What is an isolation raise in poker?

An isolation raise (or iso-raise) is a raise made after one or more players limp, with the goal of playing heads-up against a weak limper and taking the initiative. Limpers usually have weak hands, so isolating them with a good range and position is one of the most profitable plays at low stakes.

Example

Blinds $0.05/$0.10. A loose player limps for $0.10. You’re on the button and raise to $0.40. The blinds fold, the limper calls, and you play a heads-up pot in position with the initiative.

Sizing

A common guide: your normal open (about 3 big blinds) + 1 big blind per limper. Against very loose players who call everything, go a little bigger. See bet sizing.

Which hands to isolate with

Strong value hands: pairs, good aces, broadway hands.
In position, you can isolate wider, including suited connectors and suited aces.
Out of position (from the blinds), stick to stronger hands.

Why it works

Limpers’ ranges are weak and capped: they would often raise their best hands. See limping.
You get heads-up, so your hand is stronger relatively.
You have the initiative: a continuation bet wins often.

After the flop

C-bet most flops against one limper; they miss often.
Against a calling station, c-bet less as a bluff and value bet more. See calling stations.
If the limper check-raises, respect it: limp-callers rarely bluff-raise at low stakes.

Watch out for

Limp-raisers: a player who limps and then re-raises big often has A-A or K-K.
Multiple limpers behind you: isolation is harder if several players call.

FAQ

What is an isolation raise in poker?

A raise after one or more players limp, made to play heads-up against a weak limper.

How much should you raise to isolate a limper?

Your normal open plus one big blind for each limper.

Which hands should you isolate with?

Strong value hands, and a wider range in position, including suited connectors and suited aces.

What does a limp-raise usually mean?

A very strong hand, often A-A or K-K.