CO2 neutralizing shipments - calculator?

[Martin F]

Hi all,

We're considering to "CO2 neutralize/compensate" all our order shipments as part of a set of sustainability initiatives.
While we naturally realize that this doesn't make the CO2 emissions disappear, we figure it would be better than not doing any offsetting.

However, I've looked for quite a while to find any framework/methodology/calculators to help set this up in a semi-formal way.

Do any of you know of others that have done something similar - and how it's been set up?
And do you know of any sources regarding how much the CO2 emission would be for a basic parcel (FedEx envelope) being shipped from X to Y and weighing Z kg?

Thanks for your inputs,
Martin