How much exercise for a 4 1/2 month old pup?

Our rescue GR pup is about 4 1/2 months old and I need to know how much exercise he should be having. I have read many articles about not exercising them too much but am unclear how much is too much as I am also aware that too little exercise is also bad for them. At the moment he has a walk in the morning of about 25 minutes of which 15 mins is spent off the lead and the rest of the time on a retractable lead. He has another walk of about 20 minutes in the afternoon where about 5 minutes is off lead and rest on a retractable. In the evening he has a 10 minute walk on a short lead to practice his lead skills. He also spends time playing in the house or garden at various times during the day. Have I got the exercise right or is he doing too much or too little and at what age should I start taking him for long walks. We have no idea where he was bred so have no details of parents hip scores and we SO do not want to get this wrong. Any help would be greatly appreciated. What age does he stop being considered a puppy?

Hi Lizzie It is important not to over exercise puppies the reason being you do not want to strain growing joints. The rule for lead walking is five minutes for every month of life total per day and I think walking on soft ground like grass is best some of the time if you can manage it . Casual exercise like running around in the garden is slightly different because the puppy can go at his own pace and stop when tired.

Thank you for your reply - I will cut down on the walks then and only let him off lead for 5 minutes. I usually walk him at the woods or on the beach having driven him there in the car as he wasn't so good at travelling in the car to begin with - lots of barking - but has settled down since he got the reward of a walk at the end of the trip!

You have been given good advice, just to add avoid steps and stairs and jumping on furniture or into or out of the car.

We live in a bungalow so don't have any stairs to climb. What age can he jump out of the car as he is already getting quite heavy to lift in and out and being only 5 feet tall I soon won't be able to lift him anymore?He isn't allowed on the furniture so that isn't a problem.

Lizzie, there is the ideal way to deal with dogs and there is the possible, so if you can't lift him in and out of a car and you don't have a ramp you have to let him jump in and out, however you know there is a risk so you will keep it to the minimum and try to make him do it in a calm and careful manner. When asked we give advice but rules and advice have to be bent round what is possible.

Re jumping out of the car - can you put something soft down to absorb some of the impact?

Thanks for advice - getting in the car is not such a problem as he puts his front feet on the bumper and I can carefully lift him in but it is the getting out when he jumps. I am careful what he is landing on - usually mud in the woods! - and it is a controlled jump not a mad rush for freedom so hopefully he will be OK.
I only let him off lead for 5 minutes this morning but he does "mad running" for most of this time - any ideas how to stop this or is it ok - he really enjoys himself and I would hate to not be able to let him off at all -also helps with his recall training.

Usually free exercise is ok as the pup will stop when they have had enough but it can be a problem if another dog is present especially if that dog is large of heavy because the pup will get excited and over do the rushing about and may get bowled over by the other dog.