Skip to content
PokerLevelUp
Level 2Strategy 3 min readLesson 4 of 8

Preflop Raising Basics: Open Sizes, Limpers and Isolation

How much to raise before the flop online and live, why limping loses money, how to punish limpers with isolation raises and how to steal the blinds.

By PokerLevelUp Team,

Preflop Raising Basics: Open Sizes, Limpers and Isolation — cover art

You know which hands to play and why your seat matters. This lesson covers how to enter the pot: how big to make your first raise, what to do when players have limped in front of you, and why the best players almost never limp themselves. Get these defaults right and you’ll start most hands with the initiative — which makes everything after the flop easier.

Key takeaways

  • Open-raise to about 2–2.5bb online and 3bb live, adding 1bb for each limper.
  • Raising gives you two ways to win; limping gives up the initiative and fold equity.
  • Isolate limpers with a raise so you play the pot heads-up and in position.
  • Steal the blinds from the cutoff and button with a wide range.
  • Keep your open size the same for strong and weak hands so it gives nothing away.

Why raise instead of limp?

Limping — just calling the big blind — looks cheap and safe. In practice it’s one of the most expensive habits in poker:

  1. No fold equity. A raise can win the blinds straight away. A limp never can.
  2. You invite everyone in. Multiway pots make your good hands win less often.
  3. The big blind sees a free flop with any two cards.
  4. You lose the initiative. The player who raised last before the flop can bet the flop and represent strength. A limper can’t.
  5. Your range is capped. Opponents assume you’d have raised your best hands, so they attack you.

The standard approach for the player who’s first in is simple: raise or fold.

How much to open

GameTypical open sizeWhy
Online 6-max cash2–2.5bbPlayers defend well; smaller sizes risk less to steal
Online from the small blind2.5–3bbYou’ll be out of position, so charge the big blind more
Live cash3–4bbLive players call more; bigger sizes punish loose calls
Tournaments with antes2–2.3bbThe antes already make the pot worth winning

Pick one size per situation and use it with your whole range. If you raise more with aces and less with small pairs, observant opponents will read your hand from your bet.

Facing limpers: isolation raises

When one or more players have limped in front of you, you have three options: fold, limp behind, or raise. With good hands, raise — it’s called an isolation raise (an “iso”) because it aims to play the pot heads-up against the weakest player.

Size: your normal open plus one big blind for each limper. Live, many players use 4–5bb plus one per limper, because live limpers call so often.

Isolating a limper

No-Limit Hold'em · live · 1/2 · 200 stacks

Hero (BTN)AJ
  1. Preflop

    Pot 3

    • UTG limps for 2
    • Folds to Hero on the button, who raises to 10 (4bb + 1bb for the limper)
    • Blinds fold, UTG calls
  2. Flop

    Pot 23

    K72
    • UTG checks
    • Hero bets 8 — the limper's range is weak and this board rarely helped it
    • UTG folds
Hero won a 23 pot without a pair: position plus the initiative did the work.
Pot 23DCOBTNYOURaises to 10SBBBUTGLimps 2HJ
An isolation raise: the button raises over one limper to play heads-up and in position.

Limpers are usually weaker than raisers: strong hands tend to raise. That’s why you can iso-raise a wider range than you’d open from the same seat — especially in position. Good hands to isolate with include pairs, suited aces, broadway cards and suited connectors on the button.

Stealing the blinds

When it’s folded to you in the cutoff, button or small blind, only one or two players are left to act, and they’ll be out of position after the flop. Raising here with a wide range is called stealing, and it’s where tight-aggressive players make much of their money.

A rough guide to how often to open when it’s folded to you in 6-max:

SeatShare of hands
UTG~15%
Hijack~20%
Cutoff~27%
Button~35–45%
Small blind~35–45% (depends on the big blind)

Button opening range (6-max, 100bb)466 combos · 35.1% of hands

The same range as our preflop chart — about 35% of hands, a solid starting point you can widen against tight blinds.

Compare every seat in the preflop charts tool, then drill them in the preflop trainer.

Common preflop mistakes

  • Open-limping from any seat. Raise or fold.
  • Min-raising live. A 2bb raise at a live table invites four callers.
  • Different sizes for different hands. Consistency hides your strength.
  • Iso-raising out of position with weak hands. The small blind is a bad seat to isolate with K8o.
  • Folding too much on the button. It’s your most profitable seat; use it.
Quick check

Live 1/2 game. Two players limp and it's folded to you on the button with A♠ Q♠. What's a good raise size?

Quick check

Why is a raise better than a limp when you're first in?

Next up: what to do when someone else raises first — 3-Betting and Facing Raises.

Finished this lesson?

Mark it complete to track your Level 2 progress.

Practise with a free tool

Keep going

Ready for the next level?

Up next in Level 2 — Solid Basics:

3-Betting and Facing Raises: Call, Re-Raise or Fold
Newsletter

Get the weekly level-up

One short email a week: a new lesson, a hand to think about and a tool tip. No spam, unsubscribe any time.

By subscribing you agree to our privacy policy.

Position in Poker: Why Your Seat Matters — cover art
Level 2Strategy

Position in Poker: Why Your Seat Matters

Why acting last is such a big advantage, the name of every seat at the table, and how to adjust your hand selection and betting to your position.

PokerLevelUp

18+ only

Are you 18 or older?

This section links to real-money poker operated by independent partners. You must be of legal age to gamble where you live, and online poker must be legal in your jurisdiction.

Poker should be entertainment, never a way to make money. Play responsibly.