Initial Balance and Range Extension: How They Are Measured

Before you read: TPO Profile Basics: Letters, Periods and Profile Shape

ILLUSTRATIVE · Worked numbers are constructed for teaching · Not real market data · Not a recommendation or signal

What you will learn

• What the initial balance (IB) is, and the settings that decide where it starts and ends.
• How to measure the IB range, the IB midpoint and range extension, with worked arithmetic.
• Why these measurements describe a session and do not, by themselves, say what the rest of the session does.

The terms come up briefly in opening types and day types. This lesson slows down and shows how the numbers are taken.

What is the initial balance?

If you had to summarize the first stretch of a session with two numbers, which two would you pick?

The initial balance is the price range of the opening part of a session: its highest price and its lowest price over that window. In TPO profile terms it is often defined as the first two 30-minute periods, so the first hour. Some traders use only the first 30 minutes, and some use other lengths.

The IB is a reference, not an event. Nothing special happens to the market at the end of the first hour. The IB is simply a fixed, early window that lets you compare one session with another on the same terms.

Which settings decide the IB?

Two traders quote different IB highs for the same day. Is one of them wrong?

Not necessarily. Three choices change the numbers:

• Window length. One hour, 30 minutes, or another length.
• Session start. For index futures, which trade nearly around the clock, many profile users measure the IB from the open of regular trading hours. Others measure from the start of the electronic session. The two give different IBs on most days.
• Data source. A front-month contract, a continuous contract and a cash index can show slightly different highs and lows.

Before you compare IB figures from two sources, check that all three settings match. When you journal your own sessions, write the settings down once and keep them fixed.

How do you measure the IB?

What arithmetic turns two prices into a description of the opening hour?

The worked numbers below are a constructed illustration, on a made-up scale around 100.

• IB high: 101.00
• IB low: 98.50
• IB range = IB high − IB low = 101.00 − 98.50 = 2.50
• IB midpoint = (IB high + IB low) ÷ 2 = (101.00 + 98.50) ÷ 2 = 99.75

Some traders also compare the IB range with a typical recent IB range, for example the average of the last 20 sessions. If that average were 2.00, this IB would be 2.50 ÷ 2.00 = 1.25 times the recent average, a somewhat wide opening hour by that yardstick. The ratio is a description of the opening hour relative to recent ones. It is not a forecast of the rest of the day.

What is range extension?

What is it called when price leaves the opening range, and how far is “far”?

Range extension is trading beyond the IB after the IB window ends. Extension above the IB high is upside range extension. Extension below the IB low is downside range extension. A session can extend on one side, on both sides, or not at all.

Continuing the constructed illustration:

• After the first hour, price trades up to 102.25.
• Upside extension = 102.25 − 101.00 = 1.25.
• As a multiple of the IB range: 1.25 ÷ 2.50 = 0.5 times the IB range.
• Price also trades down to 98.25 in the afternoon. Downside extension = 98.50 − 98.25 = 0.25, or 0.1 times the IB range.
• The full session range is 102.25 − 98.25 = 4.00, which is 1.6 times the IB range.

Writing extension as a multiple of the IB range makes sessions with different volatility easier to compare. “Extended 1.25 points” means different things in a quiet week and in a busy one. “Extended half an IB” travels better.

Initial balance diagram

Illustrative diagram constructed for teaching. Not real market data.

The diagram shows a constructed session with the first hour shaded as the IB, the IB high, low and midpoint marked, and the upside and downside extensions labeled with the arithmetic from this lesson.

How do IB and range extension relate to day types?

Why do day-type labels lean so heavily on the opening hour?

Day-type labels lean heavily on the IB. Opening types and day types describes balanced, trend, double-distribution and neutral days. TradingView’s TPO indicator documentation uses a different set of four labels, each written partly in IB terms. Roughly:

• A normal day forms most of its range inside the IB (that page says about 85%), with little extension.
• A normal variation day extends beyond the IB by anything from a few ticks up to about double the IB range.
• A trend day extends far in one direction, with an elongated profile.
• A neutral day extends beyond the IB, reverses, and may also extend beyond the other side. Many writers use the label only when both sides are extended.

For example, that page describes a trend day as one where range extension is “more than double the size of the IBR” (the initial balance range) and the close is near the extension’s extreme. Different authors draw the boundaries in different places, so the same session can get two labels from two writers. Every label is applied after the close.

What do people claim about the IB, and how should you treat it?

If you read that a narrow opening hour “leads to” a big day, what would you need to see before you accepted it?

Trading writing contains many claims that link the IB to what follows, for example that extension follows a narrow IB, or that the midpoint acts as a magnet. Treat each one as a hypothesis, not a fact. To check one honestly you would need a fixed definition, a large sample, results on data you did not use to form the idea, and a comparison with what happens on all days, not just memorable ones. Honest backtesting covers how to set that up. This Academy does not claim any such relationship holds.

What are the limits of IB measurements?

What can two numbers from the first hour leave out?

• Settings drive the result. A different window, session start or data source gives a different IB.
• The overnight session is ignored. A regular-hours IB says nothing about what traded overnight unless you add that separately.
• One event can dominate. A scheduled release during the first hour (see economic events and headlines) can stretch the IB for reasons unrelated to the usual opening auction.
• Multiples hide size. A ratio of 2.0 on a tiny IB can be a smaller move in points than a ratio of 0.5 on a huge IB.
• Labels come after the fact. Extension and day type are known only once the session has finished.

What this does not tell you about the initial balance

• An IB high or low is not a level price has to revisit, hold or break.
• A wide or narrow IB does not settle what the rest of the session does.
• Range extension describes where price went after the first hour, not why.
• An IB multiple is a description, not a target.

Method in Practice: range extension as a condition

Fictional example. John, Harbor Index futures, the prices, times, costs and results are all invented for teaching. This shows how a written plan can be built and tested. It is not a recommendation, and nothing here says how often this idea works.

Try it on a real chart. Test this idea yourself on past sessions with bar replay. Keep your own count, including the days with no trade.

The idea. Some traders wait for the first hour to finish, then use the initial balance (IB) as a condition: when a later 30-minute period closes beyond it, they treat that as range extension. This plan also checks whether the first hour was unusually wide, and skips wide ones.

John's plan

Setup

IB = 08:30–09:30 CT. Today: high 100.60, low 99.60, range 1.00 (0.83× the 20-session average of 1.20)

Enter if

the IB range is no more than 1.0× the average, and after 09:30 a 30-minute period closes above 100.60. Buy.

Wrong if

a 30-minute period closes back below 100.60, inside the IB

Manage

take half at 101.10 (IB high + half the IB range), the rest at 101.60 (+1 IB range) or by 14:30

Risk

$150 maximum, costs included

Three outcomes

• ✅ Worked: the extension kept going → +$94

• ❌ Failed: price closed back inside the IB → −$84, inside the limit

• ⏸ No trade: the IB was 1.33× the average, too wide for the plan → $0

Show the full replays

Item	Plan
IB	08:30–09:30 CT, regular session, front month. High 100.60, low 99.60, range 1.00, midpoint 100.10
Width filter	IB range ÷ 20-session average IB range (1.20) must be 1.0 or less. Today 0.83
Entry condition	After 09:30, a 30-minute period closes above 100.60. Buy 2 at market after that close
Wrong if	A 30-minute period closes below 100.60. Exit at market after that close
Management	Take profit on half at 101.10 (limit) and move the exit for the rest to the entry price (stop). Rest at 101.60 (limit). Time limit 14:30 CT
Risk cap and size	$150. Exiting just under 100.60 is planned to cost about $40 per contract, so 2 contracts
Not trading if	IB wider than 1.0× average, scheduled major release within the hour, or no setup by 12:00 CT

Replay A: worked

Time (CT)	What happened	John
08:30–09:30	IB forms: 99.60–100.60	Filter passes (0.83×)
09:30–10:00	Pushes above, closes 100.78	Buys 2 at market, filled 100.83
10:00–10:40	Trades 101.10 at 10:40	Sells 1 at 101.10 (limit). Exit for the other moves to 100.83
10:40–13:15	Holds above 100.90, trades 101.60 at 13:15	Sells the last 1 at 101.60 (limit)

Result after costs: +0.27 point = +$27, +0.77 point = +$77, commissions −$10. Net +$94. Journal: "Extension carried a full IB range. Both exits were limit orders, so no slippage on the way out."

Replay B: failed

Time (CT)	What happened	John
08:30–09:30	IB 99.60–100.60	Filter passes
09:30–10:00	Closes 100.72	Buys 2 at market, filled 100.77
10:00–10:30	Falls back, closes 100.45	Wrong-if met: sells 2 at market, filled 100.40
10:30–15:00	Extends below the IB low to 99.40	Done for the idea (both sides extended: a neutral-type day)

Result after costs: 2 × −0.37 point = −$74, commissions −$10. Net −$84. Journal: "Upside extension failed and the market went to the other side. The plan treats that as a loss to take, not a reason to reverse."

Replay C: no trade

Time (CT)	What happened	John
08:30–09:30	IB 99.50–101.10, range 1.60 = 1.33× the 1.20 average	Filter fails: no trade today
09:30–15:00	Extends to 101.70	Watches only

Result: $0. Journal: "The filter skipped a day that extended. That's the cost of the filter. The weekly review will count both kinds of day before I judge it."

Test it yourself

• Fix your IB settings (window, session start, data source) and never change them mid-test.
• Replay every session, not just narrow-IB days, and compare results with and without the width filter.
• Count neutral days (extension on both sides) as part of the result.

Where it breaks

• Different IB settings give different highs and lows (this lesson's settings section).
• A news release in the first hour can stretch the IB for reasons unrelated to the opening auction.
• Extensions often reverse (the failed replay). The width filter is a choice, not a law.

Reflection question: Which settings in your plan would change your results if a friend used theirs instead?

Check yourself

Reflect on these; there is no score.

1. IB high 100.50, IB low 99.00. What are the IB range and the IB midpoint? Hint: subtract for the range; average for the midpoint.
2. With that IB, price then trades to 102.00 after the first hour. What is the upside extension in points and as a multiple of the IB range? Hint: start from the IB high, then divide by the IB range.
3. A friend’s IB high differs from yours by a few ticks on the same day. Name two settings to compare. Hint: window length, session start, data source.
4. Why is “IB ratio 1.5 versus the 20-day average” a description and not a prediction? Hint: what does it say about the hours after the IB window?

Trademark note. Market Profile is a name associated with the Chicago Board of Trade (CBOT), now part of CME Group. CBOT and Chicago Board of Trade are trademarks of Board of Trade of the City of Chicago, Inc. Socratic Trading Academy is not affiliated with, sponsored by or endorsed by CME Group or CBOT.

Last reviewed November 9, 2026. Spotted a mistake? Report an error.