Baking soda is technically abrasive, but it ranks as one of the softest abrasives you can use. With a Mohs hardness of 2.5, sodium bicarbonate is softer than a copper penny and far softer than most surfaces people worry about scratching. Whether it’s gentle enough depends entirely on what you’re using it on: tooth enamel, skin, a kitchen countertop, or an industrial surface.
How Baking Soda Compares to Other Abrasives
The Mohs hardness scale runs from 1 (talc) to 10 (diamond). Baking soda sits at 2.5, which places it below materials like calcium carbonate (3), glass (5.5), and quartz-based cleansers (7). For context, tooth enamel has a hardness around 5, meaning baking soda is roughly half as hard as the surface of your teeth. This is why it can polish without gouging the way harder abrasives do.
Commercial baking soda particles typically range from 50 to 100 microns, roughly the diameter of a fine human hair. That particle size, combined with the low hardness, makes it effective enough to scrub away surface grime while being too soft to scratch most hard surfaces like stainless steel, ceramic tile, or glass cooktops.
Baking Soda and Your Teeth
Toothpaste abrasiveness is measured on the Relative Dentin Abrasivity (RDA) scale, and plain baking soda scores a 7. The ADA’s recommended upper limit is 250, so baking soda is extraordinarily gentle by dental standards. Most commercial toothpastes fall somewhere between 30 and 100 on that scale, and whitening toothpastes often land between 100 and 200. Pure baking soda is less abrasive than virtually every toothpaste on the market.
That low RDA score means baking soda can clean teeth and remove surface stains without wearing down enamel or dentin over time. This is one reason many commercial toothpaste brands include it as an ingredient. If you brush with plain baking soda mixed with water, you’re using one of the least abrasive options available. The tradeoff is that it lacks fluoride and other active ingredients found in standard toothpastes, so it’s not a complete replacement for dental care on its own.
Baking Soda on Skin
Skin is a different story. Baking soda works as a physical exfoliant, similar to a salt or sugar scrub, when made into a paste or not fully dissolved in water. The fine particles can slough off dead skin cells, but the bigger concern isn’t the grit itself. It’s the pH.
Healthy skin is slightly acidic, typically around a pH of 4.5 to 5.5. This acid mantle forms a protective barrier that supports the natural bacteria keeping infection and acne at bay. Baking soda is alkaline, with a pH around 9, and applying it directly can neutralize that protective acidity. This strips the skin’s natural oil barrier, disrupts the surface microbiome, and can leave skin prone to dryness, irritation, and breakouts. Some people develop rashes, redness, or burning, particularly in sensitive areas like the armpits. Many people don’t realize they’re sensitive until they’ve already applied it.
So while the physical abrasion from baking soda particles is relatively mild on skin, the chemical disruption to your skin’s pH makes it a poor choice for regular facial or body use.
Baking Soda for Household Cleaning
As a household cleaner, baking soda hits a useful sweet spot. It’s abrasive enough to scrub away baked-on food, soap scum, and grease but soft enough to avoid scratching most kitchen and bathroom surfaces. You can safely use it on stainless steel sinks, ceramic tile, porcelain tubs, and most countertops.
There are a few surfaces where even this mild abrasive can cause problems over time. Polished marble, granite with a glossy finish, and aluminum cookware can develop a dull haze from repeated scrubbing with baking soda. The issue isn’t deep scratching but the gradual wearing of the polished surface layer. For these materials, a non-abrasive liquid cleaner is a better choice.
In industrial settings, sodium bicarbonate is actually used as a sandblasting medium, typically at 120 to 220 grit. At high pressure, even a soft abrasive can strip paint, remove rust, and clean metal surfaces. The advantage over harder blasting media like sand or glass beads is that sodium bicarbonate is less likely to warp thin metal or damage underlying surfaces. This same principle applies at home: baking soda cleans through gentle, repeated contact rather than brute force.
When Abrasiveness Matters
The practical answer to whether baking soda is “too abrasive” depends on what you’re comparing it to and what you’re using it on. For teeth, it’s one of the gentlest options available. For skin, the abrasion is minor but the pH disruption is the real problem. For most household surfaces, it cleans effectively without damage. For delicate polished stone or soft metals, even its mild grit can cause wear with repeated use.
If you’re choosing baking soda specifically because you want something gentler than commercial abrasive cleaners or whitening toothpastes, it delivers on that promise. Its Mohs hardness of 2.5 and particle size in the 50 to 100 micron range make it one of the mildest abrasives in common use.