How to Build Your Race-Day Fueling Kit: What to Carry, Where to Stash It, and When to Use Each Item

You Have a Plan. Now What?

You've done the work. You know how many grams of carbohydrates per hour you need. You've picked your gels. You've trained your gut to handle 60–90g of carbs per hour without rebellion.

And then you're standing in your kitchen the night before the race, staring at a pile of gels, a flask, salt tabs, and a race belt — wondering how any of this is supposed to fit on your body while you run 26.2 miles.

This is the gap nobody talks about. Every training plan, nutrition guide, and sports science article tells you what to eat and when to eat it. Almost none of them tell you how to carry it all and how to access it without losing 30 seconds at mile 16 because your gel is stuck to the inside of your shorts pocket.

This guide fixes that.

Step 1: Calculate What You Actually Need to Carry

Before you can build your kit, you need to know what's going into it. The number of items you carry depends on three things:

Your carbohydrate target per hour. Most runners should aim for 60–90g of carbs per hour during a marathon. For a half marathon, 30–60g per hour is typical. Your exact target depends on your body weight, training volume, and how well you've trained your gut.

Your finishing time. A 3:15 marathoner is fueling for roughly 3 hours of effort. A 4:45 marathoner is fueling for nearly 5 hours. Slower runners need more total fuel, not less — a point that surprises a lot of athletes.

What you'll get from aid stations. Most major marathons offer water and a sports drink (often Gatorade or a sponsor brand) at regular intervals. Some offer gels at specific miles. Check your race's nutrition plan and subtract what you can reliably grab from aid stations.

Here's a practical example. A 4:00 marathoner targeting 60g of carbs per hour needs about 240g of carbohydrates across the race. If each gel contains 25g of carbs, that's roughly 9–10 gels. If aid stations provide sports drink every 5km that you can grab reliably, that might cover 15–20g per hour, reducing your gel count to 6–7.

That's still a lot of gels to carry on your body.

Step 2: Choose Your Carrying System

There are four main options, and most runners use a combination.

Race belt or running belt

A thin elastic belt worn around your waist with small loops or pockets for gels. The most popular option for marathoners. Good belts sit flat against your body without bouncing. Look for one with 4–8 gel loops and a small zip pocket for salt tabs or cash.

Best for: Marathoners carrying 5+ gels who want easy mid-run access.

Watch out for: Cheap belts ride up or bounce. Test it on at least two long runs. Tighten it more than you think — it loosens as you sweat.

Shorts pockets

Many running shorts now come with built-in gel pockets on the waistband or thigh. If your shorts have good pockets, you might not need a belt at all for a half marathon (2–4 gels). For a full marathon, shorts pockets work as a supplement to a belt.

Best for: Half marathoners or runners carrying fewer than 4 gels.

Watch out for: Gel wrappers get sticky and hard to open when they've been pressed against sweaty fabric for two hours. Pre-tear the tops before the race.

Handheld flask

A soft flask (200–500ml) held in your hand or strapped to it with a velcro grip. Fill it with your preferred electrolyte mix so you're not dependent on whatever the aid stations offer. Some runners carry two — one for water, one for electrolyte drink.

Best for: Runners who want precise control over their electrolyte mix, or races where aid station spacing is unpredictable.

Watch out for: Carrying something in your hand for 3–4 hours changes your arm swing and can cause tension in your shoulders. Switch hands regularly. Practice this in training.

Drop bags (if allowed)

Some races let you leave a bag at a specific point on the course (often the halfway mark). This is your mid-race resupply. Pack fresh gels, a full flask, salt tabs, and even a spare gel wrapper disposal bag.

Best for: Ultra marathons and races that support drop bags. Also useful for marathoners who don't want to carry everything from the start.

Watch out for: You're dependent on race logistics. If you miss your drop bag or the station is crowded, you're stuck with whatever you started with.

Step 3: Build Your Kit by Race Distance

Half marathon (1:30–2:30 finishing time)

You need 60–120g of total carbohydrates. That's 3–5 gels.

Carry:

• 3–4 gels in your shorts pockets (pre-tear the tops)
• 1 soft flask (250ml) of electrolyte mix if you prefer your own over aid station sports drink
• 2 salt/electrolyte tabs in a small zip-lock bag pinned inside your waistband

Kit weight: Under 200g. No belt required for most runners.

Marathon (3:00–5:00 finishing time)

You need 180–400g of total carbohydrates. That's 7–16 gels (assuming 25g per gel), minus whatever aid stations provide.

Carry:

• Race belt with 5–7 gels loaded in the loops
• 1–2 additional gels in shorts pockets as backup
• 1 soft flask (300–500ml) of electrolyte mix
• 4–6 salt/electrolyte tabs in the belt's zip pocket
• 1 empty gel wrapper in a pocket (use it as a bin — don't litter the course)

Kit weight: 300–450g. Feels like nothing after the first mile.

Ultra marathon (50k+)

Drop bags change everything. You don't carry your full race fuel — you carry enough to get to the next resupply point.

Carry between aid stations:

• 3–5 gels or equivalent real food (rice balls, PB&J bites, dates)
• 1 soft flask (500ml) of electrolyte mix
• Salt tabs in a zip-lock
• Consider a small running vest if carrying more than 1L of fluid

In each drop bag:

• 5–8 gels or food items
• 1 full flask of electrolyte mix (pre-mixed)
• Salt tabs
• Backup: a few sweets or salty crisps for when gel fatigue hits

Step 4: Pre-Race Prep Ritual

The night before the race, lay out your entire fueling kit. This isn't just organisation — it's a confidence-building exercise. You want zero decisions on race morning.

Pre-tear every gel. Tear the top corner of each gel just enough that you can rip it open with your teeth mid-stride. If you have to fight a gel wrapper at mile 20, you've already lost 10 seconds and a chunk of your mental energy.

Label your gels by mile. If you're taking a gel every 5 miles, write the mile number on each one with a Sharpie. Load them into your belt in order. When you reach mile 10, you grab the gel that says "10" — no thinking required.

Pre-mix your flask. Don't wait until race morning to measure electrolyte powder. Mix it the night before, cap it, and refrigerate it. One less thing to think about at 5am.

Pin your salt tabs. Put them in a tiny zip-lock bag and pin it to the inside of your belt or waistband. Loose tabs in a pocket will dissolve in your sweat before you need them.

Do a body check. Put on your exact race-day outfit with your belt, flask, and all gels loaded. Stand in front of a mirror. Jump up and down ten times. If anything bounces, shifts, or digs into your skin, fix it now.

Step 5: Mid-Race Execution

Having the kit is half the battle. Using it efficiently is the other half.

Set a fueling alarm on your watch. Every 20–30 minutes or every 5km — whichever matches your plan. When the alarm goes off, eat. Don't negotiate with yourself. Don't wait until the next aid station. Don't skip one because you feel good. Consistency is the entire game.

Practise the grab-tear-squeeze-toss sequence. Reaching for a gel, tearing it open, squeezing it into your mouth, and disposing of the wrapper should be a fluid motion you can do without breaking stride. This sounds silly to practise. It isn't. At mile 22, when your fine motor skills have degraded and your hands are slippery with sweat, you'll be glad you rehearsed it.

Take gels with water, not sports drink. If you wash down a 25g carb gel with a cup of sports drink, you're spiking your carb intake for that window and risking GI distress. Pair gels with plain water. Use sports drink between gels if you want the extra carbs.

Have a backup plan. If you drop a gel or your flask leaks, what's your fallback? Know which aid stations have gels. Know which offer sports drink vs water. A 30-second pit stop to grab an extra cup of Gatorade is better than running the last 10km under-fueled.

Step 6: Test Everything in Training

This is the rule that separates athletes who execute their fueling plan from athletes who bonk despite having one: nothing new on race day.

Your fueling kit should be race-tested on at least three long runs before the event. Not just the gels — the entire system. The belt. The flask. The shorts. The grab-tear-squeeze sequence. The watch alarm.

Each long run rehearsal, pay attention to:

• Does the belt bounce or chafe after 90 minutes?
• Can you open gels with sweaty hands?
• Is the flask easy to drink from without stopping?
• Do the salt tabs survive in their pouch or dissolve?
• Can you hit your carb target per hour consistently?

If something doesn't work, you have weeks to fix it. On race day, you have zero.

The Missing Piece: Knowing Exactly What Your Kit Should Contain

Everything in this guide assumes you already know your carbohydrate target per hour, your electrolyte needs, and which products work for your stomach. That's the hard part — and it's personal.

Your sweat rate, body weight, finishing time, and training load all affect what goes into your kit. A 65kg runner doing a 3:30 marathon in cool conditions needs a different kit than an 85kg runner doing a 4:45 marathon in May heat.

Sweatr calculates all of this from your Apple Watch, Garmin, and Strava data. It builds your personalised fueling plan — how many grams of carbs per hour, how much sodium, how much fluid — and maps it to specific products you can buy. Your fueling kit list isn't a guess. It's calculated from your actual data.

The logistics of carrying and executing that plan? That's what this guide is for. The plan itself? That's what Sweatr is for.