ABOUT THE LAB

E85 Blend Lab is a free set of tools for people who run ethanol blends: a blend calculator that tells you exactly what to pump, a cost-per-mile page that tells you whether it's worth it, and guides that skip the forum folklore.

HOW IT'S BUILT

The site is plain HTML, CSS, and JavaScript — no accounts, no build step, no tracking. It installs as an app and works offline at the pump. The blend and cost math is open: the entire source lives on GitHub, tests included, if you want to check our arithmetic or file an issue.

WHERE THE DATA COMES FROM

• Flex-fuel compatibility — queried live from the US EPA's fueleconomy.gov web services, covering every US-market vehicle since 1984, engine by engine.
• Fuel energy figures — standard heating values (gasoline ≈ 114,100 BTU/gal, ethanol ≈ 76,100 BTU/gal) behind the cost-per-mile and break-even math.
• Tank sizes — a curated dataset of popular platforms; always approximate, always verify in your owner's manual.

HOW IT'S FUNDED

Some guides link to gear on Amazon (test kits, OBD adapters, flex-fuel parts). As an Amazon Associate, the site earns from qualifying purchases — at no extra cost to you. That's the entire business model; there are no ads, sponsorships, or paywalls. See the privacy page for the full data story (spoiler: we don't collect any).

THE FINE PRINT

Everything here is an estimate to help you plan a fill — not fueling, tuning, or mechanical advice. Verify tank capacity, fuel-system compatibility, and actual ethanol content before running high blends, and work with a tuner who knows your platform.