Venetian blinds are window coverings that can be adjusted. If the blinds are too large for the window, they may look awkward, get stuck on the window frame or get damaged. You can cut the blinds down to size so they properly fit in the window frame.
Lay the blinds and the blind headrail -- where the blinds and pull mechanism leads into -- on a flat surface.
Fold the blinds up so all the slats are gathered together as they are when the blinds are pulled fully open on a window. Use the rubber band to hold the slats together. Wrap masking tape around the ends of the gathered up slats to minimise chipping.
Measure the length of the window, and the length you want the blinds. Make a mark with a pencil on the headrail to indicate the length.
Place the headrail and blinds on a circular saw table and clamp the headrail onto the table. Do not clamp the slats as this can damage them. Pull out the end stiffener -- the metal piece between the front and back of the headrail -- located on the edge of the headrail where the cut is being made.
Position the hacksaw over the pencil mark on the headrail and saw off the shortest end of the headrail near the pencil mark.
Measure the width of window that needs to be covered by the blinds and make a mark across the blinds. It is fine if this mark is over the masking tape.
Verify the headrail is clamped in place on the saw table. Use a circular saw or hacksaw to cut off the end of the blind slats just on the outside of the line mark; this accounts for the width of the blade.
Wear a dust mask and eye protection while cutting. The headrail edge and blind slats edges may be sharp after cutting.