I bid $5.50 on a rug. I paid $8.01. I built a calculator.
That's the whole origin story.
Works on any browser. Install it on your phone like an app — no App Store needed.
BidFTA stacks fees in a way that turns a "great deal" into a "wait, how much?" moment at checkout. This calculator shows you the real number before you commit — and a few things beyond that.
Auction mode Enter your bid → get the actual charge. Covers the 17.25% buyer's premium, freight surcharge ($1.00 for items ≥ $5, $0.25 for items under $5), and 7.5% sales tax. No surprises.
Bins mode Simpler. Just the price plus tax. No premium, no freight.
Reverse calculator Have a hard budget? Enter your max spend and it works backwards to tell you the highest bid you can safely place. Useful when you're determined not to go over $40 on a blender you don't need.
BidFTA link auto-fill Paste a BidFTA item link and it pulls the item name, current bid price, and MSRP directly from BidFTA's API. No typing, no copying. Just paste and go.
Deal comparison Enter what the same item sells for on Amazon, Walmart, or wherever. Hit the Search Amazon button and it opens a search in a new tab so you can grab the price quickly. The calculator then tells you whether you're actually saving money — and flags the no-warranty situation when the savings are slim.
Session tally Watching multiple lots in one session? Add items as you go and track your total spend before the auctions end. Each item stores the full fee breakdown — tap to expand. The grand total updates live.
Dark / light mode Because sometimes the good deals happen at midnight.
This is a PWA (Progressive Web App) — it installs directly from the browser, no App Store required.
Android (Chrome) Visit the link → tap the three-dot menu → "Add to Home Screen"
iPhone (Safari) Visit the link → tap the Share button → "Add to Home Screen"
Once installed it gets its own icon, runs fullscreen, and works offline.
I shop BidFTA regularly. The fee math isn't complicated, but doing it in your head mid-auction — on your phone, while the countdown ticks — is annoying enough that I kept getting it wrong. Now I don't.
It's a personal tool. I made it public in case anyone else finds it useful. If the fees change and I haven't updated it yet, feel free to open an issue.
| Fee | Amount |
|---|---|
| Buyer's Premium | 17.25% of bid |
| Freight (bid ≥ $5) | $1.00 flat |
| Freight (bid < $5) | $0.25 flat |
| Sales Tax | 7.5% of subtotal |
Fees can change. Always verify at bidfta.com before trusting any calculator, including this one.
Vanilla HTML, CSS, and JavaScript. No frameworks, no npm, no build step, no backend.
| File | What it does |
|---|---|
index.html |
The whole app |
manifest.json |
Makes it installable as a PWA |
sw.js |
Service worker — handles offline caching |
icon-192.png |
App icon |
icon-512.png |
App icon (large, for splash screens) |
Item data (name, current bid, MSRP) is pulled from BidFTA's API. Everything else runs locally in the browser. No data is collected or stored anywhere.
Personal project. Not affiliated with or endorsed by BidFTA.