Somewhat tiny. I would estimate 3 mm or so perhaps 4 mm. I tend to take my photos in the field so I am usually not able to measure. This one was taken in a bridge railing. I am basing my estimate by comparing to picture of Lucilia fly that I took in the same location. This spider is about a third of the length of that fly.

There is a lot of difference between those when we're talking something so small. I'd guess dwarf spider for something under 3 mm, but there are some other choices for the ones that are 3-4 mm like Enoplognatha thoracica. However the eyes on your spider appear to have an oval shape which might help us narrow the choices down.