Helpful Info :

How should you hang a painting?

Remember the '145 rule'
When hanging a painting, the idea is to have its centre at eye level. This is typically at the 145 cm mark measured up from the floor. This isn't where it will hang from, so you'll need to work out where to place the hangers.

The first step is to measure 145 cm from the floor and mark it on the wall.

Next, find the centre of the painting by measuring its height and dividing by two - this is the focal point number.

Now, measure from the top of the artwork to the tightened hanging wire. Subtract this number from the focal point number.

Take the new number and measure that distance above the 145 cm mark. This is where the hanger should be placed, so mark this spot and put your hook in there.

When hanging artwork above furniture, the fireplace, or other obstructions, the eye level rule doesn’t always apply. The bottom of the frame should be between 15 - 20 cm above the top of the feature. In these cases, it’s acceptable to go higher than the 145 guideline if need be.

The artwork should also relate space-wise to furniture, meaning a small work of art hanging 15 cm above a long couch won’t look right. However, a large work of art or multiple works would look great.

When hanging multiple works of art, treat the whole collection as if it were one work of art. Anchoring multiple works round the 145 cm focal point will help the collection appear balanced.

Ideal spacing between multiple artworks is 7-15 cm.

I've used metric measures in this answer, but if you want imperial here are the approximate alternatives:
145 cm ....... 57 inches
15 - 20 cm ... 6 to 8 inches
7 - 15 cm ..... 3 to 6 inches