What is the recommended minimum key length for ECDSA signature

I want to identify the proportion of certificates that use unrecommend ECDSA key length for TLS certificates based on some data I collected.

By looking at a standard like NIST for example, I find this in this website:

My data shows use of ecdsa-with-SHA256.

My question is: Which if the following key algorithms the ECDSA is based on? Since ECDSA stands for (Elliptic Curve Digital Signature Algorithm) my understanding is that it is based on Elliptic Curve. So since we are in 2018/2019, I assume the recommended length is 224 bits?

• The recommended key size for ECDSA changes according to usage, see Table 2-1 at NIST 800-57 – kelalaka Dec 16 '18 at 15:35
• @kelalaka thanks for the additional reference. But in my post, I should look for Elliptic-Curve bits if the key is ECDSA? – user9371654 Dec 16 '18 at 20:24
• Yes, you should, of course. – Maarten Bodewes Dec 17 '18 at 0:13