Use the BOGO Deal Calculator to find the true effective discount, total savings, final deal price, and average item cost for buy-one-get-one promotions.
BOGO Deal Formula
A buy-one-get-one or buy-X-get-Y offer is easiest to compare by finding the regular total, the deal savings, and the effective discount across every item received. For same-price items, the calculator uses:
Regular Total = P * (B + G) * N Savings = P * G * (D / 100) * N Deal Total = Regular Total - Savings
The effective discount is:
Effective Discount (%) = Savings / Regular Total * 100
Variables:
- P is the regular price per item
- B is the number of items purchased at full price in each deal group
- G is the number of reward items in each deal group
- D is the discount applied to each reward item, where 100 means free
- N is the number of complete deal groups purchased
For a second-item percentage-off offer with two differently priced items, the savings equal the designated discounted item's regular price multiplied by its discount percentage. The calculator then divides the savings by the combined regular price of both items to show the true discount across the whole transaction.
Common BOGO Effective Discounts
This table assumes every item has the same regular price. When item prices differ, calculate the discount against the total regular value of the specific items in your cart.
| Offer | Savings on equal-price items | Effective discount |
|---|---|---|
| Buy 1, get 1 free | 1 of 2 items | 50.00% |
| Buy 2, get 1 free | 1 of 3 items | 33.33% |
| Buy 3, get 1 free | 1 of 4 items | 25.00% |
| Buy 1, get 1 at 50% off | Half of 1 item | 25.00% |
| Buy 2, get 1 at 50% off | Half of 1 item | 16.67% |
| Buy 1, get 1 at 25% off | One-quarter of 1 item | 12.50% |
Example Problems
Example 1: Buy one, get one free.
Two shirts normally cost $30 each. The regular total is $30 * (1 + 1) = $60. One shirt is free, so the savings are $30 and the deal total is $30. The effective discount is $30 / $60 * 100 = 50%.
Example 2: Buy one item and get a lower-priced item 50% off.
The full-price item costs $40 and the discounted item normally costs $30. The regular total is $70. The savings are $30 * 50% = $15, so the deal total is $55. The effective discount is $15 / $70 * 100 = 21.43%, not 50%, because only one portion of the purchase receives the advertised discount.
Frequently Asked Questions
Is buy one, get one 50% off the same as 25% off?
It is equivalent to 25% off the combined regular price only when the two items have the same price. If the second item costs less, the effective discount is below 25%. Many stores also apply the discount to the lower-priced eligible item.
How do I compare a BOGO deal with a straight percentage discount?
Use the effective discount, not the headline wording. Calculate the BOGO savings as a percentage of the regular total for every item, then compare that percentage with the storewide discount. Also account for whether you actually need the extra item.
Does a free item always mean I saved its full price?
Only when you would have purchased both items at regular price. If the promotion causes an unnecessary purchase, the cash outlay may be higher than your normal spending. The calculator measures transaction savings, while your personal savings depend on planned use.
