During-effort fuel · electrolyte · reviewed 28 Aug 2026
High5 Zero Electrolyte Tablets 41
56 mg of magnesium a tablet — more than any other tablet in this set, just short of LMNT's 60 mg stick dose — alongside 250 mg of sodium, the same figure as 4Endurance's tablet, at zero calories and zero sugar.
Score breakdown
The overall score is the average of what's below, each measured against every other electrolyte we've reviewed.
41
Mixed
Sodium dose ?Sodium per serving, on a scale topping out at 1000 mg — a single dose covering the top of what's typically lost to sweat in an hour.25
Value (cost/1000mg Na) ?What it costs to get 1000 mg of sodium from this product. Not physiological -- a market-based scale from $3.00 (0) to $1.00 (100).42
Potassium ?Potassium per serving, on a scale topping out at 200 mg — roughly the upper end of typical hourly sweat loss.35
Calcium ?Calcium per serving. Weaker grounding than sodium/potassium -- sweat calcium loss is minor and not really a primary target during exercise; the 100 mg ceiling is this catalog's practical high end, not a physiological one.9
Magnesium ?Magnesium per serving, on a scale topping out at 60 mg, roughly matching cited hourly sweat-loss ranges.93
Cost per 1000mg sodium
$2.16/1000mg
Sodium per tablet
250mg
Comparison
6 of 11 electrolytes heldPrices per single sachet at the cheapest box size we track. Best in green, worst in red, across the gels shown.
| Measure | High5 High5 Zero Electrolyte Tablets | LMNT LMNT Citrus Salt | Nuun Nuun Sport | Precision Fuel & Hydration Precision Fuel & Hydration PH 1000 | Science in Sport SiS GO Hydro | 4Endurance 4Endurance Electrolytes |
|---|---|---|---|---|---|---|
| SodiumThe main electrolyte lost in sweat, and the biggest single driver of cramping and hyponatremia risk. | 250 mg | 1000 mg | 300 mg | 500 mg | 345 mg | 250 mg |
| PotassiumWorks alongside sodium in muscle and nerve function. | 70 mg | 200 mg | 150 mg | 130 mg | 65 mg | 70 mg |
| CalciumInvolved in muscle contraction; lost in far smaller amounts than sodium. | 9 mg | 0 mg | 13 mg | 20 mg | 102 mg | 10 mg |
| MagnesiumSupports muscle and nerve function; some evidence it blunts cramping. | 56 mg | 60 mg | 25 mg | 10 mg | 8.1 mg | 50 mg |
| CarbohydrateMinimal by design. This is a hydration product, not a fuel source. | 0 g | 0 g | 4 g | 3 g | 0.9 g | 0 g |
| Price per tabletWhat one tablet costs. | $0.54 | $1.50 | $0.75 | $1.20 | $0.75 | $0.27 |
| Cost per 1000mg sodiumThe only price that compares across different sodium concentrations. | $2.16 | $1.50 | $2.50 | $2.40 | $2.17 | $1.08 |
Verdict
what it does · what it costsWhat it does well
- 56 mg of magnesium, the highest of any tablet here (only LMNT's stick, at 60 mg, carries more).
- Zero calories and zero carbohydrate, with 28 mg of vitamin C included.
- Nine flavours in the range, more variety than any other electrolyte product here.
What it costs you
- 250 mg of sodium is well below LMNT's 1000 mg or Precision's 500 mg.
- Green tea extract is declared at 1 mg but not broken out as a caffeine dose, so the actual caffeine content can't be read off this label.
- Not sold through US retailers; pricing here is converted from GBP and availability will vary.
Where to buy
Prices and links as last checked.
Who this is for
the numbers, appliedThe field tells you what it is. This is who should act on it.
Worth the money if
- You want the highest magnesium dose of any tablet here without LMNT's full 1000 mg of sodium.
- You want a zero-calorie, zero-sugar tablet with vitamin C built in.
Look elsewhere if
- You're comparison-shopping strictly in US dollars; this line is priced in GBP with no confirmed US listing.
- You need a large single-tablet sodium dose; 250 mg is modest next to LMNT or Precision.