Bidding Strategy and the Psychology of the Saleroom
What Is Bid Increment at Auction: Reading the Steps to Time Your Entry
A bid increment is the fixed step by which an auctioneer, or an online bidding platform, advances the price of a lot. Phillips advances in increments of up to 10 percent; Sotheby's uses roughly 10 percent of the previous bid. Their tactical use is a separate matter.
A bid increment is the fixed step by which an auctioneer, or an online bidding platform, advances the price of a lot. Ask what is bid increment at auction and the published answer is procedural. Phillips advances "in increments of up to 10%, subject to the auctioneer's discretion", and Sotheby's puts live bidding steps at "approximately 10% of the previous bid". Those rules describe procedure. Their tactical use is a separate matter. Increments set the tempo of a sale, and their width at any given price tells an attentive collector what a single raise costs, how many raises separate the standing bid from a personal ceiling, and whether entering now is cheaper than entering three steps later.
Key takeaways:
- Phillips publishes a fixed ladder in its UK Auction Buyer's Guide, effective 12 April 2026: £50 steps to £1,000, £500 steps from £5,000, £2,000 steps from £20,000, £10,000 steps from £100,000, and auctioneer discretion above £200,000.
- Sotheby's Guide for Buyers records salerooms moving at 50 to 120 lots per hour, leaving a bidder roughly 30 to 72 seconds of decision time per lot.
- Christopher Avery showed in The Review of Economic Studies (1998) that a jump bid, a raise above the standing increment, acts as an intimidation device pushing rivals onto less aggressive bidding functions.
- Hester Zhang, Assistant Professor of Economics at IESE Business School, found in 2024 that jump bidders "tend to pay a lower price than the seller expected to get in revenue".
What Is Bid Increment at Auction, and Why the Step Widens
The step widens because a fixed sum stops being meaningful as the price climbs. A £50 raise is 5 percent of a £1,000 bid and 0.05 percent of a £100,000 bid, which would turn the closing minutes of an important lot into an unreadable crawl. Houses therefore publish a ladder in which the increment grows with the standing bid and holds the proportional step near 10 percent. The Auction Collective describes these bands as increasing "roughly by 10% each time", with the pattern repeating as zeros are added. Phillips sets out the ladder governing its London sales in the UK Auction Buyer's Guide.
| Standing bid | Published increment | One step as a share of the bid |
|---|---|---|
| £1,000 to £2,000 | £100 | 5.0 to 10.0 percent |
| £5,000 to £10,000 | £500 | 5.0 to 10.0 percent |
| £20,000 to £30,000 | £2,000 | 6.7 to 10.0 percent |
| £100,000 to £200,000 | £10,000 | 5.0 to 10.0 percent |
Bands are quoted from Phillips; percentages are calculated from those bands. The pattern that matters is the sawtooth inside every tier: a raise is at its most expensive, proportionally, at the bottom of a band and cheapest at the top. Moving from £20,000 to £22,000 costs 10 percent, while the same £2,000 taken from £28,000 costs 7.1 percent. Phillips adds that "the auctioneer may vary the increments during the course of the auction at his or her own discretion", so the ladder is a planning floor rather than a guarantee.
What is bid increment at auction on a timed online platform?
On a timed online sale no auctioneer is present to widen a step or accept an odd number, and the increment becomes an absolute rule. Sotheby's confirms its platform "uses pre-determined bidding increments" and "will then place incremental bids on your behalf up to your maximum bid for as long as you are the highest bidder". This is proxy bidding: a ceiling is disclosed to the machine, and the machine spends the minimum required to hold the lead. Arts Economics reported for Art Basel and UBS in March 2026 that online-only sales accounted for 15 percent of the global art market, or USD 9.2 billion, so these rules now govern a substantial share of transactions. Two mechanics govern the endgame. Ties resolve by timestamp, since Sotheby's executes the first of two identical maximum bids. And a bid placed within one minute of the scheduled close extends that lot by two minutes from the last bid, for up to two hours, which removes sniping as a strategy and returns the contest to the ceiling each party set before the sale opened.
What a Jump Bid Signals to the Room
A jump bid exceeds the published increment, and it is the only way a bidder can speak during a sale. Christopher Avery formalised the mechanism in "Strategic Jump Bidding in English Auctions", published in The Review of Economic Studies in April 1998. Jump bids, he concluded, serve as correlating devices which select asymmetric bidding functions to be played subsequently. The jump assigns roles: one bidder becomes the aggressor, the others accept a passive line and drop out earlier than their private valuations justify.
Hester Zhang, Assistant Professor of Economics at IESE Business School, tested what that costs the seller. Her work, published by IESE Insight on 29 February 2024, describes the jump as a message that the informed bidder "is, therefore, willing to take the risk of upping their offer", and reports that jump bidders "tend to pay a lower price than the seller expected to get in revenue". Where transaction costs are high, Zhang notes, a jump can instead raise participation and seller revenue.
Three jumps carry three meanings. Early, before the reserve is cleared, a jump usually signals impatience. Landing exactly on the low estimate, it is often an absentee or priority bid being executed, which under Phillips's rules must sit at or above the published low estimate and be lodged at least 48 hours ahead. Late, above the high estimate, from a bidder who has been silent, it claims a private valuation the room cannot see, and the correct response is to check your own ceiling.
Timing Your Entry by the Rhythm of the Steps
Sotheby's records auctions running at 50 to 120 lots per hour, giving a bidder 30 to 72 seconds per lot. Deciding inside that window requires the arithmetic done beforehand, which is what separates setting your ceiling and deciding what a work is worth to you from improvising under pressure. Read this way, what is bid increment at auction becomes a question of counting rather than of definition.
- Convert the ceiling into steps. Subtract the standing bid from your maximum hammer and divide by the current increment. A £30,000 ceiling against £22,000 in a £2,000 band leaves exactly four raises, a number you can hold during a sale.
- Locate the band boundaries in between. The Phillips step changes at £30,000, £50,000 and £100,000. A ceiling sitting just above a boundary is worth less than it looks, because the final raise beneath it is larger.
- Net the ceiling of fees first. At LLB Auction the buyer's premium is 20 percent, disclosed upfront. A £30,000 all-in budget is a £25,000 hammer ceiling, between two and three increments below the unnetted figure.
- Watch where the reserve sits. Phillips sets the reserve at a percentage of the low estimate, never above it, and opens no-reserve lots near 50 percent of that estimate. Bidding below the low estimate is often the auctioneer working toward the reserve.
- Count your opponent's steps rather than their money. A rival answering instantly for six consecutive raises who then hesitates for two has reached the region of their limit. Hesitation at a band boundary is a reliable indication that a rival is approaching their limit.
Skipping a Round to Break the Momentum
Two bidders alternating at a steady tempo produce a ladder that climbs on its own. Twelve consecutive £2,000 steps carry a lot from £20,000 to £44,000 without either party making a decision larger than 10 percent. Skipping a round interrupts the pattern, because the pause forces the auctioneer to look for a bid rather than take one.
The arithmetic is worth doing in advance. A lot standing at £22,000 with a £30,000 ceiling gives four raises: £24,000, £26,000, £28,000 and £30,000. Answering every round spends all four inside a minute and reaches the ceiling with nothing in hand. Letting the rival take £24,000 unanswered and re-entering at £26,000 uses one raise and keeps two, and it lands on a bidder who has just paid 9.1 percent to advance a lot that no one else wanted at £22,000. That is the mechanism behind the psychology that makes smart collectors overpay: each step looks small in isolation, and answering every one of them is what carries a hammer price past its estimate.
The skip has a limit on timed online sales, where the proxy engine answers in whole increments and never hesitates. Against a proxy engine a skipped round produces no reaction, so the ceiling set before the sale opens carries the decision.
FAQ: What Is Bid Increment at Auction
What is bid increment at auction, stated in one sentence?
A bid increment is the minimum amount by which the price of a lot must rise for a new bid to count, published in advance by the house as a ladder tied to the standing bid. Phillips advances "in increments of up to 10%, subject to the auctioneer's discretion", and Sotheby's uses steps of approximately 10 percent of the previous bid, so a £5,000 lot typically moves in £500 stages.
Can I bid an amount that is not a whole increment?
In a live saleroom, sometimes. Phillips states that "the auctioneer may vary the increments during the course of the auction at his or her own discretion", so an odd figure may be taken from the floor. Online, no. Sotheby's applies pre-determined increments to platform bids, and Phillips warns that absentee bids failing to conform to the published ladder "may be lowered to the next bidding increment".
Does a jump bid actually work?
The evidence says it works for the bidder and costs the seller. Christopher Avery showed in The Review of Economic Studies (1998) that jump bids act as intimidation devices, pushing rivals onto less aggressive strategies. Hester Zhang of IESE Business School reported in 2024 that jump bidders "tend to pay a lower price than the seller expected to get in revenue". The effect weakens where transaction costs are high, since jumps can then draw more participants in.
How do increments work when a timed online lot is closing?
Increments stay fixed and the closing time moves. Sotheby's extends any lot receiving a bid within one minute of its scheduled end by two minutes from that bid, for a maximum of two hours. The extension neutralises last-second sniping and returns the outcome to the maximum each bidder set. The proxy engine then advances in whole increments only, spending the least needed to hold the lead.
How LLB Auction Serves a Collector Reading the Increments
LLB Auction runs timed online sales of 7 to 14 days on its own platform, with the ladder and every cost visible before the first bid.
Intake discipline. Roughly 40 percent of submissions are rejected. Anything reaching a published ladder cleared that threshold first, with per-lot certificate verification, ownership history and conservation records reviewed before cataloguing.
Cost transparency. The buyer's premium is 20 percent and the seller's commission 10 percent, disclosed upfront with nothing added at checkout, so a ceiling can be netted into hammer terms before the sale.
Documented condition. Every lot carries a three-page professional condition report. In the Contemporary Art Spring 2026 sale of 26 May 2026, 25 lots were offered and 23 sold, for approximately €39,480 in gross hammer.
Register for the Contemporary Art Summer 2026 sale and join the LLB Auction list to receive each catalogue, with estimates and condition reports, before bidding opens.
Conclusion
Most bidders read the increment table once, at registration, and never return to it. Treated as an instrument, the answer to what is bid increment at auction becomes a working method: convert the ceiling into countable raises, net it of the premium, locate the band boundaries, enter near the top of a tier, and use a skipped round to test whether the bidder opposite is buying with conviction or with momentum. The arithmetic is best done in the hour before the sale, when there is time to check it. For the discipline that surrounds it, our guide to bidding with a cool head in the saleroom sets out the rest.
Also worth reading:
- Bidding With a Cool Head: Strategy and Self-Control in the Saleroom
- The Psychology That Makes Smart Collectors Overpay
- Setting Your Ceiling: a Method for Deciding What a Work Is Worth to You
- Enchérir sans se laisser emporter : méthode et sang-froid
Sources:
- UK Auction Buyer's Guide : Phillips, effective 12 April 2026
- Buying at Auction, Guide for Buyers : Sotheby's, 2023
- Strategic Jump Bidding in English Auctions : Christopher Avery, The Review of Economic Studies, 1998
- The hidden messages behind jump bidding in auctions : IESE Insight, 2024
- The Art Basel and UBS Art Market Report 2026 : Arts Economics for Art Basel and UBS, 2026
- Bidding Increments : The Auction Collective, 2026
- Auctions 101: How Do Auction Bidding Increments Work? : Barnebys, 2024
- The Complete Glossary of Auction Terms You Should Know : Invaluable, 2024
