About Jeremy Singh

I'm Jeremy Singh, a running coach and ultrarunner, and I build and maintain everything on this site: every calculator, every explainer, and every training guide. Running Calculators is a project of Singhcredible LLC, my company.

Where the experience comes from

I've spent more than a decade in endurance sports, and these days my format of choice is the backyard ultra: a 4.167-mile loop at the top of every hour until you can't answer the bell. I've finished four of them, lasting 11, 9, 16, and 14 hours, and I'm training for my fifth in September 2026 with eyes on running through the night and into the sunrise. If you want to know what that training actually looks like inside a real life, I wrote about it in Training for a Backyard Ultra When You Have a Job and Kids.

That matters here because every tool on this site gets used in my own training and with the athletes I coach. The pace math, the heart rate zones, the fueling numbers: I don't publish a calculator I wouldn't trust at hour twelve.

How I coach

I coach busy adults, a lot of them parents like me, who want to get faster without training taking over their lives or breaking their bodies. My philosophy is consistency over intensity: the runner who stacks months of repeatable, mostly easy training beats the runner who alternates heroic weeks with injury layoffs, every time. Injury prevention comes first, because volume only compounds if you're healthy enough to keep depositing.

I'm also the coach behind Coach Carl, my AI running coach, which gives runners day-to-day coaching built on the same philosophy you'll find in these pages. And when someone wants a human in their corner, Resilient Runner is my 1:1 coaching practice.

Why this site exists

Running Calculators is a free, science-based set of tools designed to help runners of all levels train smarter. Whether you're planning your first 5K or chasing a Boston qualifier, the calculators give you instant answers on race pace, heart rate zones, aerobic fitness, fueling, and the strange math of ultras. The mission is simple: make exercise science accessible to every runner.

Every formula comes from the published exercise science literature, each calculator page documents how its numbers are produced so you can check the math yourself, and every formula is covered by automated tests with known inputs and outputs. All calculations run directly in your browser. No data is sent to servers, and we do not collect any personal information.

If a number on this site ever looks wrong to you, I want to know about it. That standard is the whole point.