Super simple Bitcoin converter with real-time rates

Hey everyone, I whipped this up over the weekend. It's a tool where you can convert any amount to or from BTC, or just check the current exchange rate. Give it a shot by entering how many Bitcoins you have and see how the dollar value changes (hopefully goes up) over time. You can also put in a USD amount to convert to Bitcoin (more currencies are on the way). Check it out at preev.com. Would love to hear your thoughts! Feel free to drop comments, questions, or any feedback. P.S. Support for Internet Explorer is kinda limited right now.

Nice! What is in demand is a widget that works on a third party site but allows me to enter values like what you have.

Thanks, I hadn't considered a widget, but it's definitely an interesting idea. Do you know who wants it specifically? I'll have a think about how I might build it and get back to you.

. Fennec - Making something simple is rarely easy. Your converter is nicely done. I want to encourage you to continue thinking and building as you have. So I've just now sent one Bitcoin to the address on your web page.

Marcus, Thanks so much for your kind words and donation! I want to help make Bitcoin more accessible to everyone (not just us techy folks), so I plan to continue building tools that are simple and easy to use.

This is very cool! I'm sure merchants could use this. One of the problems with BTC is the fluctuating price. I'd like to see USD automatically converted to BTC on merchant sites.

Thanks Electron! I think you're right about price fluctuations; after I build a widget I'll contact some merchants.

Nice project! How do you compute the current rate? If you want something a bit more robust than simply taking the last trades, I would suggest looking at what I did for the KDE widget: http://kde-apps.org/content/show.php?content=138572 (uncompress the archive, the code is inside and should be straightforward to understand).

Cheers stakhanov! Currently, it's simply using the last price on Mt Gox. I'm planning to alter the calculation to include other (higher volume) exchanges. I'm not at home right now, but I'll have a look at the code later. Thanks.

Hey everyone, Just a quick update, since I finally found some more time to work on this. I've added 7 major currencies (AUD, CAD, CHF, EUR, GBP, RUB, SEK) for a total of 8 including USD. Also a few other small improvements e.g added the calculation result in the tab title, so you can see the live amount while browsing other tabs. Again, all comments etc welcome. Cheers

This is exactly the type of tool merchants need. BTW, I've been trying to get the script to work and haven't had any luck. Maybe I don't know enough about Java.

I wish it had BRL... But nice anyway! Very elegant design!

The number of exchanges isn't that important.  Mt Gox has 90% of the volume. A better algorithm would be one which is volume weighted over a period of time.  Say in last hour there were 5 transactions. 1000 BTC @ $3.99  200 BTC @ $4.06  800 BTC @ $4.01     1 BTC @ $4.80 obviously the $4.80 is an abberation but it is what users would see.  Taking a weighted average (volume * price) / (total volume) = $4.01 (technically $4.005397). The only thing to consider is how large of a weighting period.  The shorter the period the more reactive the average.  The longer the period the more it smooths out the spikes but the longer it takes to react to sustained price action. For a more "immediate value" I think 1 hour would be good starting timeframe but you may need to adjust.

I never got around to creating a merchant tool, unfortunately. Which script are you referring to? Thanks! Shouldn't be too hard. I might have some time in the next week, so I'll see what I can do. You're right, the last price can be deceptive. I agree with your volume weighted average idea, I'll implement when I get a chance. Cheers guys!

Sorry, I confused your converter with this: http://sanescreen.org/converter/

This is great! Are you still working on this? (pleasepleaseplease) Could you include the data from http://bitcoincharts.com/markets/currencies/ ? It's available as JSON: http://bitcoincharts.com/t/weighted_prices.json

If you build a html widget I will stick it on http://bitcoin.me

You need to create a wordpress widget for this. I need it for http://www.bitcoinvalues.net/bitcoin-calculator-calculate-current-market-value.html

Would love this as a widget.

Having Localbitcoins in the mix is skewing the average high (349.9 makes average go to 243.2 with the rest ~224-227). I would have an average of the arbitraged exchanges (Bitstamp, Bitfinex, BTC-E, etc...) separate from the average of the in-person ones (Localbitcoins, Mycelium Local Trader if you can pull their data). It seems like every time I turn around, someone in Marketplace is saying they use preev, but the price skewing high means they get less BTC.