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Momentum indicators
Know Sure Thing Indicator (KST): Formula, Reading and Limits
The know sure thing indicator, or KST, is a momentum oscillator developed by Martin Pring and first described in 1992. It takes four rate-of-change lines, smooths each one with a simple moving average, weights them 1, 2, 3 and 4, and sums them. A 9-period moving average of that sum is the signal line.
In brief
What is the know sure thing indicator?
The KST is Martin Pring's momentum oscillator. It combines four smoothed rate-of-change lines, weights them, and compares the total with a signal line. Here is how it is built, how it is read, and where it misleads.
Key takeaways
- The KST is four smoothed rate-of-change values, weighted 1, 2, 3 and 4 from the shortest to the longest horizon, and summed into one line.
- The standard settings are KST(10,15,20,30,10,10,10,15,9). Pring suggested different sets for weekly and monthly charts, and sources differ on the signal period for his daily chart.
- TA-Lib's notes say nothing divides the sum by the total of the weights, and the KST has no fixed upper or lower bound. Its size depends on the rate-of-change values.
- Zero-line and signal-line crossovers are the usual readings. TradingView says zero-line crossovers have a lot of lag, and StockCharts says that with weekly and monthly settings the lag for centreline crossovers is often too great.
- The KST describes past price changes. It does not forecast prices, and no reading in this guide is a tested trading signal.
How the know sure thing indicator is built
The KST starts from four rate-of-change (ROC) lines. A ROC measures the percentage change in price over a set number of bars. TA-Lib defines each one as (price at bar t divided by the price X bars earlier, minus 1), multiplied by 100. Pring used four horizons, so the KST looks at short, intermediate and longer-term momentum in one line.
Each ROC is then smoothed with a simple moving average (SMA). StockCharts calls the smoothed lines RCMA1 to RCMA4. The four lines are added with weights of 1 to 4, so the longest horizon carries the most weight in the total. The table gives the default periods from the sources checked for this guide.
| Component | Rate-of-change period | Smoothing SMA period | Weight |
|---|---|---|---|
| RCMA1 | 10 | 10 | 1 |
| RCMA2 | 15 | 10 | 2 |
| RCMA3 | 20 | 10 | 3 |
| RCMA4 | 30 | 15 | 4 |
| Signal line | KST line | 9 | Not weighted |
Defaults from StockCharts ChartSchool and TradingView support, checked 10 November 2026. TA-Lib gives the same ROC and SMA periods.
In full, KST = (RCMA1 × 1) + (RCMA2 × 2) + (RCMA3 × 3) + (RCMA4 × 4). The signal line is a 9-period SMA of the KST, not of price. Each figure in the sum is a weighted value, so a large move in the 30-period leg moves the KST more than the same move in the 10-period leg.
StockCharts calls KST simply a weighted average of four different rate-of-change values that have been smoothed, but TA-Lib states that nothing divides by the total of the weights. This guide follows the weighted sum.
Default settings and Pring's variants
Pring's KST is usually written as KST(ROC1, ROC2, ROC3, ROC4, SMA1, SMA2, SMA3, SMA4, signal). The standard set is 10, 15, 20, 30, 10, 10, 10, 15 and 9. StockCharts also lists weekly and monthly settings, labelled medium-term and long-term. They apply the same method to weekly or monthly bars, with different period numbers. The sources do not all give the same signal period for the daily chart, so the table shows each one.
| Source | Settings written as KST(...) | What the source states |
|---|---|---|
| StockCharts, daily (default) | KST(10,15,20,30,10,10,10,15,9) | The standard set, with a 9-period signal line |
| StockCharts, weekly | KST(10,13,15,20,10,13,15,20,9) | Pring's medium-term set, with a 9-period signal line |
| StockCharts, monthly | KST(9,12,18,24,6,6,6,9,9) | Pring's long-term set, with a 9-period signal line |
| TradingView support | KST(10,15,20,30,10,10,10,15,9) | Calls these the default parameters, says the time frames are at the trader's discretion, and reports that Pring recommended switching settings between daily, weekly and monthly charts |
| TA-Lib | ROC 10, 15, 20, 30; SMA 10, 10, 10, 15; signal 9 | Notes that Pring's daily page uses a 10-day signal, and gives a default signal period of 9 |
Verified on 10 November 2026 from the pages named. The weekly and monthly sets appear on StockCharts and the TradingView support page. Check your platform's inputs, because each one can differ.
Know sure thing indicator worked example: four ROC values
This is an illustrative example with invented values, not market data. Suppose the four smoothed ROC lines on the latest bar read RCMA1 = 2.00, RCMA2 = 1.00, RCMA3 = -0.50 and RCMA4 = -1.50, all in percent. Each weighted value is the smoothed reading multiplied by its weight, and the KST is their sum.
| Component | Smoothed value | Weight | Weighted value |
|---|---|---|---|
| RCMA1 | 2.00 | 1 | 2.00 |
| RCMA2 | 1.00 | 2 | 2.00 |
| RCMA3 | -0.50 | 3 | -1.50 |
| RCMA4 | -1.50 | 4 | -6.00 |
| KST (sum) | Not applicable | Total weight 10 | -3.50 |
Example: all values are invented. The sum is not divided by the total weight of 10.
KST = 2.00 + 2.00 - 1.50 - 6.00 = -3.50. The weighted total is negative in this example. Because the sum is not divided by 10, the value stays on the scale of the rate-of-change values multiplied by their weights, which is why KST readings are not comparable with a bounded oscillator.
The signal line is the 9-period SMA of KST. Suppose the nine most recent KST values, oldest first, are -6.00, -5.50, -5.00, -4.50, -4.00, -4.20, -3.80, -3.60 and -3.50. Their sum is -40.10, and -40.10 divided by 9 is -4.46 to two decimal places. The latest KST of -3.50 is above that signal of -4.46.
Over these nine bars the KST rises from -6.00 to -3.50. StockCharts describes a rising KST that is still negative as a sign that downside momentum is waning. In this example that describes the numbers given. It does not show what price will do next.
Zero-line and signal-line readings for KST
The two usual readings are a crossing of the zero line and a crossing of the signal line. StockCharts says KST generally rises when it is above its signal line and falls when it is below. It describes a positive KST as favouring bulls and a negative KST as favouring bears.
- Zero line: a move above zero means the weighted total has turned positive, and a move below zero means it has turned negative. This is the basic reading, but TradingView's support page says zero-line crossovers typically have a lot of lag and are not always reliable.
- Signal line: TradingView's support page says signal-line crossovers can signify an underlying change in momentum. That describes a change in the indicator, and this guide does not present signal-line crossovers as a method that works.
- Waning momentum: a rising KST that is still negative suggests downside momentum is fading. StockCharts says a falling KST that is still positive indicates that upside momentum is waning.
For its weekly and monthly settings, StockCharts says chartists should use signal line crossovers to detect directional changes in price, and that the lag for centreline crossovers is often too great. It also says it is probably best to use divergences when there is a large and blatant divergence. This guide does not present any of these readings as a method that works.
Limits: unbounded values, lag and strong trends
- No fixed scale. KST is unbounded, so StockCharts says it is relatively ill-suited to identifying overbought or oversold conditions. A value of -3.50 has no universal meaning across instruments or timeframes.
- Divergences. The StockCharts page says most rate-of-change divergences do not lead to price reversals.
- Strong trends. StockCharts says KST can move into positive territory and remain there for an extended period during a strong uptrend. A reading that stays positive in such a trend does not show that the trend has ended.
- Lag. Four smoothing averages and a 9-period signal line add delay. The longer the period, the more the reading trails the price.
- Settings. Changing any of the nine parameters changes every reading. Check the inputs before comparing one chart with another.
StockCharts says KST is not a perfect indicator and should be combined with other analysis. The smoothing step is an averaging method, and the exponential moving average guide explains a different average. For a bounded momentum oscillator built from the high and low range, see the stochastic oscillator guide.
Other rate-of-change tools handle the same input differently. The TRIX guide takes a triple-smoothed EMA and plots its one-period percent change, and the Coppock Curve guide applies a 10-period weighted moving average to the sum of a 14-period and an 11-period rate of change. Each has its own formula, so do not read one with the KST's settings.
Risk disclosure
- The KST describes past prices. A crossover or a negative reading does not show that price will rise or fall, and nothing in this guide is a tested trading signal.
- KST has no fixed bounds. StockCharts says it is relatively ill-suited to identifying overbought or oversold conditions, so a high or low reading does not mark a turning point.
- Changing the rate-of-change periods, the smoothing periods, the weights or the signal period changes every reading. Check the settings on your own platform before you compare sources.
- In strong trends, KST can stay on one side of zero for long periods. Acting on crossovers can mean trading against a move that continues.
- The worked example uses invented values and is not a recommendation. Real charts will show different numbers.
- This page is educational and is not personal financial advice. Trading can lose money, and leveraged positions can lose more than the amount you deposit.
RTX5 status
This guide explains the know sure thing indicator in general and does not describe an RTX5 feature. No RTX5 release record confirms which indicators, chart types or alerts the product includes. Its Windows desktop client is in preview, and the web and mobile clients are planned. A Google Play listing for Android is published, but the mobile client has no approved release record yet; check the product-availability record before relying on any RTX5 feature.
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Primary references
Sources were checked on 10 November 2026. They explain market rules and concepts; they do not certify RTX5 or provide individual financial advice.
StockCharts ChartSchool: Pring's Know Sure Thing (KST)Gives the RCMA1 to RCMA4 definitions, the KST sum with weights 1 to 4, the 9-period signal line, the default KST(10,15,20,30,10,10,10,15,9), the weekly and monthly sets, Martin Pring as developer, the 1992 Stocks & Commodities article, the zero-line and signal-line readings, the unbounded scale and the divergence advice. Checked 10 November 2026.TA-Lib: KST (Know Sure Thing)Defines ROC_k as (price divided by the price X bars earlier, minus 1) multiplied by 100, RCMA_k as an SMA of ROC_k, KST as the weighted sum with weights 1 to 4 and no division by the total, and the signal as an SMA of KST with default period 9. Notes that Pring's daily page uses a 10-day signal. Checked 10 November 2026.TradingView support: Know Sure Thing (KST)States the default parameters 10,15,20,30,10,10,10,15,9, Martin Pring as developer and the 1992 Stocks & Commodities introduction. Says zero-line crossovers typically have a lot of lag and are not always reliable. Says signal line crossovers can signify an underlying change in momentum. Says the time frames are at the trader's discretion, and that Pring recommended switching settings between daily, weekly and monthly charts. Checked 10 November 2026.RTX5 product availabilityRTX5 status record. Use it to check which RTX5 products and clients are live before relying on any feature.
Questions readers ask
What is the formula for the know sure thing indicator?
KST is (RCMA1 × 1) + (RCMA2 × 2) + (RCMA3 × 3) + (RCMA4 × 4). Each RCMA is a simple moving average of a rate of change: a 10-period SMA of a 10-period ROC, a 10-period SMA of a 15-period ROC, a 10-period SMA of a 20-period ROC, and a 15-period SMA of a 30-period ROC. The signal line is a 9-period SMA of KST.
Who created the KST indicator?
Martin Pring created it. StockCharts says he first described it in 1992, in an article titled Summed Rate of Change (KST) in Stocks & Commodities magazine. TradingView's support page gives the same developer and year, and describes the indicator as introduced in Stocks & Commodities. The article title includes the KST abbreviation.
What are the default KST settings?
The standard set is KST(10,15,20,30,10,10,10,15,9): four rate-of-change periods, four smoothing periods and a 9-period signal line. StockCharts also gives weekly and monthly sets. TA-Lib notes that Pring's daily page uses a 10-day signal, while the charting platforms default to 9, so check the inputs on your own platform.
Is a KST crossover a buy or sell signal?
No. This guide does not present any crossover as a signal that works. TradingView's support page says signal-line crossovers can signify an underlying change in momentum. A crossover uses past prices only, so it cannot show what price will do next, and zero-line crossovers can lag.
Why is the KST value not limited to a fixed range?
TA-Lib's notes say nothing divides the KST by the sum of its weights, and the KST has no fixed upper or lower bound. Its size depends on the size of the four smoothed rate-of-change values. StockCharts says it is therefore relatively ill-suited to overbought and oversold readings. A value on one instrument or timeframe does not compare directly with the same value elsewhere.
Keep learning
Exponential moving averageThe averaging method that many momentum indicators use, compared with the simple moving average the KST uses.Stochastic oscillatorA bounded momentum oscillator with its own smoothing and signal line, which makes its scale easier to compare.Williams %RA range-based momentum oscillator on a fixed 0 to -100 scale, in contrast with the unbounded KST.What is MACD?Another momentum tool with a signal line and a zero line, useful for comparing how the two are read.