I found out that one question is very common in Czech research: "I found a marriage/death record of my ancestor and when I looked for his birth record, I found one, but the age counted from that birth record is different from the one shown in the marriage/death record. Is it really my ancestor's birth?" Let's take a look on such issues...
When someone asks you "how old are you?" or "when were you born?", it's natural for you to know the answer, right?
But it was not natural for our ancestors some two hundred years ago. Years weren't important for them. They lived a cyclic style of life - it was the same every year, beginning with spring seeding to summer and harvest, then autumn, Christmas and winter. All the same whole their life. Often every year the same as the previous one. They were not forced to count the years as it was not important for their career or school or anything else.
Illustration from Strakonice death registry - I just had to use it somewhere... :)
So - they didn't remember how old they were or when exactly they were born. They knew in which part of year they were born - often thanks to their Christian name as they were given the name of the saint whose feast was near to their birth (ie. Václav's were often born in September - I think I'll write a separate post about it). But they rarely knew how old they exactly were.
They for example remembered they were born during the reign of Emperor Josef II. - but he reigned for 10 years, so there was ten years span. Or worse - they remembered that the Queen Marie Terezie was reigning when they were born. But she reigned for 40 years!
Marriage registries often show discrepancy of 2, 3 or 5 years - it's nothing strange. It sometimes happens that if there is large difference between age of groom and bride (for example 65 years old widower married 22 years old girl) the age was adjusted to hide that huge difference (50 yo + 28 yo).
Death registries are even more wrong. As the person got older, the estimated age was more and more inaccurate. If someone was the oldest person from the village when he died, it was often claimed he was 100 years old - because no one remembered the time when he was born or young.
Information about age was often provided by the family - the priest who wrote down the age to the marriage or death registry didn't check this information in the birth registry too often. Of course there were priests who checked this information, but there were not too many of them in the past. And of course - the family didn't know exact age. That's why the age in death registries is often round-up to fives or tens (50, 55, 60, 65 etc.).
So - if there is just five years discrepancy between the age in death registry and that counted from the birth recor, it's nothing strange and unusual. I even found records where the discrepancy was around 30 years. It just happens... Age was not important to our ancestors - and this is what happens in such cases.