Auction Buyer's Premium Calculator: Premium and Total Cost
Work out the buyer's premium on a winning auction bid and what you'll actually pay — the surcharge that turns a 'great deal' hammer price into a meaningfully larger total.
Adjust the inputs and select Calculate for a full breakdown.
Compare Common Scenarios
How the numbers shift across typical situations for this calculator:
| Scenario | Buyer's premium | Total you pay |
|---|---|---|
| 20% on $5,000 | $1,000.00 | $6,000.00 |
| 25% on $2,000 | $500.00 | $2,500.00 |
| 27% on $50,000 (fine art) | $13,500.00 | $63,500.00 |
| 12% on $800 (estate auction) | $96.00 | $896.00 |
How This Calculator Works
Enter the hammer price (your winning bid) and the buyer's premium rate. The calculator multiplies the two to give the premium and shows the total you'll pay. Sales tax and shipping are additional — budget for those on top of this figure.
The Formula
Percentage Add-On
Rate is the tax or tip percentage applied to the amount
Worked Example
A $5,000 winning bid at a 20% buyer's premium adds $1,000, for a total of $6,000 before tax and shipping. Bidders who anchor on the hammer price routinely overpay because the premium is invisible until checkout — a 25% premium plus 8% sales tax turns a $5,000 bid into $6,750. Always set your maximum bid net of the premium you'll owe.
Key Insight
The buyer's premium is auction houses' primary revenue source — and the most-overlooked cost by casual bidders. At a 25% premium, every $100 of bidding costs you $125 before tax. The correct bidding discipline: decide the maximum total you'll pay for an item, then work backward to set your hammer-price bid cap (max total ÷ 1.25 for a 25% premium). Bidders who set their cap on the hammer price alone consistently blow their budget by the premium amount. Premiums have crept up over the decades — what was 10% in the 1990s is 25%+ at major houses today.
How buyer's premium has crept upward — from 10% to 30%
The buyer's premium was introduced by Christie's in 1975 at 10% — a controversial move at the time, since auction houses had historically been paid only by the seller's commission. By 1990 the rate had risen to 15% at major houses; by 2010 to 20-25%; by 2024 the headline rate at Christie's and Sotheby's reached 26-27% on the first tier (under ~$1M). The trend has been continuous upward pressure with no reversal episodes.
Drivers of the increase: (1) competitive seller's commission compression — wealthy consigners negotiate lower or zero seller commission, forcing auction houses to extract more from buyers; (2) operational cost increases — physical auctions, expertise, marketing, fraud / authenticity overhead have risen with art-market sophistication; (3) demonstrated buyer inelasticity — buyers continue to bid despite the premium being a known cost, suggesting that art-market buyers are relatively price-insensitive at the gavel.
For buyers: the buyer's premium is a real cost that should be calculated INTO the bid. A 25% premium means a $100,000 hammer price costs the buyer $125,000 + tax = $135,000-$140,000 all-in depending on state. Bid limits should be set on the all-in cost target, not the hammer-price target — a common error among new auction participants is bidding to a hammer-price limit and getting surprised by the premium.
Sales tax and collectibles capital gains — auction-specific tax treatment
U.S. sales tax applies to auction purchases when the lot is delivered to a state with sales tax. Major auction houses collect tax on delivery state, not auction location. For high-value purchases ($25K+), buyers commonly route delivery to a 'freeport' (Geneva, Singapore, Delaware, Wyoming) to defer sales tax until the work is shipped to a taxable destination — a legal but criticized practice.
Capital gains on collectibles (art, antiques, gems, stamps, coins, comic books, sports memorabilia) sold at auction face a higher federal tax rate than standard capital gains: up to 28% (vs 20% for stocks and most other long-term gains). The 28% rate is set by Section 1(h)(5) of the Internal Revenue Code. State capital gains apply additionally (varies 0-13.3%). Combined federal + state collectibles capital gains tax can exceed 40% for high-bracket sellers — a meaningful tax cost when selling appreciated collectibles.
For buyers planning to hold long-term: the 28% collectibles tax is a real cost compared to other asset classes (stocks at 20%, real estate at 20%, qualified business interests at 20%). This contributes to the unique economics of art and collectibles as an asset class — high transaction costs (buyer's premium 25%, seller's commission 10-20%, capital gains 28%) mean nominal price appreciation must substantially exceed inflation to produce real net returns to the investor.
Major auction house buyer's premium schedules (2024)
Reference buyer's premium rates for major U.S. and international auction houses. Tiered structure — premium percentage decreases on incremental amounts above thresholds.
| Auction house | Tier 1 (lowest) | Tier 2 | Tier 3 (highest) |
|---|---|---|---|
| Christie's | 26% to $1M | 21% $1M-$6M | 15% above $6M |
| Sotheby's | 27% to ~$1M | 21% $1M-$6M | 15% above $6M |
| Bonhams | 27.5% to $1M | 22% $1M-$6M | 15% above $6M |
| Phillips | 27% to $1M | 21% $1M-$8M | 15% above $8M |
| Heritage Auctions | 25% (most cats.) | — | — |
| Doyle / Bidder | 25% | — | — |
| Invaluable / LiveAuctioneers (platform) | +3-5% over the house premium | — | Additional online bidding fee |
| eBay (lot-listed) | 10-15% | — | Plus payment processing |
Premiums shown are headline rates; actual contracts may include category-specific variations. Online-only auction platforms (Catawiki, Auction Mobility) typically have flatter, lower premiums (10-20%) but smaller and less prestigious inventory. Buyer's premium is added to hammer price; sales tax applies to the sum where required.
Frequently Asked Questions
How is the buyer's premium calculated?
Multiply the hammer price by the premium rate. A 20% premium on a $5,000 winning bid is $1,000, for a $6,000 total before tax and shipping.
What's a typical buyer's premium?
Major houses (Sotheby's, Christie's, Bonhams): 20% to 27%, usually sliding-scale (higher rate on lower-value lots). Regional and estate auctions: 10% to 20%. Online platforms (eBay-style live auctions): 10% to 25%. Always check the specific auction's terms before bidding.
Is sales tax on top of the premium?
Usually yes. Sales tax typically applies to the hammer price PLUS the buyer's premium (the full purchase price), adding another 5% to 10%. Shipping, insurance, and any import duty are additional. The hammer price is often only 70% to 75% of what you actually pay.
How should I set my maximum bid?
Decide the maximum total you're willing to pay (including premium and tax), then work backward. For a 25% premium and 8% tax, divide your max total by 1.35 to get your hammer-price bid cap. Bidding to your max-total on the hammer price alone overspends by the premium and tax.
Why has the buyer's premium increased over time?
It's the auction houses' main margin lever, and competition for consignments has pushed seller's commissions down — so houses raised buyer's premiums to compensate. What was around 10% in the 1990s is 25%+ at major houses today, with periodic increases announced quietly.
When is this calculator unreliable?
When stacked online bidding platform fees apply (LiveAuctioneers, Invaluable add 3-5% above house buyer's premium), when cross-border purchases involve customs / VAT (5-25% additional), when sales tax routing matters (delivery state determines tax — high-value buyers may use freeport delivery), or when category-specific premium structures differ from the standard schedule (some specialty categories have lower premiums; some online-only categories have different fee structures). For high-value purchases, request the complete fee schedule in writing before bidding.
References & Authoritative Sources
- U.S. Internal Revenue Service (IRS) — Capital Gains and Collectibles Taxation · consulted June 1, 2026 · U.S. federal taxation of collectibles — capital gains rate up to 28% (vs 20% for stocks)
- Christie's — Terms and Conditions — Christie's Standard Buyer's Premium Schedule · consulted June 1, 2026 · Major auction house current buyer's premium rates
- Sotheby's — Buyer's Premium — Sotheby's Standard Conditions of Business · consulted June 1, 2026 · Major auction house buyer's premium and seller's commission disclosure
Related Calculators
Methodology & Review
Auction buyer's premium total equals the hammer price plus the buyer's premium percentage (typically 12-30% in 2024 at major auction houses) plus applicable sales tax. The calculator returns the total cost to the buyer including premium and tax. For some auctions, additional fees apply: online bidding platform fees (typically 3-5% above buyer's premium for third-party bidding platforms like Invaluable, LiveAuctioneers), import duties for cross-border purchases, and shipping. Major auction-house buyer's premium rates 2024: Christie's 26% on first $1M, 21% on next $5M, 15% above; Sotheby's similar tiered structure; Bonhams 27.5% / 22% / 15%; Heritage Auctions ~25% on most categories. RELIABILITY: Reliable for major-auction-house standard transactions where buyer's premium is the only above-hammer cost. Less reliable for online-platform auctions with stacked fees (eBay, Catawiki may add 5-8% above buyer's premium), for cross-border purchases where customs / VAT add 5-25%, or for category-specific auctions (real estate, automotive) where the premium structure can be very different.
Updated