Attention:

Certain features of sigmaaldrich.com will be down for maintenance Saturday afternoon/evening, February 24th starting at 3:00 pm CT until 9:00 pm CT.

Please note that you still have telephone and email access to our local offices. We apologize for any inconvenience.

Stable Isotopes

STP vs. NTP Gas Volume

ISOTEC® reports all gas volumes at Standard Temperature and Pressure (STP), while some suppliers quote their gas volumes at Normal Temperature and Pressure (NTP). One STP Liter is 7.7% more gas than one NTP Liter. Use this handy calculator to compare cost:

STP to NTP Cost Calculator
Enter Dollars per STP Liters
Enter Dollars per NTP Liters