BOGO Discount Calculator

Contribution per deal against a single sale.

Contribution per deal against a single sale. Buy one get one free is a 50% discount stated differently, and three for two is 33%.

Written and maintained by Mohit PatelLast checked August 4, 2026How we build these

Currency

Price

Contribution margin

Offer

Share of buyers who take it

Share who would have bought two anyway

Contribution per deal

−$6.96

50% effective discount

Units given2

Units paid for1.0

Contribution per deal−$6.96

Against a single full-price sale$25.52

The deal produces less contribution than one full-price sale, so it only works if it brings in customers who would not have bought at all. On existing customers it is a straight margin giveaway.

How the BOGO Discount Calculator works

Buy one get one free is a 50% discount stated differently, and three for two is 33%. The right comparison is contribution per deal against contribution from a single full-price sale, if the deal wins, it works whenever it genuinely moves an extra unit.

Also known as: buy one get one free value · BOGO effective discount · 2 for 1 discount percentage

What buy one get one actually discounts

Buy one get one free is a 50% discount expressed differently, and it is perceived as considerably more generous. The customer receives two items for the price of one, and the effective discount per unit is exactly half.

Buy one get one half price is a 25% discount across the pair. Buy two get one free is 33%. Each sounds larger than the equivalent percentage off, which is most of the reason the format persists.

The margin arithmetic follows the same rule as any discount: the profit effect is the effective discount divided by the contribution margin. A BOGO on a 50% contribution margin removes the entire contribution across the pair, which means it is only worthwhile for reasons other than the immediate profit.

The cost of goods is what decides it

BOGO gives away a physical unit, so it costs the landed cost of that unit rather than a percentage of the price. That makes it cheap for high-margin goods and prohibitive for low-margin ones.

A £30 item costing £5 to make gives away £5 of cost against £30 of retained revenue on the pair, which is a contribution of £20 across two units. Perfectly viable.

The same offer on a £30 item costing £20 gives away £20 to retain £30, producing a contribution of minus £10. That is a transaction that costs money to complete, and BOGO offers on thin-margin goods are frequently exactly this without anyone having run the arithmetic.

When it beats a straight discount

BOGO moves units, which is the point when the objective is clearing stock. Two units leave the warehouse instead of one, at a cost of one unit's landed cost rather than half the retail value.

It also increases the customer's holding of the product, which for consumables means they buy from you again later rather than switching. Detergent, coffee and consumables generally benefit from this in a way that durable goods do not.

Where it works badly is on items with a long replacement cycle. Giving someone two of something they will not need again for three years simply removes a future sale, and the promotion has bought forward revenue rather than created it.

The mixed-item versions

BOGO across different products, where the free item differs from the purchased one, gives control over what is given away. The free item can be a slow-moving line, a lower-cost item, or something that introduces a customer to another part of the range.

The usual structure is that the cheaper item is free, which caps the cost. Stating that clearly matters: customers who assume the more expensive item will be free are annoyed at checkout, and that annoyance costs conversion.

Cross-category BOGO is a genuine merchandising tool rather than a discount. Free accessory with a main product, free sample with a full-size item, free consumable with a device. Each has a low cost of goods and a real perceived value, which is the shape that makes a promotion efficient.

The rules on how it is described

Free means free, and regulators take that literally. If the price of the first item rises to fund the second, the offer is not what it says, and both UK and EU rules treat that as misleading.

The reference price rule applies here too. A BOGO where the single-unit price was increased before the offer began is exactly the practice the Omnibus Directive was written to address.

The practical protection is documentation: keep the pricing history that shows the single-unit price was unchanged. Sellers who run BOGO frequently and never adjust the base price have nothing to worry about and should be able to demonstrate it if asked.

Where to go next

The BOGO Discount question rarely arrives on its own. These are the ones that usually come with it:

Buy X Get Y Calculator — Set the threshold above the normal basket.
Bundle Discount Calculator — Only worth it if the attachment is real.
Percentage Off Calculator — And the volume it needs to break even.
Etsy Fee Calculator — Every Etsy fee on one sale, itemised.

Not financial advice. Marketplace fees change, and they vary by country, plan and seller status. Every rate here is an editable default, not a quoted price, check the platform's current fee schedule before you price a product against it. This is not tax or business advice.

Frequently asked questions

What discount is BOGOF equivalent to?

Fifty percent, since two units go out for the price of one. Buy one get one half price is 25%, and three for two is 33%.

Why do BOGO offers work at all?

Because they move two units of contribution instead of one, provided the second unit is genuinely incremental. If the customer would have bought both anyway, you have simply halved the price.

Which products suit them?

Consumables and anything people stock up on. Products bought one at a time and used slowly are poor candidates, the second unit displaces a future full-price sale.

Are they better than a straight discount?

Usually, at the same effective percentage, because they move more units and read as better value. They also clear stock faster, which matters when that is the reason for the promotion.