I'm not sure if somewhere a similar English site is available but you can just try this German ones:
https://hilfsmittel.gkv-spitzenverband. ... ntergruppeThis is a database where all medical aids are listed that are generally available over the public health system. If yo go to "saugende Inkontinenzhosen" you will find diapers listed by incontinece level. If you go to "saugende Inkontinenzvorlagen" you will find pads.
For the Tena Pants you will find then a record like this (
https://hilfsmittel.gkv-spitzenverband. ... ktId=45158):
Inkontinenzunterhose mit erhöhter Saugleistung
- Flüssigkeitsaufnahme: 845,63 g
- Aufsauggeschwindigkeit: 6,47 ml/s
- Flüssigkeitsabgabe: 0,06 g
- ABL-Wert gemäß DIN 13222: 322,0 g
- Umfanggröße nach Herstellerangaben: ca. 95 cm bis 125 cm
The most relevant value is the ABL-Value what means "Absorption Before Leakage". This is a good starting point to compare products. The "g" for gramm equals "ml" for Milliliter here because urine have nearly the wight of water.
The database covers of cause products available in Germany but you will find most large international brands there. Of cause it is not guaranteed that the North American products have the same quality but it is a starting point. For Germany the vendors where urged to publish the data because otherwise they are excluded from the list. So it is not 100% clear if the products in other countries are really comparable.