Shopping & Supermarket Deals
Unit price comparison across grams, ml, and packs to reveal which supermarket deal is truly cheaper.
Shopping calculators check what you really pay: which pack is cheaper per gram or per item, and how much sales tax is added at the till in the US and Canada. They work from the shelf price you can see and give an answer in a few seconds on your phone.
The Unit Price Comparison Calculator puts two products side by side and works out the price per 100g, per 100ml or per item, then names the better buy and how much cheaper it is. It accepts grams, kilograms, millilitres, litres and item counts. Bigger is not always cheaper: 500ml at 90p is 18p per 100ml, while 2 litres at £4 is 20p per 100ml, so the small bottle wins. A 6-pack at £3.30 works out at 55p an item against 70p for a single. The saving is based on unit price, not pack price.
US shelf prices leave out sales tax, which each state sets and cities and counties often add to. The US Sales Tax Calculator by State adds the 2026 state rate plus an editable local rate, or takes the tax out of a receipt total. New Jersey charges 6.625% with no local sales tax, so $100 becomes $106.63. Alaska, Delaware, Montana, New Hampshire and Oregon have no statewide sales tax, although Alaska lets cities and boroughs charge their own.
The Canada Sales Tax Calculator (GST, HST, PST, QST) covers every province and territory with the 2026 rates. Alberta and the three territories charge 5% GST only, Ontario 13% HST, Nova Scotia 14% and New Brunswick, Newfoundland and Labrador and Prince Edward Island 15%. British Columbia, Manitoba, Saskatchewan and Quebec charge a separate provincial tax alongside GST; in Quebec the combined rate is 14.975%. Both tax calculators also work in reverse, which helps with expense claims and refunds.
UK and US shoppers use the unit price tool at the shelf, and North American shoppers use the tax tools before checkout. Everything runs in your browser and updates as you type.
-
Unit Price Comparison Calculator
Compare two products by unit price to see which is better value. Enter each price and pack size in g, kg, ml, litres or items.
-
Canada Sales Tax Calculator (GST, HST, PST, QST)
Add GST, HST, PST or QST to a price, or take the tax out of a total, for any Canadian province or territory, with the 2026 rates.
-
US Sales Tax Calculator by State
Add sales tax to a price or take it out of a total for any US state, with the 2026 state rate, an editable local rate and a price-before-tax reverse mode.
Common questions about shopping & supermarket deals
How do I compare prices of different pack sizes?
Convert both to the same unit and compare the price per unit. 400g for £3.20 is 80p per 100g and 1kg for £6.80 is 68p per 100g, so the larger bag is 15% cheaper per 100g. The Unit Price Comparison Calculator does this for grams, millilitres, litres or items.
Are multipacks always better value?
No, so compare the price per item. A 6-pack at £3.30 is 55p each, cheaper than a single at 70p, but an offer on singles can reverse that. You cannot compare items with grams or millilitres, so choose items as the unit for both products in the Unit Price Comparison Calculator.
How do I calculate HST in Ontario?
Multiply the price before tax by 13%. On a $100 item the HST is $13, so you pay $113, or multiply by 1.13 to get the total in one step. HST replaces both GST and PST in Ontario, so there is no separate provincial sales tax to add.
How do I remove sales tax from a total?
Divide the total by 1 plus the combined rate. A $106.63 receipt in New Jersey divided by 1.06625 is $100 before tax. In Ontario, $50 divided by 1.13 is $44.25 plus $5.75 of HST. Both sales tax calculators have a reverse mode that does this for you.
Which US states have no sales tax?
Alaska, Delaware, Montana, New Hampshire and Oregon have no statewide sales tax, so $100 stays $100 in Oregon. Alaska is the exception in practice, because it lets cities and boroughs charge local sales tax, averaging about 1.82%. The US Sales Tax Calculator by State covers all 50 states.