Add a free cost calculator to your auction website

Show your buyers the total they'll pay before they bid, using your own buyer's premium and VAT. It's free, takes about two minutes, and works on any website that lets you add an HTML or embed block.

Why auction houses add it

Fewer surprises at invoice time. Buyers can see what a hammer price really costs, including VAT and any online fee, before they commit.
It answers the most common buyer question without anyone needing to phone or email you.
A budget mode. Buyers can enter the most they can spend and see the highest bid that fits.
No sign-up, no cookies, no ads in the calculator, and it works on phones.

Set up your calculator

Your auction house name (optional)

Shown above the calculator as "What you'll pay at ...".

Buyer's premium (%)

Online bidding fee (%)

Leave at 0 if you don't charge one.

How do you quote your rates?

Plus VAT (for example "25% + VAT"). VAT is added on top of your fees. Includes VAT (for example "30% inclusive of VAT"). No VAT is added to your fees.

VAT rate (%)

Is VAT charged on the hammer price (the winning bid)?

No. VAT applies only to your fees. Yes, on every lot. VAT is added to the hammer price as well as your fees. On some lots. Buyers get a tickbox to add it for lots where VAT applies.

Check your own terms of sale. If only some of your lots carry VAT on the hammer price, choose "On some lots".

Accent colour

What your buyers will see

Enter your buyer's premium above to see your calculator here.

Fit the box to its content automatically (recommended). This adds a small script that only resizes the box. If your website builder blocks scripts, the box simply keeps a fixed height.

Your code

How to add it to your website

Fill in your details above and check the preview matches your terms.
Select Copy the code.
In your website editor, add an HTML, custom code or embed block to the page where you explain your fees (most website builders have one), and paste the code in.
Save and view the page on your phone as well as your computer.

If your fees change, come back, enter the new figures and replace the code on your page.

Questions

Is it really free?

Yes. There's no charge, no account and no sign-up.

Does it track my visitors?

The calculator doesn't use cookies or analytics, and nothing your visitors type into it is sent to us. It loads from bidcalc.co.uk like any web page, so our web host may keep standard server logs. See the privacy policy.

What if our fees are tiered or vary by lot?

The calculator uses one percentage for the premium. If you charge different rates on different parts of the price, enter your most common rate and say so near the calculator, or email us.

What does the auto-fit script do?

It only resizes the calculator box to fit its content. It listens for height messages from bidcalc.co.uk, ignores everything else, and doesn't read or change anything on your page.

Can I change how it looks?

You can choose the accent colour, add your name, and show or hide the VAT-on-hammer tickbox. The layout stays the same so buyers recognise it.

Do I have to keep the BidCalc link?

We'd appreciate it. The code includes a small "Calculator by BidCalc" line under the box, which is how the tool stays free for everyone.

Who is responsible for the figures?

You are. The calculator does the arithmetic on the rates you enter, and shows an estimate. Check it against your own terms of sale, and update it when your fees change.

Will it keep working?

We intend it to, but the calculator loads from our website, so we can't guarantee it will always be available. It's provided as it is, without warranty, and we may change or withdraw it. BidCalc isn't affiliated with or endorsed by any auction house.

Need a hand?

Email info@bidcalc.co.uk and we'll help you set it up. Want to see what buyers get? Try the full BidCalc calculator, or read our guide to how a buyer's premium works.

Email info@bidcalc.co.uk