How to Calculate BOGO and Buy X Get Y Savings
BOGO promotions are easiest to compare when you translate the offer into the number of items paid for and an effective price per item.
Count complete promotion groups
Add the number bought and the number free to get the group size. Divide the quantity needed into complete groups, then price any leftover items according to the offer terms.
- Group size = items bought + free items
- Paid items per complete group = items bought
- Savings = regular total − promotional total
BOGO example
Buy one, get one free has a group size of two. If each item is $24 and you need four, you pay for two: $48 instead of $96. The effective price is $12 per item.
BOGO quantities compared
Incomplete groups matter: the advertised percentage applies only to complete promotional groups.
| Scenario | Regular total | Promotional total | Result |
|---|---|---|---|
| Buy 1 get 1; two × $20 | $40.00 | $20.00 | Save $20; $10 per item |
| Buy 2 get 1; three × $15 | $45.00 | $30.00 | Save $15; $10 per item |
| Buy 2 get 1; four × $15 | $60.00 | $45.00 | Fourth item is full price |
Handle mixed prices conservatively
Many Buy X Get Y promotions make the lowest-priced eligible product free. If a $30 item and a $10 item form a buy-one-get-one pair, the saving may be $10—not half of the $40 combined price. The effective discount is therefore 25%.
For several mixed-price items, groupings can depend on the retailer’s rules. The safest approach is to inspect which cart line receives the discount and compare the final promotional total with the same quantity at regular prices.
Match the deal quantity to actual demand
A promotion’s effective unit price applies only to the quantity purchased. Buying six perishables because two are free can cost more than buying the two you need at regular price. Compare the total for your real demand period, not merely the price per item.
- Count complete deal groups and full-price leftovers.
- Check customer, order, and product quantity limits.
- Use the price of the item actually discounted.
- Estimate waste for food, cosmetics, and expiring goods.
- Compare with a store-brand or smaller-pack alternative.
Buy two, get one example
At $15 per item, three items cost $30 instead of $45. If you need four, the fourth item normally costs another $15, making the total $45.
Compare only quantities you need
A high percentage saving can still waste money if the promotion makes you buy perishables or duplicates you will not use. Compare the cost for the quantity you actually need.
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