The festive sales are here and every second banner says “buy one, get one free”. It sounds like half price, and sometimes it is. But whether you actually save money depends on one simple question that most shoppers skip: will you really use the second item?
What buy one get one free actually means
“Buy one, get one free”, often shortened to BOGO or BOGOF, is a sales promotion in which a second unit is given free only if the first unit is bought at full price. It is also sold as “two for the price of one”. The idea is old: the concept is credited to the 18th century retail entrepreneur Josiah Wedgwood.
The key detail is in the wording. You never get a discount on the first item. You pay full price for it, and the deal only becomes a discount if you count the second item as something you needed.
The formula to find the real discount
To compare any “buy X, get Y free” offer with a normal percentage discount, divide the free items by the total items you take home:
Effective discount (%) = free units ÷ total units received × 100
- Buy 1, get 1 free: 1 ÷ 2 = 50% off per item
- Buy 2, get 1 free: 1 ÷ 3 = about 33.3% off per item
- Buy 3, get 1 free: 1 ÷ 4 = 25% off per item
Watch out for the cousin of this deal, “buy one, get one 50% off”. You pay 1.5 times the price for two items, which is 75% of the price per item, so the real discount is only 25%, not 50%.
A real example: one T-shirt or two?
Say a T-shirt costs ₹799 and the shop runs a BOGO offer. You pay ₹799 and walk out with two shirts, so each one costs ₹399.50. That is a genuine 50% saving per shirt, as long as you wanted two.
Now imagine the shop next door sells the same kind of shirt at 40% off, with no need to buy two. One shirt there costs ₹799 × 0.6 = ₹479.40.
- If you need two shirts, BOGO wins: ₹799 for two against ₹958.80 for two at 40% off.
- If you need only one shirt, the 40% off deal wins: ₹479.40 against ₹799, so the “free” shirt costs you ₹319.60 extra.
The same logic applies to a “buy 2, get 1 free” offer. Three shirts for ₹1,598 works out to about ₹532.67 each, a 33.3% discount, but only if all three get worn.
Why the second item feels worth more than it is
The economist Alex Tabarrok has argued that these promotions work because shoppers value the first unit much more than the second. Faced with a seemingly equivalent “half price” offer, many people would buy just one item, because the second one is worth less to them than even the discounted price. A BOGO deal removes that choice: to get the discount, you have to take both.
That is why the most useful number is not the price per item on the shelf, but the price per item you will actually use:
Effective price per unit = total paid ÷ units you will really use
Common mistakes with BOGO deals
Buying perishable food you cannot finish
Two for one offers in the food industry have been criticised for contributing to food waste, because many of these foods have a short shelf life and shoppers end up passing the use by date. Take a loaf of bread at ₹50 on BOGO. If you finish only one loaf before it goes stale, you paid ₹50 per loaf eaten, exactly the normal price. If you manage one and a half loaves, the real cost drops to about ₹33.33 per loaf, still well short of the advertised half price.
Letting the deal decide how much you buy
Another criticism is that BOGO offers, especially when combined with other discounts, encourage people to buy more than they otherwise would, and so to spend more money overall. A good test before you reach the counter: would you buy the second item at ₹399.50 if it were sold on its own? If the answer is no, the honest discount on your purchase is zero.
The quick checklist before you grab the deal
- Count how many units you will genuinely use, not how many the offer gives you.
- Divide the total price by that number to get your real price per item.
- Compare that figure with any straight discount on a single item nearby.
- For food, check the use by date and ask whether you will finish both before it.
