Solid lotions are often believed to last longer per ounce than liquid lotions. This is because they are typically more concentrated and contain less water, requiring less product per application to achieve the desired moisturizing effect. Some sources suggest that 1 ounce of solid lotion might last 3 to 10 times longer than 1 ounce of liquid lotion, though the exact ratio is uncertain.
Liquid lotions are less concentrated and often contain a higher percentage of water, which evaporates more quickly. This means you might use more product per application to achieve the same level of hydration compared to a solid lotion.
Based on these general observations, a 1 oz solid lotion is likely to last longer than an 6 oz liquid lotion, even though the liquid lotion is significantly larger in volume.