The stereotype of a Y Combinator founder goes something like this.

Programmer. Smart and driven. Went to MIT or Stanford, or else skipped college altogether. Able to live on a ridiculously low salary. Enjoys working 90 hour weeks.

And of course: Young. Early-to-mid 20s.

I almost didn’t apply for Y Combinator last year because I thought I was too old. I was 31 at the time. The application asks for age, and I figured they would just ignore anyone who wasn’t in their 20s. But friends of mine made it in to the summer class, and they were older than I was, so I thought I’d try.

Granted, it can be more difficult to do YC when you’re advanced in years, like myself. I have a wife, two kids, and a mortgage. But there are advantages to being a bit older too. Since applications are open for the Winter 2011 class right now, I thought I’d share my experience.

Here is a quick guide to doing Y Combinator in your 30s.

Does YC Accept Founders Older Than 30?

Yes. And according to Paul Graham, age is neither a penalty nor a bonus. He writes:

“I don’t actually know the numbers. We don’t keep track. But I know there haven’t been any with founders in their 50s, and only 2 or 3 with founders in their 40s or their teens. Most founders are in their 20s or 30s. Completely guessing, I’d say 15-20% have founders in their 30s.”

That was in 2009, so the numbers may have changed.

Basically, the age distribution of YC companies is pretty close to the age distribution of applicants. More YC founders are 25 than 35, but more 25-year-olds apply than 35-year-olds.

Paul has an essay where he says the ideal range to start a startup is 22-38. As far as I know, that isn’t a rule, just a suggestion. YC has accepted plenty of people younger than 22, and at least a few over 38.

I’m Over 30 and Want to Start/grow a Startup. Should I Apply to YC?

Sure. If you can be in the Bay Area for 4+ months (3 isn’t enough if you need to raise money), and if you think you’d benefit from some excellent mentoring, then take a shot.

How Can You Afford to Do YC When You’re So Old?

It isn’t easy. A team of three only gets $20K. For most people, that’s not enough to live on in the Bay Area. When you’re 21, you solve this problem by living cheaply. Cheap apartment, no office, eat inexpensive food, don’t travel, don’t buy stuff. A low burn rate is a huge advantage for a startup, and if you can keep that up after YC, you’re a step ahead of the old guys.

Living cheaply is a bit harder to do when you’re older; when you’re 31, you’re more likely to have a high burn rate (due to family, mortgage, or more expensive lifestyle, etc.). But at 31, you have some advantages, too, like savings.

If you’re a good programmer at 31, you’ve probably made a reasonable salary for at least a few years. I supplemented our meager YC funding with savings. I also had run a software consulting shop leading up to YC, so I even had a bit of income in during my YC months (as my employees finished up a few projects).

What Happens When Your Savings Runs Out?

You raise money, or get profitable. If your entire team can live on $5K/month, getting profitable is much easier than if you need $25K/month. So if your expenses are high, then you’re often forced to raise money rather than getting profitable immediately.

Personally, I love the idea of running lean, getting profitable, and avoiding big funding. It isn’t for everyone, but it resonates with me. But it’s really, really hard to do, especially when you have a team that needs near-market salaries. So paradoxically, raising money is the easier option for most of us.

But Raising Money is Still Hard. Isn’t That Risky?

Yes. It is risky to drop everything with just a few months of runway and hope to raise money quickly. If you can’t take that risk, don’t do YC, or do a startup that doesn’t need investment. Raising money is hard, uncertain, and can kill a startup. But running out of money is guaranteed to kill a startup, so raising money is often a good idea.

The good news is that Y Combinator does an amazing job of preparing founders to raise money. You get great mentoring (by YC itself, by YC alum, and even by unaffiliated angel investors), a small PR boost, and the opportunity to pitch 100 quality investors at Demo Day. No guarantees that you’ll raise money, but a lot of YC founders do.

Is It Easier or Harder to Raise Money in Your 30s?

I don’t think it makes a big difference. At the end of the day, investors are looking for strong founders and a giant opportunity. Young founders have some things going for them, and older founders have others.

What About Co-founders?

This is important. If you’re 31 and have enough saved up to work on your app for 6 months, but your co-founders don’t, that’s a problem. To some extent, your company’s runway is only as long as the shortest co-founder runway. If your runways are uneven, be sure you have a clear understanding up-front of what happens when the first runway runs out.

What About Spouse/kids/mortgage?

This is very situation-dependent. I have friends who could never do what I do, because their home lives wouldn’t support it, or they couldn’t swing it financially. But I have a very supportive wife, and a little bit of savings. This made YC possible for me.

Aren’t You Supposed to Pay Yourself Like $30K/year as a Startup Founder?

Yes and no. I think the rule of thumb is, “pay yourself as little as possible,” which equates to, “pay enough that finances won’t keep you from focusing on your startup.”

Investors understand this. If you have kids and your real burn rate is $90K/year, pay yourself $90K/year. If you pay yourself $60K, you’ll have trouble sticking with the startup for the long-term. But if you only need $30K/year and you pay yourself $60K, you’re doing your startup a disservice.

If that sounds unfair (“Why should I only take $30K when the founder down the block is taking $90K?”) remember that if you take a low salary, you have an immediate advantage over the founder who needs a big paycheck. All else being equal, your startup is less likely to die than the expensive startup down the block—at least early on. If you have a team of 15 and VC funding, by all means, take a real salary.

Do People Look At You Funny Because You’re So Old?

No. Believe it or not, many startups have founders in their 30s or 40s. I even hear that there are people in their 50s doing startups. Shocking, I know.

Actually, it turns out that the 22-year-old founder/prodigy is the exception, not the rule. Based on a study of 549 entrepreneurs, the average age of a founder starting a “high-growth company” is 40, not 25. This is partly true because most of us aren’t prodigies, so we need a decade or two of experience and failure before we start to figure things out. But I think the biggest reason is simple: Founders don’t stop with one startup. If you enjoy starting a company at 25, there is a good chance you’ll enjoy starting one at 40 too.