Best Marathon Gels: Ranked by Carb Ratio and GI Tolerance

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Your gut can only absorb about 60 g of carbohydrate per hour from a single sugar source. Above that, the absorption pathway saturates and the excess ferments in the gut, causing bloating, cramps, and the kind of GI distress that ends races. The fix is a dual-transport gel that combines glucose (or maltodextrin) with fructose, which uses a separate intestinal transporter and raises the ceiling to 90 g per hour. Here is how the major gels stack up.

The best marathon gels in 2026

1. Maurten Gel 100 (best overall for race pace)

Maurten uses a hydrogel matrix that encapsulates carbohydrates in a polymer network, which delays breakdown and reduces osmotic load on the gut. The result is a gel that causes fewer stomach problems at race intensity than most alternatives. Each sachet delivers 25 g of carbohydrate at a roughly 0.8:1 glucose-to-fructose ratio, keeping total carbs below the single-sugar ceiling at normal dosing. Take one every 20 to 25 minutes for a 60 to 75 g per hour intake.

Carbs per sachet: 25 g Glucose:fructose ratio: approximately 0.8:1 Sodium: 55 mg Caffeine option: Caf 100 version adds 100 mg caffeine Best for: athletes with sensitive stomachs; races over 90 minutes Not ideal for: budget-conscious athletes (cost is roughly $3.50 to $4.50 per gel)

Maurten Gel 100 on Amazon (affiliate link)

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2. SiS Beta Fuel (best for high carb intake)

Science in Sport Beta Fuel uses a 1:0.8 maltodextrin-to-fructose ratio, which is closer to parity than the older 2:1 recommendation and allows higher total absorption per hour. At 40 g of carbohydrate per sachet, it is the highest-density isotonic gel on the market. Isotonic means it does not require additional water to absorb, which simplifies race-day execution.

Carbs per sachet: 40 g Glucose:fructose ratio: 1:0.8 (higher fructose than most) Sodium: 55 mg Caffeine option: Beta Fuel with Caffeine adds 75 mg Best for: athletes targeting 80 to 90 g carbs per hour; longer events Not ideal for: athletes new to high-carb fueling (gut training required)

SiS Beta Fuel on Amazon (affiliate link)

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3. GU Energy Gel (best value)

GU uses a maltodextrin and fructose blend (roughly 2:1) in a 22 g carbohydrate sachet. It is widely available, inexpensive at around $1.50 to $2.00 per gel, and comes in more flavor options than any other brand. The sodium content at 60 mg per sachet also helps with electrolyte replacement.

Carbs per sachet: 22 g Glucose:fructose ratio: approximately 2:1 Sodium: 60 mg Caffeine option: multiple options from 20 mg to 40 mg Best for: athletes on a budget; well-stocked races where GU is provided Not ideal for: athletes needing 40 g per sachet to hit high carb targets

GU Energy Gel on Amazon (affiliate link)

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4. Precision Fuel PF30 (best isotonic option)

Precision Fuel and Hydration's PF30 gel is isotonic, meaning it is formulated to be absorbed without additional water. Each sachet provides 30 g of carbohydrate from a 2:1 maltodextrin-to-fructose ratio. The brand is well-regarded for rigorous lab testing and consistent dosing.

Carbs per sachet: 30 g Glucose:fructose ratio: 2:1 Sodium: 30 mg Caffeine option: PF30 Caffeine version adds 100 mg Best for: athletes who want an isotonic option without the Maurten price Not ideal for: athletes needing full electrolyte replacement from their gel

Precision Fuel PF30 on Amazon (affiliate link)

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5. Clif Shot Turbo (best caffeine dose per gel)

Clif Shot Turbo delivers 100 mg of caffeine per 25 g sachet, the highest caffeine-to-carb ratio of any mainstream gel. For athletes who want to time their caffeine hit mid-race without carrying extra caffeine products, it is a practical option. The carbohydrate blend uses both maltodextrin and fructose.

Carbs per sachet: 25 g Sodium: 95 mg Caffeine: 100 mg Best for: mid-race caffeine timing in a single product; athletes with high caffeine tolerance Not ideal for: early-race fueling or athletes sensitive to caffeine

Clif Shot Turbo on Amazon (affiliate link)

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How many gels per marathon?

Use the carb calculator to get an exact target. As a rough guide: a 4-hour marathon runner targeting 60 g of carbs per hour needs roughly 10 GU gels or 6 Maurten Gel 100 sachets for the full race. At 90 g per hour using a dual-transport gel, the same runner needs about 9 SiS Beta Fuel sachets. Most marathons provide one gel brand on course at miles 13 and 20, so plan your own supply for the remaining intake.

Should you use gels or real food?

For standard marathon distances (sub 5 hours), gels are more practical than real food because they absorb faster, require no chewing, and are easier to carry. Ultra-distance athletes or those running over 5 hours often do better with solid food after hour 3, when gut fatigue from gels becomes a bigger factor. The DIY sports drink tool is an option for athletes who want carbohydrates in liquid form instead.

Frequently asked questions

How many gels should I take in a marathon?

For a 3 to 4 hour marathon runner targeting 60 g of carbohydrate per hour, you need roughly 7 to 10 standard gels (22 to 25 g each) for the full race. Start fueling at mile 4 to 5 rather than waiting until you feel tired. If you are using higher-density gels like SiS Beta Fuel (40 g per sachet), you need fewer sachets but must ensure your gut is trained for the higher fructose load before race day. Practice your exact gel brand and timing in long training runs.

When should I take my first gel in a marathon?

Take your first gel between miles 4 and 6, which is roughly 30 to 45 minutes into the race. Starting earlier tops off muscle glycogen before depletion begins and avoids a later scramble to catch up. Waiting until you feel energy dropping is too late, as it takes 15 to 30 minutes for carbohydrates to reach working muscles. For races over 3 hours, aim to start fueling within the first 30 minutes.

Do marathon gels go bad?

Marathon gels have a shelf life of 12 to 24 months, printed on the packaging. Storing them above 30 degrees Celsius (86 degrees Fahrenheit) for extended periods can degrade the texture and flavor but does not make them unsafe. Gels carried in a jersey pocket or race kit for a single race day are fine regardless of ambient temperature. Do not use gels that have been frozen and thawed multiple times, as the texture becomes uneven.

Can I make my own marathon gels?

You can approximate a gel by mixing maltodextrin and fructose powder in a 2:1 ratio with a small amount of water until you reach a thick consistency. At 30 g of total carbohydrate per serving (20 g maltodextrin, 10 g fructose), the cost is under $0.20 per serving compared to $1.50 to $4.50 for commercial gels. Add a pinch of salt for sodium. The downside is packaging: you need reusable flask bottles to carry the mixture, which adds complexity on race day.