First off, here are their birth years: Bruce (1997), Dick (2012), Jason (2017), Tim (2020), and Damian (2028).

Bruce and Dick - 15 years (he's Bruce's bio kid, but neither of them actually know. Bruce just had some.. questionable coping mechanisms for an underage kid.)

Bruce and Jason - 20 years, was previously 22 I think? Fun fact, Jason was the longest standing Robin!

Dick and Jason - 5 years, was previously 7. Sometimes 2 depending on the run.

Jason and Tim - 3 years, Tim was 12 when Jason was 15 (aka when he was kidnapped by the Joker in this blog's canon)

Tim and Damian - 8 years. Jason had only been Robin for 2 years when Damian was conceived.

Additional Robin (+ Bruce) timeline:

Bruce became Batman when he was 23 (in 2020) and was 25 when he first adopted Dick (2022), for reference.

Dick was Robin for 3 years. He started at 10 instead of 8 (the most common canon age for his parents' deaths), because I love me some good father-son parallels and Bruce was 10 when HIS parents died.

Jason was Robin from the age of 8 to the age of 15 (when his death was initially faked and Tim replaced him), which is 7 years. He died at 17 (2034) because I've taken pieces of Arkham Knight Jason for his story (he was stuck with Joker for 2 years, not just 1.)

Tim became Robin in 2032, when he was 12, and stayed Robin until Damian came along! Tim was 17 (and has stayed 17 since lol). Which is five years (though Steph did have a little few-month-long Robin moment in the middle). He then became Red Robin, of course! Though he had his own abandonment issues crisis about being replaced by someone "better" than him. He'd just settled into the idea of Bruce actually caring about him, y'know? Only for that all to be ripped away. But that's something for another post!

Damian became Robin when he was 9, in 2037, when Bruce was 40. He's still the current Robin because I haven't really gotten past Bruce being 45 in this blog's canon yet! Hardly any plans for the future! But I do have a few possible storylines for Damian in his teen years going on.

Jason went back to Gotham just a few months before Damian turned up - He'd already had a bit of fun (beating up Tim) but hadn't gotten his full plans in action yet! When Jason and Damian meet as Red Hood and Robin for the first time, Jason actually lights up with recognition. They knew eachother for a few years, in the League! Jason was a bit of a father figure to Damian for those years. I think it's rather sweet!

Okay, so this post is....... A little messy. I just needed a place to put all of this! Hopefully I didn't fuck any maths up lol

Extras:

Bruce Wayne has OSDD-1B