BTC DCA Engine: Bitcoin, gold, stocks and housing on one honest chart

BTC DCA Engine is a dollar-cost-averaging simulator I build and run at btcdcaengine.com. Dollar-cost averaging means buying a fixed amount on a fixed schedule, whatever the price. The simulator takes one schedule of buys and runs it against real daily prices, for Bitcoin and for eight other assets, and shows what each would be worth today in plain dollars, on one chart.

Why build another Bitcoin calculator?

Because every Bitcoin calculator I found answers the same narrow question: what would Bitcoin have done? They show Bitcoin against Bitcoin. That tells you nothing about whether the money would have been better off somewhere else.

The comparison people actually want is Bitcoin against gold, against the S&P, against the house they didn't buy. Nobody builds it, because those assets don't share a unit. You can buy a fraction of a coin every week. You can't buy a corner of a house.

I wanted this comparison myself. Since late 2024 I've worked with Joel Bomgar, a Bitcoin enthusiast here in Mississippi, and after trying the popular dollar-cost-averaging calculators I kept hitting what they couldn't do: put Bitcoin next to unlike assets and replay how each would have done over the same years. So I built the one I wanted. I see it mainly as a teaching tool. It lets people check Bitcoin's track record for themselves, then make their own decision about learning more, or buying some.

How do you compare a coin with a house?

You stop thinking in shares and start thinking in units.

Every contribution buys a fractional unit of the asset: the dollars you put in, divided by that day's price. Put $50 into something trading at $100 and you've bought half a unit. Keep doing that on schedule and the units add up. Multiply the units you've accumulated by today's price and you have today's value, in dollars.

That arithmetic doesn't care what the asset is. It runs the same way for Bitcoin, gold, a stock index and a housing series. So for the first time they can sit on one axis, and the axis is logarithmic, which means equal percentage moves take up equal space. An asset that grew many times over doesn't flatten everything else into a line along the bottom.

Same dollars in, same days, same measure out. That's the whole idea.

What's in it?

• 22 assets, compared on one identical schedule of buys.
• Real daily prices back to 2015.
• A shareable link for every run. The link reproduces the exact result against the same data, so a result you send someone is the result they see.
• Free to use. A Pro tier adds inflation-adjusted returns, risk metrics, and up to five strategies side by side.

It compares 22 assets. Seven are free: Bitcoin, Ethereum, Solana, XRP, the S&P 500, the Nasdaq 100 and gold. Pro adds the other 15: the Dow, silver, oil and bonds; Apple, Microsoft, Google, Amazon, Nvidia, Meta and Tesla one by one; commercial real estate; U.S. housing, nationally and for every state; and a CD and a 529 plan, modeled at average rates. Pro is $9 a month or $79 a year.

It's worth saying plainly what it isn't. It shows what a schedule of buys would have done on real past prices. It doesn't predict what any asset will do next.

What did building it teach me?

Two decisions carry most of the weight in this product.

The first is units instead of shares. Without it there's no comparison at all, just 22 calculators that happen to be on the same page. Once every asset is measured the same way, the chart does the arguing and I don't have to.

The second is tying every shared link to the data it was computed against. The data keeps growing as new days are added. A link that silently recalculated would show different numbers to different people at different times, and a comparison tool that can't reproduce its own answers isn't worth sharing.

The feedback that surprised me most came from people who never open the web app. They connect their own AI agent to BTC DCA Engine's MCP server and talk through simulations with it. What they tell me they like is the scenarios their agents think to run, and the link to the full results page that comes back with every run.

If you've ever wondered whether your regular Bitcoin buys beat what the same money would have done in gold or an index fund, that's the question it answers. It's free at btcdcaengine.com.

Stack: real daily price history back to 2015, a logarithmic dollar chart, and shareable run links tied to the data they were computed against. It's plain JavaScript and Tailwind, built by a small custom script, with prices from Yahoo Finance and housing and inflation data from FRED. It runs on Cloudflare Pages with Pages Functions; Supabase handles accounts and Stripe handles Pro billing.