Impedance Calculator, Coplanar or non-coplanar

Dear JLCPCB Engineer,

Some of my PCB designs involve high-frequency signals and require traces with specific characteristic impedance, usually 50 ohms. I noticed that JLCPCB provides an Impedance Calculator. For most of my designs, I use:

- Double layers

- Standard thickness of 1.6mm and 1 oz copper

- Both bottom and top layers poured with ground plane

I understand that:

- If the signal trace is on the top layer with a ground plane on the bottom layer, I should use the "non-coplanar single-ended" calculator.

- If the signal trace and ground plane are on the same layer, with no ground plane on the other layer, I should use the "coplanar single-ended" calculator.

However, if I use ground planes on both layers, which calculator should I use?

Attached are pictures from the JLCPCB calculator and my illustration for reference.

I appreciate your assistance.

Regards,

Mula