Altering men's trousers can be a great way to save money, whether you are refitting an entire wardrobe of favourite clothing due to weight loss or making a new pair of trousers fit just a little bit better. The ability to tailor clothing is quickly becoming a lost art, but just a small amount of practice will have you producing professional looking results very quickly.
Make pant legs longer by ripping out the seams in the hems around the cuff at the base of the leg. Have the owner wear the trousers, determine where the correct length should be, and mark this length with the chalk. Pin it in place all around the cuff, with the extra material folded inside the pant leg. Iron the fold so that it looks professional, then sew it around the bottom of the pant leg. Cut off any excess fabric.
To shorten the legs of trousers, have the owner put them on, then fold the extra material inside the pant leg and pin it into place. Iron the fold for a professional look and sew the hem around the cuff. Cut off extra material. The circumference of the pant legs can also be tightened by ripping the outseam that runs along the outside of the leg, pinning it so that it fits more tightly along the leg, and resewing the seam to give a skinnier, more closely fitting pant leg.
Decrease the size of the waist by having the owner put the trousers on inside out. Pull the extra waist material up in a fold at the back of the trousers or on the sides, whichever works best with the creases of the trousers. Pin the fold in place, and iron it for a better appearance. Sew it tightly with multiple passes to ensure a tight fit. If the trousers will be tightened considerably, you may have to rip open the seams and cut out some of the material so that the fabric does not bunch up around the waist.
If there is no extra fabric in the hem of the trousers, they cannot be made longer. Likewise, it is not possible for beginners to make trousers much larger in the waist, as there is no extra material available. With all adjustments, have the owner try the trousers on after each alteration to see if additional changes need to be made. Trousers should touch the ground at the heal and fold up just the smallest amount on the arch of the foot; otherwise, they'll be too short when worn sitting down.
Be careful when pinning clothing on your subject, as it is easy to stick the pins in the subject by mistake.