PRICES
If the reader finds a member price and a shelf price, both show up after the read, so you pick the one you will really pay.

THE PACK THAT GOT SMALLER
Tap Bought this pack and TwoTags keeps the item, shop, price, size and date in your Book. With the one-time unlock, the next time you compare that item you get one plain line if your recorded size or price changed: on 5 March your reading was 500g, per unit it now costs 11.1% more. It only ever shows your own two readings, side by side.

YOUR PRICE BOOK
Search any item you have kept and see every reading by date and shop, your own grocery price comparison over time. The unlock adds a line chart of its unit price, so you can see when your usual cereal crept up and which shop was cheaper last time.

WHAT YOU SAVED
Each time you take the cheaper pack, TwoTags adds the estimated difference to Saved this month. It is worked out from your own readings, not a receipt.

SHARE THE FIND
Make a small card with both packs, the winner and the difference, and send it to whoever does the other half of the shopping.

STANDARD AND UNLOCKED
Comparing two packs, Bought this pack, the Book, sharing and backup are all in the standard version, with one small banner in the Book and none on the compare screen. A one-time unlock adds the price history chart, shrink and price rise lines, up to six packs in one compare and adding readings by hand, and removes the banner. There is no subscription and no account.

WHAT STAYS ON YOUR PHONE
Tags are read on your phone and nothing you read or type is uploaded. The picture of a tag stays on your phone until you start another compare. A backup is a file you keep and can move to another phone.

TwoTags does not know live prices and cannot tell you which shop is cheapest today. It works out unit prices from what you read or type, so check the tag before relying on the answer.

Questions? Write to support@clearstackapps.com

Recent changes:
First release: read two shelf tags with your camera and see which pack is cheaper per unit, keep what you buy in a price book, and spot a pack that got smaller.