Couldn't find a ncs to hex (or ncs to anything) color converter in PHP, so I translated the convert function from https://github.com/m90/ncs-color to PHP.

NCS to HEX color conversion

<?php

//Eats NCS S 3010-G20Y and puts out #a8bca0
function ncs2hex($ncs) {

		$ncs = trim($ncs);
		$ncs = strtoupper($ncs);
		$ncs = preg_match("/^(?:NCS|NCS\sS)\s(\d{2})(\d{2})-(N|R|G|B|Y)(\d{2})?(R|G|B|Y)?$/", $ncs, $output_array);
		$ncs = $output_array;

		$Sn = intval($ncs[1]);
		$Cn = intval($ncs[2]);
		$C1 = $ncs[3];
		$N = intval($ncs[4]);
		$Ra = null;
		$x1 = null;
		$Ba = null;
		$x2 = null;
		$x3 = null;
		$x5 = null;
		$Ga = null;
		$x6 = null;
		$x7 = null;
		$x8 = null;
		$Rc = null;
		$Gc = null;
		$Bc = null;
		$top = null;
		$ss = null;

		if ($C1 !== 'N') {

			$S = (1.05 * $Sn - 5.25);
			$C = $Cn;
			$Cx = $Cn < 10 ? '0'+$Cn : $Cn;

			// extract red
			if ($C1 === 'Y' && $N <= 60) {
				$Ra = 1;
			} else if (($C1 === 'Y' && $N > 60) || ($C1 === 'R' && $N <= 80)) {
				if ($C1 === 'Y') {
					$x1 = $N - 60;
				} else {
					$x1 = $N + 40;
				}
				$Ra = ((sqrt(14884 - pow($x1, 2))) - 22) / 100;
			} else if (($C1 === 'R' && $N > 80) || ($C1 === 'B')) {
				$Ra = 0;
			} else if ($C1 === 'G') {
				$x1 = ($N - 170);
				$Ra = ((sqrt(33800 - pow($x1, 2))) - 70) / 100;
			}

			// ext$ract blue
			if ($C1 === 'Y' && $N <= 80) {
				$Ba = 0;
			} else if (($C1 === 'Y' && $N > 80) || ($C1 === 'R' && $N <= 60)) {
				if ($C1 === 'Y') {
					$x2 = ($N - 80) + 20.5;
				} else {
					$x2 = ($N + 20) + 20.5;
				}
				$Ba = (104 - (sqrt(11236 - pow($x2, 2)))) / 100;
			} else if (($C1 === 'R' && $N > 60) || ($C1 === 'B' && $N <= 80)) {
				if ($C1 === 'R') {
					$x3 = ($N - 60) - 60;
				} else {
					$x3 = ($N + 40) - 60;
				}
				$Ba = ((sqrt(10000 - pow($x3, 2))) - 10) / 100;
			} else if (($C1 === 'B' && $N > 80) || ($C1 === 'G' && $N <= 40)) {
				if ($C1 === 'B') {
					$x5 = ($N - 80) - 131;
				} else {
					$x5 = ($N + 20) - 131;
				}
				$Ba = (122 - (sqrt(19881 - pow($x5, 2)))) / 100;
			} else if ($C1 === 'G' && $N > 40) {
				$Ba = 0;
			}

			// exct$ract green
			if ($C1 === 'Y') {
				$Ga = (85 - 17 / 20 * $N) / 100;
			} else if ($C1 === 'R' && $N <= 60) {
				$Ga = 0;
			} else if ($C1 === 'R' && $N > 60) {
				$x6 = ($N - 60) + 35;
				$Ga = (67.5 - (sqrt(5776 - pow($x6, 2)))) / 100;
			} else if ($C1 === 'B' && $N <= 60) {
				$x8 = (1 * $N - 68.5);
				$Ga = (6.5 + (sqrt(7044.5 - pow($x8, 2)))) / 100;
			} else if (($C1 === 'B' && $N > 60) || ($C1 === 'G' && $N <= 60)) {
				$Ga = 0.9;
			} else if ($C1 === 'G' && $N > 60) {
				$x7 = ($N - 60);
				$Ga = (90 - (1 / 8 * x7)) / 100;
			}

			// ext$ract satu$ration
			$x2 = ($Ra + $Ga + $Ba) / 3;
			$Rc = (($x2 - $Ra) * (100 - $C) / 100) + $Ra;
			$Gc = (($x2 - $Ga) * (100 - $C) / 100) + $Ga;
			$Bc = (($x2 - $Ba) * (100 - $C) / 100) + $Ba;

			// ext$ract blackness
			if ($Rc > $Gc && $Rc > $Bc) {
				$top = $Rc;
			} else if ($Gc > $Rc && $Gc > $Bc) {
				$top = $Gc;
			} else if ($Bc > $Rc && $Bc > $Gc) {
				$top = $Bc;
			} else {
				$top = ($Rc + $Gc + $Bc) / 3;
			}

			$ss = 1 / $top;

			$rgb = [
				"R" => intval(($Rc * $ss * (100 - $S) / 100) * 255),
				"G" => intval(($Gc * $ss * (100 - $S) / 100) * 255),
				"B" => intval(($Bc * $ss * (100 - $S) / 100) * 255),
			];

		} else {

			$v = intval((1 - $Sn / 100) * 255);
			$rgb = [
				"R" => $v,
				"G" => $v,
				"B" => $v,
			];

		}

		return sprintf("#%02x%02x%02x", $rgb['R'], $rgb['G'], $rgb['B']); // #0d00ff

	}