Bid increments are the least discussed setting in any auction platform and one of the most consequential. Set them too large and you exclude bidders who would have gone a little higher. Set them too small and lots take forever to close while bidders lose interest. Both cost money, and neither shows up in any report.
Here is how to think about them properly.
What an increment actually is
The minimum amount by which a new bid must exceed the current high bid. In any serious platform this is not a single number but a table that scales with price:
- $0 – $100: increment $5
- $100 – $500: increment $10
- $500 – $1,000: increment $25
- $1,000 – $5,000: increment $50
- $5,000 – $25,000: increment $250
- $25,000+: increment $1,000
That is an illustrative shape rather than a prescription — the right table depends entirely on your category. But the principle holds everywhere: the increment should be roughly 2-5% of the current price. Below that, bidding drags. Above it, you start excluding people.
How increments interact with proxy bidding
This is where most confusion arises. With proxy bidding, a bidder sets a maximum and the system bids on their behalf in increments as needed. See proxy bidding for the mechanics.
The consequence: the winning price is usually the underbidder’s maximum plus one increment, not the winner’s maximum. So the increment size directly determines the gap between what the market was willing to pay and what you actually collected.
With a $50 increment on a lot where the underbidder maxed at $1,220, the winner pays $1,270. With a $25 increment, they pay $1,245. Across a catalogue of four hundred lots, that difference is not trivial — and it runs in both directions depending on where the maximums fall.
What goes wrong at each end
Increments too large
- Bidders at their limit cannot make one more small step, so they stop
- Low-value lots become unbiddable — a $10 increment on a $15 item is absurd
- The jump feels arbitrary and bidders disengage
Increments too small
- Lots take a very long time to reach real money, and in a live sale that destroys pace
- Bidding wars become tedious rather than exciting
- Proxy bidding generates enormous numbers of automated micro-bids, which is a load problem as well as a UX one
Practical guidance by category
- General estate and household — start small ($1-$5) because much of the catalogue is low value, and scale steeply.
- Vehicles — $100-$250 in the retail range, larger above. Small increments on a $20,000 car waste everyone’s time.
- Heavy equipment — $250-$1,000 depending on price band. Bidders here think in thousands.
- Fine art and antiques — traditional saleroom steps, typically following a 10-20-50 progression within each decade of value.
- Collectibles and cards — finer increments than most categories, because value differences between grades are precise and bidders bid to those.
- Charity auctions — 5-10% of the starting bid. Round numbers, because guests are not calculating.
The advanced options
Two capabilities worth having in your platform:
- Per-lot overrides. Your standard table will be wrong for some lots. A high-value item in a low-value sale needs its own increments. Make this easy for the person cataloguing.
- Custom bid amounts. Allowing a bidder to enter any amount above the minimum, rather than only the next increment, captures the bidder who wants to jump. Jump bidding is a real strategy — a bidder signalling seriousness to discourage competition — and platforms that prevent it lose those bids.
Increments and soft close together
These two settings interact and should be tuned together. Very small increments plus a long soft-close extension produces auctions that run for hours as bidders creep upward. Large increments with no soft close produces sniping.
The combination that generally works: increments at roughly 2-5% of current price, with a soft-close extension of two to five minutes on any bid in the final window. Enough to prevent sniping, short enough that lots actually finish.
Testing your table
Pull your last few sales and look at the closing prices. If a noticeable share of lots closed at exactly one increment above a round number, your increments are probably fine. If lots are stalling at prices just below where you would expect, or if the same bidders repeatedly stop at the same point, your increments are likely too coarse in that band.
It is worth an hour of analysis, once. Most auction operators set increments when they configure the platform and never revisit them.
Related: absolute vs. reserve auctions, what a buyer’s premium is, and the anatomy of a high-converting auction product page.
Frequently asked questions
What is a good bid increment percentage?
Roughly 2-5% of the current price is a reasonable working range across most categories. Tune from your own closing data rather than treating it as a rule.
Should bidders be able to bid any amount?
Generally yes, above the minimum. Jump bidding is a legitimate strategy and blocking it loses you bids from your most motivated buyers.
Can increments differ per lot?
They should be able to. A standard table plus per-lot overrides is the right structure. Talk to our team if your current platform cannot do this.
