Lightning Deals are expensive. Here is the real number.

A Lightning Deal costs you the discount on every unit you sell during the deal window, plus a flat fee that Amazon charges for running the promotion. The fee varies by category and season. In competitive categories during Q4, the fee can exceed $700.

The deal runs for six hours, or until the inventory you allocated sells out. You choose how many units to allocate. The discount you set must be at least 15 percent off the recent average price, and Amazon must approve the deal before it runs.

What it costs in practice

Say you allocate 100 units of a $30 product and set a 20 percent discount. You give up $6 per unit, or $600 total in discount. Add a $400 Lightning Deal fee. The total cost of running the deal is roughly $1,000.

If the deal helps you sell 100 units in six hours that would have taken a week to sell normally, you accelerated revenue by about six days for $1,000. Whether that is worth it depends on what you do with the ranking momentum.

Where the upside is

The main reason sellers run Lightning Deals is the rank boost. A high-velocity six-hour window can push the product up in the search results, and that boost sometimes lasts for days or weeks after the deal ends. If the product converts well at the organic price, the deal pays for itself through sustained higher placement.

Where it does not pay

Low-margin products rarely benefit. If the net margin is 20 percent on a $25 product, you make $5 per unit. Discount 20 percent and pay a $300 deal fee on 100 units, and you lose money on every unit you sell during the deal window, even before counting the fee. The post-deal rank would need to more than double your organic sales for the math to work, and that does not happen as often as sellers hope.

Run the numbers before you submit the deal. If the deal fee plus discount exceeds what you would spend on PPC to get the same sales, skip the deal and run ads instead. The control is better and the cost is lower.