Price circuit breaker: how floors, ceilings and swing limits stop a bad price going live

What is a price circuit breaker?

A price circuit breaker is a set of checks that sits between a newly calculated price and your live eBay listing. If the new price passes every check, it goes out. If it fails one, it is blocked or held for review, and the listing keeps its last good price. The name comes from electrical circuit breakers, which cut the power when something unusual happens rather than letting the damage spread.

For any seller who reprices automatically, a breaker is essential. Repricing software can change thousands of prices a day. Without checks, one bad input, such as a misread price or a wrong currency, can put a loss-making price on a live listing within minutes, and buyers find underpriced items quickly. The breaker is what lets you trust automation with thousands of listings without watching every change yourself.

What are the parts of a price circuit breaker?

The first three work on the price itself. The last two work on the reading behind it. Both matter: a correct price from a wrong reading is not correct at all.

How do you set the floor?

The floor is the most important check. It stops any automatic change taking a listing below the price where a sale still makes the minimum you will accept.

1. Calculate break-even. Full cost plus fixed costs per order, divided by one minus all percentage fees.
2. Add your minimum profit. A fixed amount in money, so cheap items still earn something worth having.
3. Recalculate with every new cost. The floor moves when the cost moves; a floor set once and left alone soon becomes wrong.

When a new cost pushes the floor above the price the item sells for on eBay, the listing is no longer viable at today's cost. That is a decision for you, not an automatic change: raise the price and accept fewer sales, or set the quantity to zero until the cost falls. The break-even price guide walks through the calculation.

How do you set the ceiling and the swing limit?

The ceiling

The ceiling catches the opposite problem: a price so high it could only come from an error, such as a placeholder price on an out-of-stock offer or a multipack read as a single item. Overpricing loses sales rather than money, but it can also make your listing look absurd. Set the ceiling as a multiple of the listing's normal price, or as a fixed maximum for each category.

The swing limit

The swing limit compares the new price with the current one. Any change bigger than the limit, up or down, is held for review. It is the check that catches errors inside the floor and ceiling: a price that drops by half is still above your floor if the floor is low enough, but it is very unlikely to be right.

• Start from your own data. Look at how much your products normally move between readings.
• Set the limit above normal moves. Otherwise the queue fills with ordinary changes.
• Use wider limits for volatile products. Products with many sellers and frequent deals need more room.
• Tighten during sale events if needed. Events produce unusual pages and short-lived prices.

A hypothetical example

Example: suppose a listing sells at £24.99, with a floor of £19.80 and a swing limit of 25%. A new reading would set the price at £11.50, because the reader picked up a unit price. The floor blocks it on its own. A second reading would set £17.90 after a deal starts: below the floor, so also blocked, and the listing stays at £24.99 or you decide to pause it. A third would set £33.10 after a cheap seller runs out: a 32% rise, above the swing limit, so it is held for review. You check the page, see the new seller, confirm the cost and approve the rise.

How should you run the review queue?

A breaker that holds changes creates a queue, and the queue is only useful if someone clears it. A queue that grows unchecked means listings sitting on stale prices, which is its own risk.

• Review daily. Make clearing the queue part of your routine, like checking messages.
• Look at the reason. Each hold should say which check stopped it and what the reading was.
• Approve, reject or fix. Approve real changes, reject bad readings, and fix the cause if the same error keeps appearing.
• Tune the limits. If most holds are approved without change, your swing limit is too tight. If bad prices slip through, it is too loose.
• Watch for patterns. Many holds on one product often mean a variation or multipack problem with that product's page.

Breakers on variation listings

A multi-variation listing, one listing with several sizes or colours, has a price for each option, and each option usually has its own cost. Apply the breaker to each option separately. A swing limit measured on the listing as a whole can miss one option whose price has gone badly wrong while the others are fine. Each option also needs its own floor, because a cheap option and an expensive one have very different break-even prices.

When to override the breaker

Sometimes a large change is real and you want it to go out without waiting: a product whose cost has genuinely doubled, or a planned price drop for a clearance. Approve those changes from the queue rather than loosening the limits for everything. If you find yourself approving the same kind of hold every day, change the setting for that product with a per-listing override, and note why. Loosening a global limit to make one product's holds go away weakens the protection on every other listing.

What does a circuit breaker not do?

A breaker limits damage; it does not create accurate data. Keep its limits in mind.

• A wrong reading that happens to fall inside the limits passes. Accurate readings are still the first line of defence.
• It does not know about market prices on eBay unless you tell it, so it cannot tell you a price is uncompetitive.
• It does not replace your judgement on whether a product is still worth selling.
• It does not change eBay's rules. eBay allows dropshipping from a wholesale supplier, but listing an item and then buying it from another retailer or marketplace that ships directly to your buyer is not allowed under eBay's drop shipping policy, and you stay responsible for delivery and your buyer's satisfaction.

How do repricers implement circuit breakers?

Most repricing tools offer some form of minimum and maximum price. The better ones add a swing limit, checks on the reading itself and a record of every hold. Dropizon's guards check every push with a currency guard and a price circuit breaker (floor, ceiling and an optional swing limit), and holds wait for one-click review, with a reason recorded for every push and every hold. The documentation describes each guard in detail.

Whichever tool you use, test the breaker on purpose. Pick a listing, imagine a bad reading, and check what would happen. If you cannot say with confidence that the bad price would be stopped, the breaker is not set up well enough yet.

A circuit breaker checklist

• Set a floor on every listing at break-even plus your minimum profit.
• Recalculate the floor from every new cost reading.
• Set a ceiling as a multiple of the normal price or a fixed maximum.
• Set a swing limit from how much your products normally move.
• Check currency, condition and stock on every reading.
• Clear the review queue every day and tune limits from what you see.
• Test the breaker with an imagined bad reading, and again after any change to your settings.