If you're brand new to resistance training, and plan on using weight training as a means to achieve increases in strength, power, muscle mass, fat loss, endurance, speed, or other physical performance improvements, use the chart below to estimate your starting weight at a given rep count. The rep ranges you'll use regularly in your workouts will depend on the specific circumstances of what your goals, abilities, and limitations are.
For beginners, in the name of safety, I would recommend slowly ramping up over a few months to a 5 to 10 repetition max to start with, and use that as your initial base strength measurements. This shouldn't necessarily be done in a single workout. There's a huge benefit for beginners to stick with light weights and higher reps at first to prepare their tissues for the more strenuous workouts to come, as well as build a solid foundation of consistent good technique.
After 6 to 12 months if your technique is solid, you're not getting overly sore from basic workouts anymore, you've been consistent with training, and are making weekly strength gains then you can consider trying to test a conservative 1 to 4 rep max.
Just remember strength training is a marathon, not a sprint. It's a life long endeavor and should be approached with patience, intelligence, and respect. It's capable of giving you an immensely profound transformation for the better if used wisely. On the other hand if approached recklessly with too much ego and too little sense, it can injure or even cripple you and cause life long suffering.
If you have any questions, don't hesitate to contact me through email or the Bellevue Fitness Training facebook page.