Emissions measure the amount of Carbon Dioxyde CO2 that is being introduced into the atmosphere and are thus expressed in tons of CO2 equivalent per year tCO2e/y.
Sequestration on the other hand concerns itself with how much Carbon C is being removed from the atmosphere and then stored, and is expressed in tons of Carbon Equivalent per year tCE/y.
In order to determine how many hectares of Mangroves you will need to restore in order to completely offset you emissions, you will thus need to first convert CO2e into CE and then, to convert that result into hectares of Mangroves.
Because of its two additional molecules of Oxygen, CO2 has a greater mass (44) than simple Carbon (12).
With that in mind, the conversion between CO2e and CE is directly related to the ratio of the atomic mass of a carbon dioxide molecule to the atomic mass of a carbon atom (44:12).
To convert from CE to CO2e, multiply by 44/12
1 metric ton carbon equivalent = 3.667 metric tons of CO2 equivalent.
To convert from CO2e to CE, multiply by 12/44
1 metric ton of CO2 equivalent = 0.2727 metric tons of carbon equivalent.
Assuming that one hectare of Mangroves sequester one metric ton of Carbon per year: to convert your Carbon Footprint into hectares of Mangroves, multiply by 0.2727 and round up to the next hectare.
Do not forget to then add the area corresponding to your Physical Footprint!