# How to determine a rat's age?



## Cara (Jul 5, 2017)

So, my partner and I have been trying to figure out how old our boys are. We got them three weeks ago and unfortunately, we got them from a pet shop and the pet shop people didn't know how old they were (I asked). We were guessing we got them around 10 weeks, making their birthdays around the end April and making them about 13 weeks now. When I first saw them (about 3 1/2 weeks before we got them), they were pretty tiny but seemed fully weaned and active and had all their fur and everything. We didn't have a battery for our food scale when we got them, or else I would have weighted them. Otherwise, their weights go like this:

Last Monday (10): Orion-254g, Houdini-220g

Tuesday (18): Orion-300g, Houdini-255g

Yes, Orion is going to be my fat little boy ;D (he was always the bigger one, even when we first got them)

I haven't measured them (I don't have a measuring tape) but is there any other way to determine a rat's age when they aren't fully grown yet? ???


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## Fu-Inle (Jan 22, 2015)

Hard to tell by weights because they vary alot and I have females and they tend to be smaller. Infact, I have fully grown females under 300 grams. 300g at 13 weeks sounds reasonable for a male rat but I have also heard of males reaching 300g by 9 weeks so it's hard to tell by weight alone because size and growth varies so much. My 12 week old female is 220g and I consider her bigger than average. Maybe if you could post a picture that might help.


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## Basiltheplant (Jan 2, 2017)

Fu-Inle said:


> Maybe if you could post a picture that might help.


I agree, I feel it would be easier to tell from a provided photo


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## TheBlizz (May 20, 2017)

Every individual rat grows at their own pace, and although their are averages, we can't be sure. The adult male rat weighs between 450 and 650 grams on average, according to the American Fancy Rat and Mouse Association (AFRMA). So, once your boys reach that range it is probably safe to assume they are full grown.

However, these are rough calculations and your boys may exceed them. Pictures would be helpful in this instance


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## Cara (Jul 5, 2017)

Here are some pictures. I tried to do the best I could but they weren't interested in staying still. Houdini is the Agouti in the first picture and Orion is the b&w variegated. Houdini is particularly difficult to get a picture of but I'm guessing they are about the same age.


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## Basiltheplant (Jan 2, 2017)

Pet stores typically sell pet rats starting at 3 months of age. So one method to find out a more specific age range is to ask the pet store when they first started selling that batch of rats. Looming at them, I would put them between 4-6 months


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## Fu-Inle (Jan 22, 2015)

I'm thinking they are around 3-4 months.


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