I recommend bringing along an extra 30 percent minimum to assure not running out. The Outdoor Enthusiast has a good piece on the Whisperlite stove also. MSR's web site has slightly different recommendations. While we're on the subject of MSR Whisperlite stoves. The subject always comes up on how to simmer with these things.
Most beginners get either blow torch or off.
Many years ago, MSR provided a heat spreader with the stove to help prevent this problem. It was a stainless steel disk about the size of a Mason jar lid, about one tenth inch thick and four inches in diameter. Just be sure to use aluminum, stainless steel or plain steel. Do not use galvanized steel, brass, bronze, cadmium plated steel, or other toxics generating materials. This spreads out the hot spot and helps prevent burning the food.