Commission, VAT and lot fees quietly add 20–30% to every auction win. Auction Bid Calculator shows your all-in cost — and what the lot is really worth on eBay and Amazon — right on the auction page, before you bid.
Works on BidSpotter UK, BidSpotter US and i-bidder · Free forever for auction & eBay maths
A clean sidebar that opens on any BidSpotter or i-bidder lot. Commission rates are read from the page automatically — no hunting through terms & conditions.
Hammer price + commission + VAT + per-unit maths, computed live as you type. The commission % auto-fills from the lot page. Know your walk-away number before bidding opens.
Free · UnlimitedThe full UK fee table — tiered final value fees, fixed order fees, regulatory fee, seller levels, international rates — for private and business sellers. With break-even and profit targets.
Free · UnlimitedType an ASIN, get live FBA fees, referral rates and the 30-day average Buy Box price. Instant net-profit and ROI verdict on flipping the lot to Amazon.
10 free / month · Unlimited on ProBrowse BidSpotter or i-bidder as normal. Click the extension icon and the calculator slides in beside the lot — commission % already filled in.
Enter your intended bid. Every fee is added instantly — with and without VAT, per unit if you're buying multiples.
Flip to the eBay or Amazon tab to see fees, margins, break-even and profit targets. Bid when the numbers say yes — walk when they say no.
Auction and eBay maths run entirely in your browser — they're free, forever, no account needed. Amazon checks use live market data that costs us real money per lookup, so those are metered.
Yes. The auction and eBay calculators run locally in your browser and cost us nothing to serve, so they're unlimited and free — no account required. Amazon checks call live market-data APIs that charge us per lookup, which is why they're metered: 10 a month free with an account, unlimited on Pro.
bidspotter.co.uk, bidspotter.com and i-bidder.com. The calculator opens on any lot page and reads the auction house's commission rate automatically where it's published. More platforms are on the roadmap.
We model the full UK rate card: tiered final value fees per category, the fixed order fee, regulatory operating fee, seller-level adjustments, international fees and VAT. Rates are served from our backend so updates reach you without an extension update. Estimates are for guidance — always confirm against eBay's own fee pages before making big decisions.
Never. Payments are handled entirely by Stripe, sign-in by Clerk — two of the most trusted names in the business. Card numbers never touch our servers. See the privacy policy for the full picture.
Yes — two clicks from the extension ("Manage subscription") into Stripe's self-service portal. You keep Pro until the end of the period you've paid for. No retention dark patterns, no emails begging you to stay.
Join the flippers who know their walk-away number before the auctioneer clears their throat.
Add to Chrome — free