Type a Hebrew word or a number. Every letter has a value; the calculator adds them, shows the working, and finds other words with the same total. Type in English and it converts the name first.
Shalom (376) equals Esau (376), a match the commentaries discuss. Chai (18) is why gifts come in multiples of 18.
Hebrew never had separate numerals. Letters did the job: alef to tet are 1 to 9, yod to tzadi are 10 to 90, kuf to tav are 100 to 400. A year like 5787 is written תשפ״ז, and a word like שלום is also a sum, 376.
Reading that sum against other words is the practice called gematria. The Talmud uses it to connect verses; the kabbalists built systems on it; and Israelis still use the everyday piece of it, which is why a wedding gift is 180 shekels and not 200.
Standard is the default everywhere. The large method gives the five final letters their own values, so a word ending in mem sofit jumps by 560. Ordinal counts position in the alphabet, which makes tav 22 rather than 400. Reduced folds every value to a single digit. Atbash reverses the alphabet before counting: alef reads as tav, bet as shin. Each is a different lens, and the calculator shows all five so you can see how a match holds up.