LYTEWORK HYDRATION TOOLS

Ironman Hydration
Calculator

Plan your Ironman or 70.3 hydration strategy. Calculate fluid intake, sodium requirements, and electrolyte capsule dosing based on sweat rate, sodium loss, race duration, and environmental conditions.

IRONMAN hydration is one of the biggest variables in long-course racing.

Fluid losses, sodium losses, race duration, and conditions all affect how much you may need to replace.

Because sweat rate and sweat sodium concentration vary widely between athletes, hydration plans should be individualised rather than guessed.

Use the Lytework IRONMAN Hydration Calculator below to estimate sodium needs, capsule count, fluid targets, and a practical race-day protocol.

■  Lytework Race Protocol

IRONMAN Hydration Calculator

Estimate sodium loss, capsule needs, and a practical race-day hydration plan for Ironman and 70.3 racing.

■  Race details
kg
10h 00m
3h 30m17h 00m
■  Sweat profile

Salt marks on kit, stingy eyes, or salty lips? Choose High. Light or no visible salt? Choose Low.

■  Race-day environment
22°C
5°42°
50%
20%95%

Hot and humid conditions can increase sweat rate by up to 50%. Protocol adjusts automatically.

■  Sodium from drinks

If you plan to drink electrolyte drinks during the race, enter them here. The calculator will subtract this sodium from your capsule target.

mg/L
This drink provides 500 mg sodium/hr

Enter your race details and hit Build my race plan to see your personalised hydration protocol.

■  Total sodium target
■  Swim / Bike / Run splits
■  Capsule schedule
■  Race-day protocol steps
■  Packing guide
■  Fluid strategy

How it works

How to use the calculator

  1. Set your race duration

    Use your expected finish time to estimate discipline splits and overall hydration demand.

    Full Ironman or 70.3

  2. Choose your sweat profile

    Select the sweat rate and sodium level that best match your training experience, conditions, and visible salt losses.

    Salt on kit = choose High

  3. Build your race plan

    The calculator estimates total sodium target, capsule count, bike and run timing, fluid targets, and a practical packing guide.

    Save it for race week

Reference ranges

Example IRONMAN Hydration Ranges

These are broad starting ranges only. Fluid and sodium needs still vary based on sweat rate, sodium concentration, conditions, pacing, and execution.

Athlete profile Fluid intake Sodium intake Practical cue
Low sweat rateCooler conditions / smaller fluid losses 400–600 mL/hr 300–500 mg/hr Steady small drinks. Avoid overdrinking early.
Moderate sweat rateTypical long-course starting point 600–900 mL/hr 500–900 mg/hr Build an early bike rhythm and stay consistent.
High sweat rateWarmer racing / larger fluid losses 900–1200 mL/hr 900–1500+ mg/hr Prioritise early intake and plan bottles carefully.

Lytework view:Sweat rate helps guide fluid intake, but sodium needs can still vary widely between athletes. Use the calculator to personalise your plan.

Race Day Hydration Strategy

Effective IRONMAN hydration usually comes down to consistency, not large infrequent drinks.

Practical principles include:

  • drinking small amounts regularly on the bike and run
  • starting sodium and fluid intake early rather than chasing later
  • adjusting for heat, humidity, and pacing
  • separating fluid and sodium intake so both can be controlled independently
  • practising your approach in long sessions before race day
IRONMAN FAQ
How much should you drink during an Ironman?

Fluid intake during an Ironman varies widely depending on sweat rate, conditions, and athlete size. Many athletes consume between 500 ml and 1000 ml of fluid per hour, although some may need more in hot conditions.

How much sodium should you take during an Ironman?

Sodium needs can vary dramatically between athletes. Some athletes may require only a few hundred milligrams per hour, while heavy sodium sweaters may require more than 1000 mg per hour.

Should you drink to thirst in an Ironman?

Many athletes combine thirst cues with a structured hydration plan. Having a general target for fluid intake can help avoid large hydration deficits during very long races.

Why do athletes cramp in Ironman races?

Cramping during endurance events can have many causes including fatigue, pacing, hydration status, and sodium balance.

Managing pacing and maintaining a consistent hydration strategy may help reduce risk.

Tools

Build a more precise hydration system

Race fueling works best when carbohydrate, fluid, and sodium are controlled with intention. Use the Lytework calculators to refine your full endurance hydration and fueling strategy.

Build your sodium protocol Build Hydration Plan Calculate Sweat Rate Calculate Race Fueling