Exodus 12:40 -- The Hebrews lived for 430 years in Egypt.
Acts 7:6 -- The Hebrews lived for 400 years in Egypt.
The Scriptures given in the above statement of the problem with references regarding the 430 and the 400 years duration of the stay of the Hebrews in Egypt must be compared with some other scriptures about the same topic and time period. The mention or assumption that the Hebrews lived either 430 or 400 years in Egypt is in itself already incorrect as this study will show. This is only a very widespread assumption which is based on a rather cursory reading of the relevant scriptures as well as a rather incorrect translation from the old texts.
An important and very helpful statement for determining the time frame in general is found in Galatians 3:15-17, where it is said that the Law (the giving of the Law at Sinai by Moses) was 430 years after the promise to Abraham. The whole time therefore between God's promise to Abraham and the time when Israel received the Law was 430 years.
The Law was given in the same year that Israel left Egypt, a short time after they had crossed the Red Sea and were camping near Mt. Sinai (cp. Exodus 19). This now poses the question as to how Israel (the Hebrews) could have lived in Egypt for 400 or 430 years when the whole time between the promise to Abraham in Ud in Chaldaea until the year of the exodus from Egypt was only a total of 430 years. In what has been just noted, a very important key to finding the solution is given: The time periods of the 430 years between Abraham and the Law and the 400 or 430 years of the supposed stay of the Hebrews in Egypt end in the same year.
A verse in Acts 7:6 has reference to Genesis 15:13-14 where God told Abraham that his descendants "shall be a stranger in a land that is not theirs " for a period of four hundred years. The following points must be noted: (1) The statement is regarding Abraham's SEED (his descendants). (2) The time period of 400 years includes the time in which they would be strangers in a foreign land and it not only refers to a time in Egypt. Abraham himself is excluded because the verse speaks of his seed, specifically those descendants who are of the line promised to Abraham, i.e. Isaac, Jacob and his sons.
In Exodus 12:40 however, 430 years are mentioned during which Israel (the Hebrews) were sojourning in land which was not their own. The important point to note here is thatAbraham as the forefather of the Hebrews (Israel) is included and that this reference concerns not only his seed. The two time periods of 400 and 430 years of sojourning or being strangers also end in the same year, the year when the Law was given at Sinai. This means that Isaac (Abraham's seed) therefore was born 30 years after the initial promise was made to Abraham. Abraham left Haran after the death of his father Terach at the age of 75, Isaac was born when Abraham was 100 years old, and (according to Acts 7:2) God already appeared to Abraham when he was still in Ur of the Chaldeas, it is clear that Abraham received God's promise at the age of 70 which was also then the time when he left from Ur in order to sojourn as a stranger in a foreign land as God had told him to do.
Some difficulties are still posed by remarks such as: " That his seed should sojourn in a strange land; and that they should bring them into bondage, and entreat them evil four hundred years." (Acts 7:6), and " thy seed shall be a stranger in a land that is not theirs, and shall serve them; and they shall afflict them four hundred years" (Genesis 15:13). In both cases there is a parenthesis in each verse which has not been noted, and which will clarify the meaning of the text quickly. They should read as follows: " That his seed should sojourn in a strange land and that they should bring them into bondage, and entreat them evil four hundred years." (Acts 7:6), and " thy seed shall be a stranger in a land that is not theirs and shall serve them; and they shall afflict them four hundred years" (Genesis 15:13). The statement in Exodus 12:40 also has this parenthetical remark: Now the sojourning of the children of Israel -- who dwelt in Egypt -- was four hundred and thirty years.
Israel (the Hebrews) were not 400 nor 430 years in Egypt, they did not even spend the whole time of their time in Egypt in bondage. When reading about Abraham, Isaac and Jacob it is easily recognized that only Jacob in relatively old age went down to Egypt with his descendants after his son Joseph had risen to a high position at the court of Pharaoh. The time before this, approximately half of the 430 years, the Hebrews lived as sojourners in the land of Canaan. The first part of their time in Egypt they spend there in freedom and under the protection of Pharaoh. Only some time after Joseph's death when a foreign dynasty took over the rule in Egypt the servitude of Israel in Egypt started (cp. Exodus 1).
Another reference which confirms these time references is found in Genesis 15:14-16, where God promised Abraham that his seed who would go down to Egypt would return from Egypt in the 4th generation. This is exactly what happened. Levi, Jacobs son went with Jacob into Egypt, the next generation after Levi was his son Kehat, after that came Amram, and the fourth generation then was Moses under whoe leadership Israel then left Egypt.