How many CLIF BLOKS per run and how to use them effectively

November 12, 2025 •

4 min read

According to Clif Bar's official recommendations, consuming 3 to 6 CLIF BLOKS per hour of activity is the standard guideline for performance athletes. Knowing how many CLIF BLOKS per run you need, however, depends on factors like distance, intensity, and personal tolerance.

Quick Summary

The number of CLIF BLOKS consumed during a run varies based on duration and individual needs, typically ranging from 3 to 6 chews per hour during endurance activities. Effective use involves proper timing, hydration, and testing different flavors or caffeine levels during training runs to avoid stomach issues on race day.

Key Points

Standard Intake: For endurance runs over an hour, aim for 3 to 6 CLIF BLOKS per hour, consuming them with water.
Start Smart: A quick energy boost can be achieved by taking half a packet (3 bloks) about 15 minutes before your activity begins.
Marathon Strategy: Many marathoners find success by consuming 3 bloks every 20-30 minutes, totaling about one full packet per hour.
Hydrate to Absorb: Always drink water alongside your CLIF BLOKS to assist digestion and the efficient absorption of carbohydrates and electrolytes.
Practice Makes Perfect: Test your specific CLIF BLOKS fueling strategy during training runs to ensure it works well for your stomach and energy needs on race day.
Leverage Caffeine: Consider using caffeinated CLIF BLOKS later in a long run for a mental pick-me-up, but start with non-caffeinated flavors.
Beat Palate Fatigue: On very long runs, mix up your fuel sources by alternating CLIF BLOKS with gels or other foods to keep things interesting and prevent flavor burnout.

The Science Behind CLIF BLOKS Fueling

CLIF BLOKS are designed as an easily digestible source of carbohydrates, providing a semi-solid alternative to energy gels and bars for endurance athletes. The key to their effectiveness lies in the blend of simple and complex sugars, like tapioca syrup and maltodextrin, which provides a steady release of energy without the dramatic spike and crash associated with pure sugar. For any run lasting over an hour, replenishing your glycogen stores is crucial to avoid 'bonking' or hitting the wall. Each standard CLIF BLOK contains about 33 calories and a balanced mix of sugars and electrolytes to support muscle function and hydration.

How Many BLOKS for Different Run Distances?

Your fueling strategy should adapt to the length and intensity of your run. While the 3-6 bloks per hour guideline is a solid starting point, here's how to customize it for various distances:

For a Half Marathon (1.5 to 2.5 hours):

Before the race: Take half a packet (3 bloks) approximately 15 minutes before starting to top off glycogen stores.
During the race: Aim for 3-6 bloks per hour, starting around the 45-60 minute mark. For a 2-hour run, this would translate to about one to two packets total, depending on your pace and energy needs.
Hydration: Always consume water with your bloks to aid absorption and prevent stomach upset.

For a Marathon (3+ hours):

Before the race: A half packet can serve as a pre-race boost.
During the race: The goal is to ingest 30-60 grams of carbohydrates per hour. Since a full pack provides 48g of carbs, consuming one packet per hour is a sound strategy, supplemented by other nutrition. Many marathoners find it effective to consume 3 bloks every 20-30 minutes, staggering the intake for consistent energy.
Testing is vital: Use your long training runs to fine-tune your exact dosage. Some runners prefer a combination of gels and chews to vary texture and carb sources during a long event.

For Ultra Events:

Ultra-endurance events require a more complex nutritional strategy, often mixing chews with other calorie sources. Some runners consume more than the standard 1-2 packets per hour, sometimes ignoring the daily dose recommendation, but only after rigorous training confirms tolerance.
The prolonged nature of these runs can lead to palate fatigue, making the variety of flavors and easy-to-chew texture of bloks an advantage.
Experimentation during long training sessions is non-negotiable to determine your individual carbohydrate capacity.

Comparison Table: CLIF BLOKS vs. Other Fuel Options


Feature	CLIF BLOKS	Energy Gels	Energy Bars	Real Food (e.g., Banana)
Texture	Semi-solid, chewy cube	Gelatinous, liquid	Solid, chewable	Solid, natural
Ease of Consumption	Easy, chew one at a time from Fastpak	Squeezable, quick; can be messy	Requires more chewing, can be heavy	Messy, variable texture
Carbohydrate Source	Balanced simple/complex sugars	Primarily maltodextrin (gels) or a blend	Varies; often grains, nuts, and sugars	Simple sugars, some fiber
Energy Release	Steady, sustained energy	Rapid absorption, quicker boost	Slower release, more satisfying	Mix of fast and slower energy
Electrolyte Content	Added sodium and potassium	Varies by brand; some contain electrolytes	Minimal to none	Minimal
Palatability	Variety of fruity flavors	Often strong, sometimes cloying taste	Varies widely by ingredients	Natural, familiar flavor

Practical Tips for Using CLIF BLOKS on Your Run

Practice on Training Runs: Never try a new fueling strategy on race day. Use your long training runs to test your consumption rate, water intake, and stomach tolerance for CLIF BLOKS.
Stay Hydrated: The electrolytes in CLIF BLOKS work best with proper hydration. Always follow consumption with a sip of water to aid digestion and absorption.
Use the Fastpak Design: The convenient Fastpak allows you to squeeze out one blok at a time without handling the entire packet, reducing mess and making on-the-go fueling easier.
Consider Flavor and Caffeine: CLIF BLOKS come in caffeinated and non-caffeinated options. Use caffeinated flavors strategically for a mental and physical boost late in a long race, and non-caffeinated ones for consistent energy earlier on.
Listen to Your Body: Your fueling needs are unique and will vary with intensity and weather. Pay attention to how your body responds and adjust your intake accordingly to avoid gastrointestinal issues.

Conclusion

For endurance runners, knowing how many CLIF BLOKS per run to consume is a personalized decision built on general guidelines and extensive training practice. The standard recommendation of 3 to 6 bloks per hour provides a reliable framework for maintaining energy, but your specific needs will depend on the duration and intensity of your activity. By practicing your fueling strategy, combining bloks with water, and listening to your body's feedback, you can effectively use CLIF BLOKS to power through your next race or long run with sustained energy and confidence.

Key Takeaways

Recommended Intake: Consume 3 to 6 CLIF BLOKS per hour during endurance activities lasting more than 60 minutes.
Pre-Run Strategy: A half-packet of CLIF BLOKS taken 15 minutes before a run can boost your blood sugar and energy levels.
Marathon Fuelling: For a marathon, aim to consume 30-60 grams of carbs hourly, which may equate to one packet (6 bloks) per hour, adjusting based on other calorie intake.
Must Add Water: Always consume CLIF BLOKS with water to ensure proper digestion and hydration.
Test and Refine: Practice your fueling strategy during training to find the optimal intake frequency and amount that works for your body.
Use Caffeine Wisely: Utilize caffeinated flavors strategically for late-race boosts, while relying on non-caffeinated options for consistent energy.
Mix Your Fuel Sources: Alternate CLIF BLOKS with gels or other real foods during ultra-endurance events to prevent palate fatigue and potential GI issues.

Frequently Asked Questions

You should aim to consume 3 to 6 CLIF BLOKS per hour during any activity lasting more than 60 minutes. Each blok contains approximately 33 calories and a half-packet (3 bloks) provides 24 grams of carbohydrates.

For optimal fueling, start consuming CLIF BLOKS after the first 45-60 minutes of your run. Some athletes also consume half a packet 15 minutes before starting their activity for an initial energy boost.

Yes, you should always follow the consumption of CLIF BLOKS with a drink of water. This aids in the proper absorption of the carbohydrates and electrolytes, helping to prevent any potential stomach upset.

CLIF BLOKS are a semi-solid, easy-to-chew alternative to energy gels, with many runners appreciating their more food-like texture and the ability to control intake one blok at a time. The 'best' option depends on individual preference and tolerance.

For a marathon, consider a strategy of taking 3 bloks every 20-30 minutes, combined with proper hydration. Test this timing during long training runs to ensure it works for your system on race day.

Caffeinated CLIF BLOKS are best used strategically, especially during the later stages of a long race for a mental and physical boost. It's wise to limit their consumption to avoid relying on caffeine and to prevent potential side effects like jitteriness.

The Fastpak is the unique packaging for CLIF BLOKS that allows runners to easily access individual chews on the go. It enables you to squeeze one blok up at a time, minimizing mess and distraction during a run.

Key ingredients include organic tapioca syrup, organic dried cane syrup, and organic maltodextrin. These provide a balanced mix of carbohydrates, while added electrolytes like sodium and potassium aid in hydration and muscle function.

For a marathon, you would likely need 3-4 packs of CLIF BLOKS to maintain a consistent hourly carb intake, depending on your individual needs and whether you use other nutrition sources. Always practice with this amount during training.