I don't have benchmark info, but I can tell you what we do if that helps.

We are an Ed tech business (elearning) and give a half day per quarter, but you can round it up so 2 days per year. There are a couple of restrictions on what you can use it for, no golf days(!), nothing that is connected to specific political groups (eg campaigning, but could help at a polling station), same for religious organisations, no competitors and you can't get paid. Pretty much everything else is ok - PTAs, Citizens advice, phone support lines, animal walking etc. Take up is low, out of 200 odd staff I think only about 5 actually use them, despite my constant reminders to people they are available.

We're a group of museums and we offer up to 2 volunteering days per year - either for Trusteeships of other Arts organisations, school governorships, or volunteering for other national or local charities.  Like Elsa, we have very few people who take advantage of them, despite reminders.

We offer 2 days a year to all colleagues. Take up is mixed. Generally, people use them for things they were doing anyway. Although some teams have done team based volunteering projects which is pretty cool

We offer up to 4 days volunteering per year matched with the same time taken as annual leave. 

In reply to Elsa Knight:

Thanks Elsa, that is really helpful. I was thinking of offering 3 full days for full-time staff, but I like your idea of giving them per quarter.

Do you prorate for part-time staff?

In reply to Jacqueline:

Thanks so much, I think I am doing my own benchmarking here :)

Take up does seem to be a consistent theme, from what I have been reading where an organisation partners up with a charity or community group and offers opportunities, there tends to be better take up, but I don't think this little start-up has this capacity yet!

In reply to Keith:

Allowing teams to organise a group volunteering project seems like a really good idea.... (adds into policy)  thanks :)

In reply to Helen:

Super thanks for sharing Helen

In reply to Sarah Sutton:

You're welcome.

No, we don't prorate, but we don't have many part timers and take up is so low it doesn't seem worth it.

As Keith said, take up is usually by people who were already volunteering, rather than people doing new things. We planned to arrange some group activities (employee led) and I looked at a local organisation who matches volunteers with organisations who need help but Covid stopped a lot of our plans and now changes to the business have left me thin on time to get it going again.

It also seems to go down well with candidates when I tell them it's part of our paid time off package - even if they don't go on to use it