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Auction calculator

What the hammer price actually costs, and whether the money can be there in time

Two things end auction purchases. The first is the fees: a buyer's premium, an administration charge, the seller's legal costs and searches you did not commission, none of which are in the guide price. The second is the clock. Contracts exchange on the fall of the hammer and completion is usually twenty eight days, while bridging currently completes in forty six on average. This prices both problems.

For: Bidding at auction, in the room or online

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The lot
£
A marketing figure, and deliberately low on most lots to draw a room. The reserve can legally sit up to ten per cent above the top of a guide range, and often does.
£
Decide this before the room does. The single most expensive habit in an auction is bidding in round numbers past a figure you set on the way in.
What is it?
Traditional or modern method?
Contracts exchange on the fall of the hammer and completion is normally 28 days. Binding immediately, and there is no cooling off period.
Auction fees
None of these are in the guide price, and all of them are in the legal pack.
%
One to five per cent of the hammer plus VAT, and it is now charged on about 40% of UK auction listings.
£
Many auctions charge a fixed premium instead, commonly £1,500 to £5,000 plus VAT, whatever the hammer price. On a cheap lot that is the larger number by far.
£
£750 to £1,500 per lot in 2026, payable on the day and not refundable.
£
Buried in the special conditions of the legal pack. It is entirely normal and it is entirely non-negotiable once the hammer falls.
What you should spend before you bid
All of it is at risk if you are outbid, and all of it is far cheaper than the alternative.
£
The single most important money on this page. The pack contains the special conditions, the title, the tenancies and everything wrong with the property, and once the hammer falls you have bought all of it.
£
Sometimes in the pack and often out of date. A search pack older than six months is worth re-doing.
£
Auction stock is auction stock for a reason. A Level 3 survey at £786 on a property you do not win is the cheapest lesson available.
Getting the money there
d
Twenty eight on a traditional auction, fifty six on the modern method. Some lots specify twenty, and a few specify ten.
%
Ten per cent is standard, with a minimum of £3,000 to £5,000 on cheap lots. Non-refundable, and the seller can sue for their losses on top if you do not complete.
How you will fund it
The normal answer. It averages 46 days to completion across the market, which is longer than the deadline, so it has to be arranged before the sale rather than after it.
Have you started the finance already?
Starting on the day after the sale gives you 28 days to do something the market does in 46. This is how deposits get lost.
%
Bridging lenders usually work off the lower of the hammer price and the valuation, so a bargain does not automatically borrow more.
%
mo
What the hammer price actually costs£153,758£15,758 on top of a £138,000 hammer price, which is 11.4% again and none of it is in the guide. The guide was £120,000, so this bid is 15% above it. Your funding takes about 46 days against a 28 day deadline, which puts £20,898 at risk.
£18,312Payable on the day
£6,012Auction fees
£7,160Stamp duty
46 of 28Days to complete
Hammer price90%Auction fees4%Stamp duty5%Legal and survey2%
The timing does not work46 days vs 28
£20,898 is at risk: the deposit, the premium, the administration fee and everything you spent before bidding. The seller can also sue for their losses and re-sell the lot. Arranging the bridge before the sale rather than after it takes this to about 21 days and fixes it.
Payable on the day
Deposit£13,800
10% of the hammer price, by bank transfer or card in the room. Non-refundable from the moment the hammer falls.
Buyer's premium£3,312
2.4% of the hammer price.
Administration fee£1,200
On the day£18,312
Have this available before you raise your hand. There is no negotiation and no cooling off.
Payable on completion
Balance of the price£124,200
Stamp duty£7,160
Due within 14 days of completion, which on a 28 day auction is six weeks after the hammer.
Seller's legal costs£1,500
In the special conditions of the legal pack. Read them before you bid, because you are agreeing to them when you bid.
Your legal and search costs£1,800
Net bridge advance£84,630
Out of a £96,600 facility, after £4,232 of fees and £7,738 of retained interest. The whole bridge costs £11,970.
Balance you have to find£50,816
After the deposit already paid and any lending. This is the number that has to be in your solicitor's client account before the deadline.
Sanity checks
Extras against the hammer price11.4%
Bid the price you want to pay all in, less this. Bidding your all-in budget as the hammer price is the commonest mistake in the room.
Your bid against the guide15%
Guides are marketing figures set to fill a room. The reserve is the number that matters and it can sit up to ten per cent above the top of the guide range.
Realistic funding time46 days
Bridging averages 46 days to completion across the market. With the valuation instructed and the solicitor briefed before the sale it comes down to about three weeks.
At risk if you cannot complete£20,898
The deposit, the auction fees and everything spent before bidding, plus whatever the seller loses on a re-sale, which they can pursue you for.
Where these figures come from

Buyer costs. Buyer's premiums run 1% to 5% of the hammer plus VAT, or a fixed £1,500 to £5,000 plus VAT. Administration fees are £750 to £1,500 per lot in 2026. Buyer's premium structures now appear on about 40% of UK auction listings. On the modern method the reservation fee is typically £5,000 and non-refundable.

Timing. Traditional auctions exchange on the fall of the hammer with completion normally at 28 days. The modern method allows 56. Bridging finance completes in 46 days on average across the market.

Legal pack. A seller's legal pack costs them £300 to £600 to prepare, and the special conditions routinely pass their legal costs to the buyer.

On a traditional auction, contracts exchange when the hammer falls. There is no cooling off period, no subject to survey and no subject to finance: you own the risk from that moment, which is why the insurance should be arranged before the sale rather than after it. Everything wrong with the property is in the legal pack, and having a solicitor read it costs a fraction of what not having one costs. The modern method is a different animal with a non-refundable reservation fee that usually sits on top of the price rather than counting towards it. Guide prices are marketing figures and the reserve may be up to ten per cent above the top of a guide range. An estimate, not advice.

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