How to use this calculator
- Enter the regular price of one item.
- Enter the paid and free item counts for one complete set.
- Optionally enter the total items you will take home, including free ones. Leave it blank for one set.
- Check the effective discount, total paid, and price per item.
Example: Buy 3, get 1 free
Suppose each item normally costs $5. You pay $15 for three items and receive four items in total. Buying four at regular price would cost $20, so you save $5 and pay an effective price of $3.75 per item.
One out of the four items is free, so the promotion is equivalent to 25% off.
Effective discount formula
When you enter a total quantity, the offer applies to complete sets only; leftover items cost full price. Five $5 items under a buy-3-get-1-free offer cost $20: a 20% discount on the $25 regular total. The offer must be repeatable with no limit on free items. Mixed prices are not supported. See the complete-set, mixed-price, and needed-quantity examples.
For one complete set, use free items ÷ (paid items + free items) × 100. Buy one, get one free is 50% off. Buy two, get one free is about 33.33% off. Buy four, get one free is 20% off.
Frequently asked questions
Does “buy 3, get 1 free” mean I receive four items?
Usually, yes: you pay for three and receive one additional item free. Always check the promotion's wording and eligible items.
What if the items have different prices?
This calculator assumes every item has the same regular price. Some promotions make the lowest-priced item free, so use the actual receipt total when prices differ.
Does it automatically add items to qualify?
No. It uses the total you enter. Under a buy-3-get-1-free offer, entering three total items gives no free item; enter four to include the free fourth item.
Is a bulk promotion always worth it?
No. The effective discount only helps if you need the full quantity. Storage, expiration dates, and purchase limits may change the practical value.