For most people, the right weight is one that feels “challenging but controlled” for the reps you’re doing, not a specific number on the dumbbell.

Fast guideline

Use this rule on almost any exercise:

  • Pick a weight you can lift for about 8–12 reps with good form. The last 2–3 reps should feel hard, but you should still be in control (no swinging, no holding your breath, no pain).
  • If you could easily do 5+ more reps at the end of a set, the weight is probably too light.
  • If you can’t reach your target reps or your form breaks early, it’s too heavy.

Think of effort on a 1–10 scale (RPE: “rate of perceived exertion”):

  • Aim for about 7–8 out of 10 for most sets as a beginner (you could do 2–3 more reps if you had to).

Example starting points

These are ballpark, not rules:

  • Dumbbells: many beginners use around 2–5 kg (5–11 lb) per hand to start, testing if they can do 10–12 clean reps.
  • For common dumbbell moves (squats, rows, presses, lunges), 5–10 kg per hand is a typical starting range for many adults, adjusting up or down based on feel.

For big barbell lifts once you know technique:

  • Squat: beginner goal is roughly 0.75–1× your body weight for 3 reps with solid form (long‑term target, not day one).
  • Bench press: about 0.5–1× body weight for 3 reps as a general goal range over time.
  • Deadlift: about 0.75–1.5× body weight for 3 reps as you progress.

How to find your weight in practice

You can use this simple step‑by‑step method:

  1. Choose a light weight you’re sure you can move easily.
  2. Do 10 reps.
  3. Ask yourself:
    • “Could I do more than 3–4 extra reps?” → Go a bit heavier next set.
    • “Am I struggling already, losing form, or holding my breath?” → Go lighter.
  1. Once you find a weight where reps 8–12 feel tough but controlled, stick with it for 2–3 sets.

A small “dumbbell test” like this is commonly recommended by trainers for new lifters.

When to increase weight

  • If you can do all your sets at the top of your rep range and still feel like you had several reps left, increase the weight slightly next session.
  • A typical safe increase is no more than about 10% at a time, or just “one step up” on the dumbbell rack for beginners.

Safety basics

  • Start lighter than you think, learn the movement, then build up. This reduces injury risk and helps you groove good form.
  • Stop if you feel sharp pain, pinching, or anything that feels “wrong” rather than just “hard.”
  • If possible, have a coach or experienced friend check your form at least once.

A helpful way to think about it:
“The right weight is one that lets me move well, breathe, and finish the set feeling challenged—not destroyed.”

If you tell me your age, approximate fitness level, and what equipment you have (dumbbells, machines, barbell, or just bodyweight), I can outline exact starting weights and sets/reps for a beginner workout tailored to you.