The phone case has 5 sizes.
XS size for iPhone 5, 5C, SE or other smaller phones
Small size: 5.37 x 2.75 x 0.50 inch
For Samsung Galaxy J7, S8+, S9+, S10+ iPhone 6, iPhone 7, iPhone 8 or other similar size cell phones.
Medium size: 5.75 x 3.00 x 0.50 inch
For Samsung S8, S9, S10, iPhone X/Xs or other similar size cell phones.
Large size: 6.25 x 3.25 x 0.75 inch
For iPhone 6 Plus, iPhone 7 Plus, iPhone 8 Plus, iPhone Xs Max, iPhone Xr or other similar size cell phones.
XL size: 6.75 x 3.625 x 0.75 inch
For iPhone 6 Plus with case on it, iPhone 7 Plus with case on it, iPhone 8 Plus with case on it, Samsung Note 8, Note 9 with phone case on it.
So iPhone 5C is a naked phone, the black color XS size will be better.
If iPhone 5C with a cover on it, please choose the small size, choose model iPhone 6.
So please double check the dimension of your phone or your phone with a cover on it.
If any other issues, please feel free to contact us.