Quick Answer: The course matters more than most first-timers expect. Elevation is the biggest single factor - a hilly half can cost five to fifteen minutes over a flat one for the same fitness. After that: surface (road is fastest, trail is slowest and hardest to pace), field size (a crowded start can cost two to three minutes in the first mile), start time and season (heat is the great equaliser downward), and how much of it is out and back on a road you have already run. Choose the course for your goal, not for the medal - and if this is your first, choose flat, well-organised, and cool.

Right now is when spring races open and autumn races are being run, so it is a good moment to look properly at what you are entering.

How much does elevation actually cost you?

More than almost anything else, and it is the number people check least carefully.

A useful rule of thumb: roughly 10-15 seconds per mile for every 100 feet of climb - but that badly understates a hilly course, because you never get it all back on the descent. Downhill running does not return the time uphill running takes, and it costs you far more in quad damage.

Practically: a genuinely flat half - under about 200ft total gain - is a fast course. 200-500ft is rolling and costs a modest amount. Over 800ft is a hilly race, and expect five to fifteen minutes slower than your flat time depending on how the climbs are distributed.

Distribution matters as much as total. One long steady climb is easier to run and easier to pace than the same elevation as twenty short sharp hills, which repeatedly break your rhythm and hammer your legs.

Where the hills sit matters most of all. A climb in the last three miles is disproportionately expensive because you meet it already fatigued. Check the profile, not just the total.

How to check properly: every well-run race publishes an elevation profile. If they do not, that is itself information - and you can usually find the route on a running app where somebody has recorded it. Look at the profile shape, not the headline number.

What else about the course changes your time?

Four things, and all of them are knowable before you enter.

Surface. Road is fastest. Well-maintained gravel path is slightly slower. Trail is substantially slower and much harder to pace, and a wet trail race in autumn is a completely different event to the same course in June. Mixed-surface races are fine but expect the transitions to break your rhythm.

Turns. A course with many tight turns is slower than a straight one - you lose momentum at each one, and in a crowded field you lose more. Loop courses with repeated turns are noticeably slower than point-to-point.

Field size and start structure. A big race with proper pen or wave starts is fine. A big race without them means two to three minutes lost in the first mile weaving. A very small race has the opposite problem - you may run large sections alone, which is mentally harder and costs you the pacing benefit of a group.

Out-and-back sections. Fast and simple to organise, and psychologically harder - you see the leaders coming back, and you run a road you have already run. Some people are fine with it; some find mile 10 on a familiar road demoralising. Worth knowing which you are.

And the one nobody checks: what the last mile looks like. A finish uphill, into wind, or on a different surface is where races are lost.

Does the date and start time matter?

Considerably, and it is the easiest thing to get right.

Temperature is the big one. Performance drops measurably above about 12-15C, and by 20C most runners are meaningfully slower - commonly 2-4% over a half marathon, which is three to six minutes for a two-hour runner.

Which makes autumn and spring races the fast ones. October and April races are typically the best conditions in most of the northern US and northern Europe. Summer races are for the experience, not the time.

Start time follows from that. An 8am start is cooler than a 10am start, and on a warm day that difference is real. Early starts are also less likely to be affected by wind, which usually builds through the morning.

Think about the training season, not just the race day. An October race means training through August heat; an April race means training through winter dark and ice. Both are hard in different ways, and it is worth choosing the one that suits your circumstances rather than the one with the nicer race-day weather.

Travel and logistics count. A race that needs a 4am start and two hours of driving costs you sleep, and sleep the night before matters. A local race you can walk to is worth a minute or two on its own.

For a first half specifically: pick something in spring or autumn, close to home, with an early start. Everything else is secondary.

5 Mistakes People Make Choosing a Race

1. Choosing on the medal or the photos. It sounds trivial and it is genuinely the most common selection criterion. A scenic coastal race is often a windy, hilly, exposed race, and the reason the photos look good is precisely the reason it is hard.

2. Not checking the cut-off time. Many races have one, typically three to three and a half hours for a half. If you are a first-timer aiming to finish comfortably, check this before entering - it is dispiriting to be swept, and some races reopen roads behind you.

3. Choosing a first race that is too big or too small. A very large city race is overwhelming for a first-timer - the logistics, the crowd, the pen system. A very small one leaves you running alone. A field of one to three thousand is the sweet spot for a first.

4. Ignoring the aid station plan. How many stations, what they serve, and whether they have gels all matter, and races vary hugely. If a race is cupless - increasingly common - you must carry your own bottle, and finding that out on race morning is a bad way to start.

5. Entering too soon after another race, or too late in a training block. You need twelve to sixteen weeks of preparation for a first half. Count backwards from the date before you enter, not after. And if the race is more than four months out, you may peak too early.

How should you match the race to your goal?

Different goals want genuinely different races.

First half, aiming to finish: flat, well-supported, mid-size, spring or autumn, close to home. Generous cut-off, plenty of aid stations, and a course you can drive or run part of beforehand. Do not choose a trail or a hilly race for your first - the experience is worth having, but not as an introduction.

Chasing a specific time: flat, road, point-to-point or a simple loop, wave start, cool morning. Look for races with a reputation for being fast - the runner reviews will tell you within two minutes of reading.

Wanting the experience: big city races, destination races, and scenic courses. Accept that the time will be slower and enjoy what you came for.

Building toward a marathon: choose a half that mirrors your target marathon’s terrain and conditions. A hilly half is genuinely useful preparation for a hilly marathon.

Coming back from injury or a break: flat, small, low pressure, and generous cut-off. Give yourself a course that lets you run conservatively without feeling like the last person on it.

A practical last step whatever your goal: read three race reviews from runners at roughly your pace. They mention the things the race website never does - the mile-11 hill, the bottleneck at mile 2, the finish that is further from the car park than advertised. It takes ten minutes and it is the most useful research you can do. This is general information, not medical advice - if you are returning from injury, get individual guidance before committing to a training block.

FAQ: Choosing a Half Marathon, Answered

How far in advance should I enter?

Twelve to sixteen weeks for a first half, so the training block fits. Popular races sell out much earlier, so you may need to enter and then plan backwards - just check the date is far enough away when you do.

Is a flat course always better?

For time, yes. For your legs, a completely flat course is monotonous and uses the same muscles identically for two hours. Some runners actually prefer gently rolling.

What is a fast course, exactly?

Flat, road, few turns, wave start, cool conditions, and preferably slightly net downhill. Races that consistently produce personal bests are well known in local running communities.

Should my first half be a big city race?

It is a great experience but a harder introduction. Mid-size races are easier to navigate and you will spend less of race morning stressed.

What about virtual or unofficial races?

Fine for the distance, but you lose the aid stations, the field, and the atmosphere - all of which are worth several minutes. As a first, an organised race is a better experience.

How do I find the elevation profile if the website has no map?

Search the race name on a running app - someone will have recorded the route. If nobody has, and the race publishes nothing, take that as a sign about the organisation.

TL;DR:

• Elevation is the biggest variable - a hilly half can cost five to fifteen minutes. Check the profile shape, not the total, and look at where the climbs sit.
• Road beats trail, few turns beat many, wave starts beat mass starts, and out-and-back is psychologically harder.
• Cool matters - above 12-15C you slow measurably, so spring and autumn races are the fast ones.
• Check the cut-off time and the aid station plan before entering, especially for cupless races.
• First half: flat, mid-size, close to home, generous cut-off, twelve to sixteen weeks away.
• Read three race reviews from runners at your pace. It is the highest-value ten minutes of research available.

People spend sixteen weeks training and ten minutes choosing the race. Reversing a little of that ratio is one of the cheapest improvements available to a half marathon runner.