Just discovered this. I cut my hand soap bars in half and just put out half sized bars. I was quite surprised that these half sized bars seem to last as long as the full sized bar used to before. I wonder how much extra hot water we were using to wash off the extra soap before. This goes along with bigger holes in tooth paste tubes I think.

last year I bought myself some really lovely hand made soap. i as looking forward to my soap running out so i could get more but the first bar is only half gone. i just make sure to keep my bar of soap very dry except for when i use some soap to wash my hands. so i wanted to add the tip of making sure to keep bar soap dry! it apperently lasts a very long time this way. my husband always leaves the bar in the shower and it starts to dissolve very fast that way.

I moved my soap dish from hanging from the shower head to the far end of the shower, halved my soap consumption. I dont have a bar of hand soap, just lather up from the shower bar.

I use liquid (pump) hand soap. I keep it for refill, and add lots of water. you might have to use one squirt.. or three. but at least you never have more soap than you need on your hands.

I'm sure you all have a pair of socks where one has a hole in the toe or heel, and the other is fine.

Take all of those 'too small to use' slivers of soap and drop them in the good sock.
Makes the best scrub cloth for shower use.

Back in high school, soap was used in calculus as part of a rate of change problem.

By cutting the soap bar in half, you have reduced the surface area by about half. The smaller the surface area, the slower the soap erodes. There is some science behind this.