Twenty new words a day sounds like a good plan. It is also the plan most people abandon within a month. Not because twenty is too many to learn, but because of what those twenty words turn into a few weeks later.
The right daily number depends less on how fast you can learn and more on how many reviews you can keep doing. Here is how to work it out.
The hidden cost: reviews pile up
A word learned once is mostly forgotten within a day or two. To keep it, you meet it again on a widening schedule, say after one day, three days, a week, two weeks and a month. That is five reviews for every new word.
Now do the arithmetic for a steady pace:
| New words a day | Words in review at once | Reviews a day, after a month |
|---|---|---|
| 5 | about 150 | about 25 |
| 10 | about 300 | about 50 |
| 20 | about 600 | about 100 |
| 30 | about 900 | about 150 |
After a month, every day brings its new words plus the reviews of every word from the last few weeks. At 20 new words a day, that is around a hundred reviews daily, every day, before the new ones. Words you get wrong come back sooner, so the real number is higher.
That is what people quit. The new words were never the problem.
Work backwards from your goal
Pick what you want and a date, then divide.
- One level up in a year. Moving from B1 to B2, or B2 to C1, is roughly 500–1,000 words (Milton and Alexiou, 2009, measured learners at each level). That is two or three new words a day. It sounds slow and it is enough.
- An exam in six months. An academic word list for IELTS or TOEFL is several hundred words. Five to ten a day covers one with room for review.
- Reading novels without a dictionary. Comfortable reading takes around 8,000 word families (Laufer and Ravenhorst-Kalovski, 2010). From B1, that is years at ten a day, and it is why reading itself, not lists, does most of the work at that stage.
For comparison: native speakers keep learning into old age, at about one new word every two days between 20 and 60 (Brysbaert and colleagues, 2016). Adult vocabulary grows slowly even for people surrounded by the language.
A sensible default
Five to ten new words a day suits most adult learners who have ten or fifteen minutes. It keeps the review load under fifty a day, which is a few minutes if each review is quick, and it adds up to around 1,800–3,600 words a year, a level or more.
Go lower if you keep missing days. A pace you can hold for a year beats one you hold for three weeks. Go higher only if the reviews stay easy.
Signs your pace is wrong
- You are skipping reviews to get to new words. You are learning faster than you are keeping. Drop the new words for a few days and clear the pile.
- Reviewed words feel brand new. The gaps are too long or the words are too far above your level. Pick easier words or review sooner.
- Everything feels easy. Raise the number, or move up a level.
Short sessions beat long ones
Ten words in one sitting is harder to keep than the same ten met separately through the day. Spacing works at every scale: seeing a word in the morning, again at lunch and again in the evening does more than three looks in a row.
That is the case for learning in the gaps of the day, a minute on the bus, a glance at your phone, rather than one long session you have to find time for.
What I am building for this
I am building an iPhone app, VocabPeek, that does the pacing on your Lock Screen and Home Screen. You choose how often the word changes, from every 30 minutes to every six hours, and the app tells you what that means: changing every hour brings about eleven new words a day, with every third slot kept for a word due for review. When reviews pile up, it shows more of them and fewer new words until the pile is down, so the load never runs away from you. By default it rests overnight, from 11 pm to 7 am.
It is not on the App Store yet, and it has no release date.
Short answers
How many new English words should I learn a day? Five to ten suits most adults. More than that and the reviews, not the new words, become the limit.
Is 20 words a day too many? It is possible, but after a month it means around a hundred reviews a day. Most people stop long before that.
How many words can you learn in a year? At ten words a day with regular reviews, around 3,000 on paper, fewer once some are forgotten. That is still more than one CEFR level’s worth.
Should I learn words in one session or through the day? Through the day. Several short meetings with a word beat one long session.