There are different ways of converting weight, length, volume etc.
metric
You use conversion factors.
It is a customary unit.
The opposing systems are imperial and metric, not customary. But, meters are metric.
The pound is NOT a metric unit.
Yes, there is a site called science made simple online that allows you to convert from the metric system for your recipe. It has a detailed chart that you can easily follow.
It is customary.
It can be more or less. An once (customary) is bigger than a gram (metric) but a pound (customary) is smaller than a kilogram (metric).
Metric.
Metric.
Metric
It is a customary unit.