At a glance
- On the HUD
- OSz
- Formula
average open-raise, in big blinds (the total they raised to)- Typical range
Not colored on the HUD: it has no typical range, because a good number depends on the game. See “Too low, about right, too high” below.
- Where it shows
- Badge: the opener, for the seat they opened.
- Trust it after
- 12 chances. Below that the number is faded; reads need 12 chances and a number at least one standard error outside the typical range.
What it measures
Open size is the amount a player raises to when they’re first in: everyone before them folded, nobody limped, and they raised. The HUD averages those raise-to amounts in big blinds, so a raise to 6 with blinds of 1/2 adds 3 bb.
It’s a sizing stat, not a frequency. Raise first in tells you how often they open; open size tells you what each open costs you to play against. You need both: a player who opens 40% of hands to 2 bb is a very different opponent from one who opens 15% to 5 bb.
It leaves out raises over limpers (those are iso-raises) and any 3-bet or later raise. Open-shoves do count: a short stack going all-in first in adds their whole stack as one open.
How it’s calculated
Open size = average of (raise-to amount ÷ big blind) over every raise-first-in open
- Sample: each open-raise when everyone before them folded and nobody limped. One open adds one sample.
- Value: the total they raised to, not the amount added. A small blind open to 3 bb counts as 3, even though only 2.5 bb went in.
- Big blinds, not straddles: the HUD divides by the big blind even when there’s a straddle, and a raise over a straddle with no limpers still counts as an open. In a 1/2 game with a 4 straddle, a raise to 12 shows as 6 bb.
- Kept by seat, so the badge can show the average for the seat they opened from.
Example: Kim opened 12 times: 11 raises to 3 bb and one all-in for 40 bb from a short stack. Open size = (11 × 3 + 40) / 12 = 73 / 12 = 6.1 bb. Her real habit is 3 bb; one shove doubled the average.
Why it matters
Open size sets the price for everyone behind. With blinds of 0.5 + 1 bb and no antes, here’s what each size asks of a steal, and what the big blind needs to call heads-up on raw pot odds:
| Open to | Steal needs folds | Big blind call needs |
|---|---|---|
| 2 bb | 2 / 3.5 = 57.1% | 1 / 4.5 = 22.2% |
| 2.5 bb | 2.5 / 4 = 62.5% | 1.5 / 5.5 = 27.3% |
| 3 bb | 3 / 4.5 = 66.7% | 2 / 6.5 = 30.8% |
| 4 bb | 4 / 5.5 = 72.7% | 3 / 8.5 = 35.3% |
| 5 bb | 5 / 6.5 = 76.9% | 4 / 10.5 = 38.1% |
Bigger opens need more folds and give the big blind a worse price, so a big opener’s range should be tighter, and so should your defense. A small opener hands you a cheap flop against a wide range.
Too low, about right, too high
The HUD doesn’t color open size or give it a typical range, because the right size depends on stakes, antes, straddles and how loose the table is. These bands are ours, for a game without a straddle; with a 2 bb straddle, double them. Raises over limpers, which run bigger, aren’t in this number at all.
Small: under 2.5 bb
What it says
Online-style opens: min-raises to 2 bb or something like 2.2 bb. Usually a player who studies or plays online, opens a fairly wide range and wants to steal cheaply. In a home game where everyone else opens to 4 bb, a small opener is often the most solid player at the table. It can also be a beginner min-raising everything.
How to exploit it
- Defend the big blind wide. Against a 2 bb open you need 22.2% to call, so most suited hands, connected hands and pairs can play.
- 3-bet them more, for value and with hands like A5s and K9s, especially when their raise first in is high and their fold to 3-bet is in range or above.
- Size your 3-bets to the small open. About 3x in position and 4x out of position is a common baseline, so 3-bets stay cheap too.
Middle: 2.5–4 bb
What it says
The usual range for a live-style game without a straddle. On its own it says little, so look at seat and frequency. A player at 3 bb from every seat is sizing by habit; one who opens 2.5 bb on the button and 4 bb under the gun is sizing by position, which is common and fine.
How to exploit it
- Use frequency, not size. Pair it with raise first in and steal attempt to see how wide each open is.
- Compare each open with their average for that seat. Some players open bigger with their best hands, others with their weakest; a 6 bb open from a 3 bb player is a different range, and showdowns tell you which way they lean.
- Tighten big blind defense a little against the upper end: you need 30.8% at 3 bb and 35.3% at 4 bb.
Large: over 4 bb
What it says
Big opens: 5 bb, 6 bb, sometimes 10 bb. Common in PokerNow home games, especially at loose tables where players open big to thin the field. It often comes from a player who opens a tight range and hates being called by five people. It can also be an average pulled up by shoves or by straddled pots, so check the sample first.
How to exploit it
- Fold more marginal hands, especially in the big blind: at 5 bb you need 38.1% just to call, out of position.
- 3-bet for value with QQ+, AK and AQs, sized as a multiple of their open. A 5 bb open makes a 3-bet to 15–20 bb, so the pot gets big fast.
- If their raise first in is high as well, they’re overpaying to steal: a 5 bb steal needs 76.9% folds. 3-bet them wider and let them fold.
When it’s your own number
Open size has no read, but anyone with the HUD sees your average for the seat you open from. The bigger risk is inconsistency: if you open 3 bb with most hands and 6 bb with aces, a player who watches will notice. Use one size per seat, adjusted for straddles, whatever you hold.
To pick that size, start from the table. Where the blinds defend too much, bigger opens with a tighter range make money; where everyone folds, smaller opens steal cheaper. If your average looks high, check for shoves skewing it first.
Using it on the HUD
Open size shows on the opener’s badge after they open, using their average for the seat they opened from. When that seat has fewer than 12 opens, the HUD steps back to their overall average and the tooltip says so. It shows one decimal and never takes a color.
It fills faster than most preflop stats: a player who opens a fifth of their hands gives you 12 samples in about 60 hands. Averages also settle faster than percentages, unless the player mixes sizes or shoves, as Kim’s 40 bb shove shows.
Read it with raise first in for width, 3-bet size to see whether they size up everywhere, and fold to 3-bet to see how they defend a big open.
Questions
What is a normal open size in poker?
Online, about 2–2.5 big blinds is common. Live and home games often open 3–5 bb, and more with a straddle. The HUD doesn’t mark any open size as normal, so compare a player’s number with the rest of your table and with their own average by seat.
Why is a player’s open size so high on the HUD?
Usually one of three reasons: they really open big, the game has a straddle (the HUD measures in big blinds, so raises over a straddle look large), or a few short-stack open-shoves are pulling the average up. Check how many opens it rests on.
Does a bigger open size win more?
Not automatically. A bigger open wins more when worse hands call but needs more folds to steal: 62.5% at 2.5 bb, 72.7% at 4 bb. In loose games where the blinds call too much, bigger opens with a tighter range tend to do well.