If you calculate that with the currently most commonly used flat rate of 650 euros, you have only insured about 100 sqm, while insured 155 sqm. Something is at least inconsistent there.
.. as a rule, you usually do not have to specify a sum but the number of square meters to be considered when insuring your household contents with a waiver of underinsurance. A flat rate per square meter is then applied, which adjusts from year to year according to price indices, etc.