wickra/docs/wiki/indicators/volatility/Indicator-Natr.md

NATR

Normalized Average True Range — ATR expressed as a percentage of price, so volatility is comparable across instruments.

Quick reference

Field	Value
Family	Volatility
Sub-category	Range-average
Input type	Candle (uses high, low, close)
Output type	f64
Output range	[0, ∞) (percent)
Default parameters	period = 14 (Python)
Warmup period	period
Interpretation	Average true range as a percent of the close.

Formula

NATR = 100 · ATR(period) / close

Atr measures volatility in raw price units — a 2.0 ATR is large on a $10 stock and tiny on a $5000 index. Dividing by the current close converts it to a percentage, so a NATR of 2.0 always means "the average true range is 2 % of price". That makes NATR readings comparable across a portfolio, and stop or position-size rules expressed as a NATR multiple behave consistently regardless of price level.

Parameters

Name	Type	Default	Valid range	Description
period	usize	14 (Python)	>= 1	Wilder smoothing period of the underlying ATR. 0 errors with Error::PeriodZero.

The Python binding defaults period to 14.

Inputs / Outputs

From crates/wickra-core/src/indicators/natr.rs:

impl Indicator for Natr {
    type Input = Candle;
    type Output = f64;
    // update(&mut self, input: Candle) -> Option<f64>
}

NATR is a candle-input indicator: it reads high, low and close. In Python the streaming update accepts a 6-tuple or a dict; the batch helper takes high, low, close numpy arrays. Node and WASM expose update(high, low, close) and batch(high, low, close).

Warmup

Natr::new(period).warmup_period() == period — identical to the underlying Atr, which is Wilder-seeded over period true ranges.

Edge cases

• Flat market. A market with no range has ATR = 0, so NATR = 0 (flat_market_yields_zero pins this).
• Zero close. NATR is undefined against a 0.0 close; the indicator reports 0.0 for that bar.
• Identity. NATR equals 100 · ATR / close bar for bar (natr_is_atr_over_close_as_percent pins this).
• Reset. natr.reset() clears the underlying ATR.

Examples

Rust

use wickra::{BatchExt, Candle, Indicator, Natr};

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut natr = Natr::new(14)?;
    let candles: Vec<Candle> = (0..40)
        .map(|i| {
            let p = 100.0 + f64::from(i);
            Candle::new(p, p + 2.0, p - 2.0, p, 10.0, i64::from(i)).unwrap()
        })
        .collect();
    let out = natr.batch(&candles);
    println!("warmup_period = {}", natr.warmup_period());
    println!("last = {:?}", out.last().unwrap());
    Ok(())
}

Python

import numpy as np
import wickra as ta

natr = ta.NATR(14)
high = np.arange(102.0, 142.0)
low = high - 4.0
close = high - 2.0
print(natr.batch(high, low, close)[-1])

Node

const ta = require('wickra');
const natr = new ta.NATR(14);
const high = Array.from({ length: 40 }, (_, i) => 102 + i);
const low = high.map((h) => h - 4);
const close = high.map((h) => h - 2);
console.log(natr.batch(high, low, close).at(-1));

Interpretation

Natr is the tool of choice whenever an ATR-based rule must work across instruments or across long stretches of time where the price level drifts. A volatility filter like "skip entries when NATR > 5" or a stop at "entry − 3 × NATR %" stays meaningful on any symbol. Use raw Atr only when you specifically want the answer in price units (e.g. to place a stop a fixed number of points away).

Common pitfalls

• Feeding it scalar prices. It needs high/low/close.
• Confusing it with ATR. NATR is a percentage; an ATR-multiple stop and a NATR-multiple stop are different distances.

References

NATR is the percentage-normalised ATR as implemented by TA-Lib (NATR); the underlying ATR is Wilder's from New Concepts in Technical Trading Systems (1978).

See also

• Indicator-Atr.md — the price-unit original.
• Indicator-HistoricalVolatility.md — return-based annualised volatility.
• Indicators-Overview.md — the full taxonomy.