Should you size up or down for prom dresses?

It ultimately depends on your body shape and the style of the dress. It is recommended to try on multiple sizes to see which fits you best. Some dresses may run small while others may run large, so it is important to try on different sizes to ensure the best fit. Ultimately, you should choose the size that is the most comfortable and flattering for your body.

I ordered a dress online, the measurements for it are Bust: 30in, Waist: 27in, Hips: 30in

My measurements are Bust: 34in, Waist: 38in, Hips: 36in

Do you think it'll fit?

Based on the measurements you provided, it is likely that the dress may be too small for you. The dress measurements are smaller than your own measurements, so it is possible that the dress may be tight or not fit properly. It is always recommended to refer to the size chart provided by the retailer and compare your measurements to ensure a proper fit. If the dress does not fit, you may need to consider returning it or exchanging it for a larger size.

But, I heard sizing down is better then sizing up..

Sizing down is not always better than sizing up, as it really depends on the specific dress and your body shape. In general, it is usually easier to take in a dress that is slightly too big than to try to let out a dress that is too small. However, if a dress is significantly smaller than your measurements, there may not be enough fabric to let out and alter the dress to fit properly.

In this case, since the dress measurements are smaller than your own measurements across the board, it is likely that the dress may be too small for you, and I would recommend considering returning or exchanging it for a larger size that will be more likely to fit comfortably.

The dress was described to be stretchy. I didn't think being 6 inches off my measurements would be to bad.

If the dress is described as stretchy and you believe that it may have some flexibility in sizing, it is possible that the dress could still fit you even with the 6-inch difference in measurements. Stretchy fabrics can often accommodate a range of body shapes and sizes.

It may be worth trying on the dress to see how it fits and stretches over your body. If the dress is stretchy enough to comfortably accommodate your measurements, then you may be able to wear it without any issues. However, keep in mind that the fit may be snug or tighter than desired, so it's important to consider your comfort level when deciding whether to keep or return the dress.