To answer this question, we need to clarify a concept here. The max working pressure of a pressure cooker is the pressure which pushes up the safety device (i.e. steam release, pressure valve or by some other names) and the cooker starts letting out steams to reduce pressure. The max working pressure of stove-top pressure cookers ranges from 12psi to 21.7psi. For the high-end stove-top models, it is typically in the 16~21.7psi range. This is specified in product document and also commonly marked at the bottom of the steam release.
Instant Pot has a max working pressure of 15.23psi (105kpa). This is marked on the steam release handle, see the image on the top. One of the design objectives of Instant Pot is not to let out steam and make noise during its operation. So normal working pressure has to be below 15.23psi. Instant Pot’s working pressure is in the range of 10.15~11.6 psi. If you have small amount of food/liquid in the cooker, Instant Pot may touch 15.23psi momentarily due to the heat conduction delay.
When a stove-top pressure cooker reaches its max working pressure and starts whistling out steams, you’d turn down the heating to stop the whistling. In such a condition, your stove-top pressure cooker may be operating at a pressure level similar to Instant Pot. You only cook the food at the max working pressure when it’s whistling continuously.
- Does Instant Pot have the same 15 psi max working pressure as common stove-top pressure cookers? Yes! It’s 15.23psi.
- Does Instant Pot cook your food constantly at 15psi? No, it’s in the range of 10.15~11.6 psi.
You can see the working pressure chart on the right. Most electric pressure cookers available on the market work like this, but may not have the same max and working pressure range.
If your recipe specifies cooking at 15psi, you can adapted to Instant Pot by increasing the cooking time by 7~15%.
Note: the max working pressure is not an indicator of the max safety pressure that the cooker can withstand. If a cooker is certified with UL or equivalent, it should withstand 5 times the working pressure without leaking.
Many electric pressure cooker has a max working pressure of 13.05psi (90kpa). You can find this out by looking at the bottom of its steam release. A properly certified and manufactured cooker always has such rating on the parts.