If you think you could save a lot on rent by moving out of La Jolla, you’re right. But if you think that by doing that, you could save a lot overall, think again.

Everyone knows that rent in La Jolla is expensive, but you’re paying for a prime location. You may have already noticed that the UCSD area is much prettier than, for example, El Cajon.

Rent is usually a person’s biggest monthly expense, so many assume that a lower housing cost equals a lower cost of living overall. On the surface, cheap rent can look like a great deal. In reality, it may be an expensive mistake.

It’s easy to be lured to an area because it has rock bottom rent. Most people have a psychological fear of spending a large amount of money at one time. Given a choice, most people would rather spend $300 instead of $700 at once, if the apparent item — in this instance, an apartment — were the same. But you need to look at more than just rent to know if you are living as cheaply as you think you are. You need to look at time as money, and vice versa.

When you live farther away from La Jolla, rent becomes less expensive, but driving here gets more expensive. Everything else — groceries, entertainment, clothing — costs about the same no matter where you live, so we only need to look at the factors with the biggest differences: rent and transportation. For the sake of simplicity, the transportation costs only include the cost of driving to and from school, not your trips to the store, to work or to the mall.

A typical three-bedroom apartment in La Jolla goes for $2,100 per month. If you want your own room, you pay $700 per month. You then drive about four miles round-trip to campus each day, or about 80 miles per month. At 50 cents per mile — accounting for maintenance, insurance, fuel and car payments — you pay about $40 per month to drive to school and $50 per month to park there. Your total cost for rent and transportation in La Jolla: $790 per month.

The lowest price you’ll find for a single bedroom in El Cajon is about $300 — many places are more expensive than that, but very few are cheaper — in a $900 per month three-bedroom residence. Here, you drive about 40 miles round-trip to campus each day, or about 800 miles per month. At 35 cents per mile (driving gets more economical over longer distances), you pay $280 per month driving to school, and $50 parking. Your total cost in El Cajon: $630 per month. At first glance, this seems nice: You have saved $160 per month by moving to El Cajon.

But at what cost?

If you’re lucky and you have a job that pays $10 per hour, you would need to work 79 hours every month (70 of them to pay for rent, nine to pay for your trips to school) to live in La Jolla. Your 80 miles of driving to and from campus takes a total of about seven hours. So you would spend 86 hours every month to live in La Jolla, two miles away from campus.

Working at that same $10 per hour job, you would need to work only 63 hours every month (30 of it to pay rent, 33 to pay for your trips to school) to live in El Cajon. But your 800 miles of driving every month tends to take about 33 more hours of your time. You spend 99 hours every month to live in El Cajon, 20 miles away from campus. By living in El Cajon, you have saved $160 per month at a cost of 13 hours of your time. You are effectively compensated for that extra 13 hours at a rate of $12.31 per hour.

If you hate your job but love sitting in traffic, El Cajon could be right for you. If your job is so great that you actually enjoy working there and would rather not waste 33 hours sitting in traffic, La Jolla might be a better bet.

Let’s return to location: La Jolla is close to the beach and its weather is temperate. El Cajon is 20 miles away from the beach and in the desert, where it is often 80 degrees during the day and 40 degrees the same night. If you live in La Jolla, you might go to the beach or just exercise more often, since it’s more convenient and comfortable to do so. At the very least, you’ll save money on utilities, since you won’t be air-conditioning your apartment as often. Your savings can diminish rapidly thanks to extra utility costs.

Some more on location: If you live in El Cajon, you have no practical choice but to drive to UCSD. Even with a car, 20 miles is a long way. If your car breaks down, you can’t get to school very easily. Even a die-hard transit rider or bicyclist won’t do a 40-mile round-trip to and from campus.

If you live two miles away, you can choose from driving, taking the bus — UCSD provides a free bus pass for routes near campus — or riding your bike. You could even walk to the Regents parking shuttle and take that the rest of the way to campus. You could also save $50 per month on a parking permit — or more, if your car ever gets ticketed — by walking or bicycling.

What if you forget something important at home or you realize you need to study at Geisel Library on a Saturday? From La Jolla, the extra drive costs you $2; from El Cajon it costs $14. Also, the shorter trip only requires one hour of your time instead of three — remember that you need to account for the time spent driving and the time you work to pay for the trip.

On environmental impact: Driving those extra 720 miles per month really hurts the environment. We’re not just talking about your tree-hugging, dirt-worshipper definition of “”environment”” here. Obviously, more driving creates more pollution. But the extra traffic generated by thousands of people who think it’s a great idea to live 20 miles away from work or school also clogs San Diego’s streets, creates more noise, devours land for more streets and parking lots, and increases the number of vehicle collisions. In short, when so many people do it, it sharply decreases the city’s quality of life.

The earlier examples assumed that you were paying for a single room. If you live in a shared room, slash the rent figures in half so that you pay $350 per month in La Jolla and $150 per month in El Cajon. The rent is cheaper, but the driving costs stay the same.

Living in La Jolla now costs just $440 per month. Get ready for a shock: Living in El Cajon now costs $480 per month. You’re not only spending more money to live there, but also spending four extra hours at work and 26 extra hours in traffic to do it. Suddenly, paying $150 a month for rent doesn’t look so great.

Living far away for “”cheap rent”” does not always save time or money, often ends up costing you more of both, and always ends up costing society more.

The bottom line is that you really need to do the math before deciding where to live. Calculate all your expenses, not just rent, and calculate the cost to society, not just your own.