Salt Tablets for Runners: Who Needs Them, How Many, and When They Do Nothing
Salt tablets help a specific kind of runner in a specific kind of run and do nothing for everyone else. Here is how to tell which you are, how much sodium you actually lose, how many tablets that means per hour, and how to take them without upsetting your stomach.
Quick answer
Salt tablets are worth taking if you run for more than about 2 hours, especially in heat, and lose a lot of sodium: heavy sweaters and salty sweaters who finish with white streaks on their kit. A typical salt capsule contains 200 to 250 mg of sodium, and most runners in that group need 300 to 600 mg of sodium per hour, which is one to three capsules per hour taken with 150 to 250 ml of water. Runners doing races under 90 minutes, or easy runs in cool weather, do not need them, and salt tablets do not reliably prevent muscle cramps, which are mostly caused by fatigue rather than salt loss. They also do not replace drinking; overdrinking plain water is a bigger danger than under-salting.
Every start line has a runner swallowing a handful of salt tablets because a friend told them it stops cramps, and another runner who has never touched one and finishes covered in white streaks wondering why they faded in the heat. Both are guessing. Sodium is the one part of fueling where the right answer varies tenfold between runners, and the tablets only help if you are the kind of runner they are made for.
This guide tells you whether you are that runner, how much sodium you actually lose, what that means in tablets per hour, when tablets do nothing, and how to take them without turning a hydration plan into a stomach problem.
The Short Answer
- Runs and races under 90 minutes: you do not need salt tablets. A salted meal before is enough.
- Runs over 2 hours in cool weather: most runners are fine with the sodium in gels and a drink mix. Salty sweaters benefit from adding 300 to 500 mg per hour.
- Runs over 2 hours in heat, or any run over 4 hours: almost everyone benefits from a deliberate sodium plan, typically 500 to 800 mg per hour, and salt tablets are the easiest way to hit it.
- A standard capsule is 200 to 250 mg of sodium, so the typical dose is one to three per hour, each with a good drink of water.
- Salt tablets do not reliably stop cramps, do not replace drinking, and do not protect you if you overdrink plain water.
What Is Actually in a Salt Tablet
The word covers several different products, and the sodium per unit varies a lot. Salt is about 40 percent sodium by weight, so a tablet containing 1 g of salt gives you around 390 mg of sodium, which is the number that matters. Always read the sodium line, not the salt line.
| Product | Typical sodium per unit | Notes |
|---|---|---|
| Salt capsule (swallowed) | 200 to 250 mg | Most common format; usually also potassium, magnesium, calcium in small amounts. Some brands offer 300 to 500 mg versions. |
| Buffered salt tablet (chewed or swallowed) | 200 to 400 mg | Coated to be gentler on the stomach |
| Dissolvable electrolyte tablet (in a bottle) | 300 to 500 mg | Not a salt tablet as such; you get the sodium only if you drink the whole bottle |
| High-sodium drink mix sachet | 500 to 1,500 mg | The strongest single dose available; designed for salty sweaters and heat |
| Energy gel | 20 to 200 mg | Varies wildly by brand; check the label, some are almost sodium-free |
| Sports chews, per serving | 40 to 100 mg | Minor contribution |
| Salted pretzels, 30 g | 350 to 450 mg | Real-food option for ultras; needs water to get down |
| Table salt, 1/4 teaspoon | About 575 mg | The cheapest salt tablet in existence, for a homemade drink |
Do You Need Them? Three Questions
| Question | If yes | If no |
|---|---|---|
| Will you be running for more than 2 hours? | Sodium replacement is worth planning | Skip tablets. Salt your pre-run meal and move on. |
| Will it be hot, humid, or are you not yet heat-adapted? | Losses go up sharply; add 200 to 300 mg per hour to your baseline | Baseline dose is enough |
| Are you a salty sweater? White streaks on kit, stinging eyes, craving salt after runs | You are likely above 1,000 mg/L and need the upper end of every range | You are likely near or below average and the lower end will do |
Two yeses and you should have a plan. Three yeses and you should have tested it in training well before race day. No yeses and the money is better spent on gels.
How Much Sodium Runners Actually Lose
Sodium loss is sweat rate multiplied by sweat sodium concentration, and both vary enormously. Sweat rates in runners range from about 0.5 to over 2 litres per hour depending on pace, heat, and body size. Sweat sodium ranges from roughly 200 to 2,000 mg per litre, with a typical value around 900 to 1,000 mg/L. Put those together and the hourly loss can be anything from 100 mg to more than 3,000 mg.
| Sweat rate | Low sodium sweat (500 mg/L) | Average sweat (1,000 mg/L) | Salty sweat (1,500 mg/L) |
|---|---|---|---|
| 0.6 L/h (cool, easy) | 300 mg/h | 600 mg/h | 900 mg/h |
| 1.0 L/h (mild, steady) | 500 mg/h | 1,000 mg/h | 1,500 mg/h |
| 1.5 L/h (warm, hard) | 750 mg/h | 1,500 mg/h | 2,250 mg/h |
| 2.0 L/h (hot, racing) | 1,000 mg/h | 2,000 mg/h | 3,000 mg/h |
You do not need to replace all of it. The body tolerates a moderate sodium deficit over a few hours without any loss of performance, and it corrects the balance at the next meal. The practical target for long efforts is to replace roughly a third to two thirds of what you lose, which keeps blood sodium stable, helps you retain the fluid you drink, and avoids the stomach load of trying to match losses gram for gram. You can measure your own sweat rate at home with a scale and a towel; the calculator below does the arithmetic.
Free calculator
Calculate your sweat rate
Use measurements from one representative workout. The formula accounts for drinks and any urine passed during the test.
A sweat-rate estimate is a planning input, not an instruction to replace every milliliter while moving. Avoid drinking enough to gain weight during exercise, and seek qualified medical advice for a history of hyponatremia, kidney or heart conditions, or heat illness.
How Many Salt Tablets Per Hour
Convert the target to tablets using the sodium per capsule on your label. The table assumes a standard 215 to 250 mg capsule and already accounts for the sodium you will get from gels and a typical sports drink, roughly 100 to 300 mg per hour.
| Runner and conditions | Sodium target | Salt capsules per hour | Also |
|---|---|---|---|
| Average sweater, cool weather, 2 to 3 hours | 300 to 500 mg/h | 0 to 1 | Gels and drink mix usually cover it |
| Average sweater, warm weather, 2 to 4 hours | 500 to 700 mg/h | 1 to 2 | Drink to thirst; add sodium to the bottle |
| Salty sweater, cool weather, 2 to 4 hours | 600 to 800 mg/h | 2 | Pre-load with a salted meal 2 to 3 hours before |
| Salty sweater, hot weather, any distance over 2 hours | 800 to 1,200 mg/h | 3 to 4, or switch to a high-sodium drink mix | Pre-load 500 mg with 500 ml of fluid 90 minutes before |
| Ultra, 6 hours or more, mixed conditions | 500 to 800 mg/h averaged | 1 to 3, alternating with salty real food | Reassess every 2 hours; cravings and puffy fingers are signals |
The ceiling that matters is the stomach, not the kidneys. Above roughly 1,000 to 1,200 mg per hour, most runners get nauseous unless the sodium is spread through fluid rather than delivered in capsules. If you are in that territory, a high-sodium drink mix is the better tool.
When Salt Tablets Do Nothing
This is the section the tablet manufacturers skip. Salt tablets are sold on three promises, and only one of them holds up.
- Cramps. The popular story is that cramps come from salt loss. Controlled research does not support it: cramping runners in races have not been found to have lower blood sodium than non-crampers, and the strongest predictor of cramping is muscle fatigue from running faster or longer than you trained for. Salt may help a minority with genuinely high losses, but for most runners, cramps are a pacing and conditioning problem that a capsule cannot solve.
- Hydration. Sodium helps you retain the fluid you drink; it does not replace the fluid. A salt tablet with no water is worse than nothing, because it pulls fluid into the gut and makes you feel sick.
- Hyponatremia protection. Low blood sodium in runners is caused overwhelmingly by drinking more than you sweat, not by losing salt. Salt tablets reduce the risk only slightly and only if fluid intake is sensible. If you force down water at every aid station, no amount of salt will save you. Drink to thirst.
- Short events. In a 10K, a half marathon, or any run under 90 minutes, sodium losses are small, the body has a large reserve, and a normal diet with a salted pre-race meal covers everything. Tablets here are pure placebo.
How to Take Them Without Wrecking Your Stomach
- Every capsule goes down with 150 to 250 ml of water. Never dry, never with a mouthful.
- Start early. Take the first one 30 to 60 minutes in, before losses have piled up, and then on a schedule. Waiting until you feel bad means you are already behind.
- Spread the dose. One capsule every 30 minutes beats three every 90 minutes.
- Count everything. Add up the sodium in your gels and your drink mix before deciding how many capsules you need; stacking a salted drink with capsules is the usual cause of tablet-related nausea.
- Practise in training on runs that mimic race conditions. If your race is hot and long, at least three long runs should use the full plan.
- Pre-load, do not front-load. A salted meal 2 to 3 hours before and, for hot races, about 500 mg of sodium with 500 ml of fluid 90 minutes before the start. Do not swallow four capsules on the start line.
- If you get nauseous, stop the capsules for an hour, sip plain water and a little carbohydrate, and resume at a lower rate.
Salt Tablets vs Electrolyte Drinks vs Salty Food
| Option | Best for | Drawback |
|---|---|---|
| Salt capsules | Precise dosing when you are drinking plain water from aid stations, or want sodium separate from carbohydrate | Easy to overdo; useless without water; some runners find swallowing capsules while running hard |
| High-sodium drink mix | Salty sweaters in heat; carrying your own bottle; combining fluid and sodium in one step | Ties sodium intake to fluid intake; limited by how much you carry |
| Standard sports drink | Races under 3 hours in mild weather; sodium arrives with carbohydrate and fluid | Usually only 200 to 500 mg per litre, too little for salty sweaters or heat |
| Salty gels and chews | Topping up during marathons without extra products | Sodium content is unpredictable between brands; rarely enough on its own |
| Salty real food | Ultras and long training runs; breaks the sweetness fatigue | Slow to eat, needs water, hard to dose accurately |
A Sodium Plan by Race Distance
| Race | Cool conditions | Hot conditions |
|---|---|---|
| Half marathon | Salted breakfast; sports drink on course; no tablets | Salted breakfast plus 500 mg pre-load; one capsule at the hour mark for salty sweaters |
| Marathon | Gels with sodium plus course sports drink, about 300 to 500 mg/h; salty sweaters add one capsule per hour | 500 mg pre-load; 1 to 3 capsules per hour or a high-sodium mix in a carried bottle; drink to thirst |
| 50K to 50 miles | 500 to 700 mg/h, mixing capsules and salty food at aid stations | 700 to 1,000 mg/h; alternate capsules and drink mix; reassess every 2 hours |
| 100K and beyond | 500 to 800 mg/h averaged; watch for salt cravings and puffy fingers as signals | Same, with the top of the range through the hottest hours and a dedicated bottle for sodium |
Mavr stores your sweat rate and sweat sodium, sets a sodium target for every run and race from the forecast and duration, and tells you how to hit it with the tablets, drinks, and gels you already use.
Frequently Asked Questions
Do runners need salt tablets?
Only some. If you run for more than about 2 hours, particularly in heat, and you sweat heavily or lose a lot of salt, tablets are a convenient way to replace 300 to 800 mg of sodium per hour. Runners doing events under 90 minutes, or easy runs in cool conditions, get all the sodium they need from food and do not benefit.
How many salt tablets should I take per hour when running?
Most capsules contain 200 to 250 mg of sodium. Average sweaters in warm weather need one to two per hour; salty sweaters in heat need three to four or should switch to a high-sodium drink mix. Subtract the sodium already in your gels and drink, and take every capsule with 150 to 250 ml of water.
Do salt tablets prevent cramps when running?
Not reliably. Studies of cramping runners have not found lower blood sodium than in runners who did not cramp, and the strongest predictor of cramping is fatigue from running harder or longer than you trained for. Salt may help a minority with very high sweat losses, but pacing and conditioning matter far more.
How much sodium do I lose per hour running?
Sweat rate multiplied by sweat sodium concentration. A typical runner sweating 1 litre per hour at 1,000 mg per litre loses about 1,000 mg an hour; a salty sweater in heat can lose 2,000 to 3,000 mg. Replace roughly a third to two thirds of that during runs longer than 2 hours.
Should I take salt tablets before a marathon?
A salted breakfast 3 hours before covers cool conditions. For a hot marathon, add about 500 mg of sodium with 500 ml of fluid around 90 minutes before the start. Do not swallow several capsules on the start line; that just causes nausea in the first 5K.
Can you take too many salt tablets?
Yes. Above roughly 1,000 to 1,200 mg per hour in capsule form, most runners get nauseous and bloated, and taking capsules without water pulls fluid into the gut. Sodium overload is rare because the kidneys handle it, but the stomach sets the limit long before then.
Sources
Sources and official references
- 1.Sweating Rate and Sweat Sodium Concentration in Athletes: A Review of Methodology and Intra/Interindividual VariabilitySports Medicine (Baker, 2017) · The tenfold range in sweat sodium between athletes and the factors that move it
- 2.Normative Data for Regional Sweat Sodium Concentration and Whole-Body Sweating Rate in AthletesJournal of Sports Sciences (Baker et al., 2016) · Typical sweat rates and sodium concentrations across sports and conditions
- 3.Statement of the Third International Exercise-Associated Hyponatremia Consensus Development ConferenceClinical Journal of Sport Medicine (Hew-Butler et al., 2015) · Overdrinking, not sodium loss, as the main cause of low blood sodium in runners
- 4.Sodium Supplementation and Exercise-Associated Hyponatremia during Prolonged ExerciseMedicine and Science in Sports and Exercise (Hoffman and Stuempfle, 2015) · Sodium supplementation in a 161 km ultra did not prevent hyponatremia when fluid intake was excessive
- 5.Cause of Exercise Associated Muscle Cramps (EAMC): Altered Neuromuscular Control, Dehydration or Electrolyte Depletion?British Journal of Sports Medicine (Schwellnus, 2009) · The evidence that cramps are primarily neuromuscular rather than electrolyte-driven
- 6.Sports Dietitians Australia Position Statement: Nutrition for Exercise in Hot EnvironmentsInternational Journal of Sport Nutrition and Exercise Metabolism (McCubbin et al., 2020) · Sodium and fluid recommendations for training and racing in the heat
- 7.Exercise and Fluid Replacement: ACSM Position StandMedicine and Science in Sports and Exercise (Sawka et al., 2007) · Sodium replacement guidance for exercise lasting longer than 2 hours
Prompt ideas for AI assistants
- “How many salt tablets should I take during a marathon?”
- “How much sodium do I lose per hour running in the heat?”
- “Will salt tablets stop my calf cramps in the last 10K?”
Mavr turns your sweat test into a sodium target for each run and race and tells you how to hit it with the tablets, drinks, and gels you already carry.
Written by
Mavr Sports Nutrition Team
The Mavr sports-nutrition team translates peer-reviewed endurance research (Jeukendrup, Burke, the ISSN) into daily fueling for runners and triathletes.