Baking Soda and Lemon Water: Ratio, Fizz and Sodium

How much baking soda goes in lemon water, in US and metric measures, why it fizzes, and how many milligrams of sodium each spoonful adds to the glass.

One popular version of this recipe pairs 1 teaspoon of juice with 1/2 teaspoon of soda. By our calculation that is too little acid to use up the soda. This page fixes the ratio, shows the sodium in milligrams, and keeps the claims modest. If you came here for weight loss, start with our baking soda recipe for weight loss, which covers what the research does and does not show. Nothing here promises weight loss or any other health effect.

The Food Science / Lab Kitchen Note

Baking soda is sodium bicarbonate, a base. Lemon juice is sour because of citric acid. When they meet, the acid takes up the bicarbonate and releases carbon dioxide gas, which is the fizz. What stays in the glass is sodium citrate, water and some dissolved gas. So lemon juice and baking soda make a mild salt solution with bubbles.

The numbers below are a calculation from published figures, not a result from a study. Penniston and colleagues measured fresh lemon juice at 48.0 g/L of citric acid, or 1.44 g per ounce (see the study below). Citric acid (192.12 g/mol) can neutralize up to three moles of sodium bicarbonate (84.007 g/mol each, 252.02 g in all), per PubChem. One gram of citric acid therefore neutralizes about 1.31 g of bicarbonate.

Half a lemon gives about 24 g of juice, roughly 1.1 g of citric acid, enough for about 1.5 g of bicarbonate. That covers 1/4 teaspoon (1.15 g) on paper. A 1/2 teaspoon (2.3 g) needs a whole lemon. Lemons vary, so treat this as a likely outcome, not a guarantee.

The sodium does not go anywhere. Neutralizing turns bicarbonate into sodium citrate, which still counts toward your day. For the same reason, adding more juice does not lower the sodium.

Temperature does not decide whether the soda dissolves. PubChem cites 9.3 g per 100 mL of water at 20 C, rising as water gets warmer. Our dose is about 0.5 g per 100 mL, far below that at any drinking temperature. Whether temperature changes fizz speed or taste, we found no source.

Sodium by spoonful

Using USDA's figure of 27,400 mg of sodium per 100 g of baking soda (FoodData Central), we calculate:

The FDA gives a Daily Value of less than 2,300 mg of sodium per day, and the Dietary Guidelines for Americans advise adults to stay under that. The sodium in the glass arrives on top of everything else you eat that day.

Lemon, lime, honey, ginger, warm or cold: what the data shows

This is a comparison of published data, not a taste test or a test of our own. Where a column says "no sourced data", we found nothing to compare. Each add-on is shown for one glass, next to the base glass above.

On these numbers lime and lemon are close, so either works at the same 24 g of juice; no taste data was sourced. For the 1/2 teaspoon (2.3 g) dose, use the juice of a whole lemon, about 48 g, so the acid still matches the soda and the sodium stays at about 630 mg.

What the sources say

The citric acid figures come from Penniston and colleagues, published in the Journal of Endourology in 2008. It is a laboratory analysis using ion chromatography, not a trial with people. Each fresh juice was measured on only two samples, lemon at 48.0 g/L and lime at 45.8 g/L, and the difference was not significant (P = 0.35). The bottled concentrates were single samples each, so the finding that bottled juice is weaker is a small-sample result. It tells us what is in the juice, not what the drink does in the body.

The usage directions come from MedlinePlus, a drug information page, not a study. It describes sodium bicarbonate as a treatment for heartburn and acid indigestion, with the powder dissolved in at least 4 oz (120 mL) of water, no more than 2 weeks unless a doctor says so, and not for children under 12 without a doctor. It lists no weight-loss use. Search suggestions mention constipation, reflux and upset stomach, but we found nothing in our sources that supports a claim for any of them.

Common mistakes

Too little juice. A teaspoon of juice cannot use up half a teaspoon of soda. Match the acid to the dose, or stay with 1/4 teaspoon and half a lemon.

Pouring soda onto the juice. The reaction is immediate and the foam can climb the glass. Dissolve the soda in water first.

Baking powder instead of baking soda. Baking powder is a different product and not a substitute. Check the label for sodium bicarbonate alone.

Heaping the spoon. Sodium rises in step with the dose, as the table shows. Level it every time.

Storage and safe use

Mix one glass and drink it. We found no sourced shelf life for the mixed drink, so we do not give one, and batching a pitcher is not covered by any source.

MedlinePlus says to take sodium bicarbonate at least 2 hours apart from other medicines. Because it adds sodium, people with high blood pressure, heart failure, kidney disease or a sodium-restricted diet are told to check first. If any of this applies to you, speak with your doctor or a dietitian before trying it.

Nutrition note

Values on the recipe card are estimates calculated from typical USDA FoodData Central values for raw lemon juice and baking soda, per glass. They are not measured. The glass comes to about 5 kcal, 1.7 g of carbohydrate and 0.6 g of sugars. It holds about 25 mg of potassium and about 315 mg of sodium, nearly all of the sodium from the baking soda. A glass made with lime juice is within a calorie or two of this.