Maintaining a Language While Learning a New One

You spent two years getting to B2 in Spanish. Now you want to learn Japanese. The question every learner avoids: how much Spanish do I have to keep doing to not lose it?

The honest answer: less than you think, but you can't skip it.

The 90-minute weekly rule

For a B2 language, 90 minutes per week of intentional practice is enough to maintain. Below that, slow erosion. Above that, slow gain.

That's 15-20 minutes daily, or one 90-minute weekend session, or two 45-minute weekday sessions. The total matters; the distribution can flex.

What counts as maintenance

• Reading a chapter of a book in target language
• One podcast episode
• One TV episode (with target subs)
• 30-min language exchange or tutor session

Note: passive consumption at this level largely counts. Once you've reached B2, your brain is already calibrated; maintenance is about not letting the calibration drift.

What doesn't count

• Music in the target language while doing other things
• Single-sentence exchanges
• Translation in your head (it's not target-language production)

Tracking the maintenance language

In your tracker, set a weekly target of 90 minutes for the maintained language. Don't try to grow it — just hit the floor.

Most weeks you'll easily hit it (a TV episode = ~45 min, two podcasts = ~60). Some weeks you'll under-deliver. After 3-4 weeks under, you'll feel the slip.

The compound interest of maintenance

Without maintenance:

• Year 1: maybe 80% retention
• Year 2: 60%
• Year 3: 40%
• Year 5: ~30%, but the foundation is still there

With 90 min/week:

• Indefinitely: ~95%, with the level slowly rising or falling within a CEFR band

That's a huge ROI for 90 minutes weekly.

The two-language sustainable pattern

If you're past B2 in language A and learning language B from scratch:

• Language A (maintenance): 90 min/week (~12% of time)
• Language B (active learning): 7+ hours/week (~88% of time)

This is sustainable for years. You hold A while building B.

What if I'm at B1, not B2?

B1 is fragile. You need 3-4 hours/week minimum for maintenance, not 90 min. Below that, you'll lose ground while learning the new language. Get to a confident B2 before adding anything.

For the next-level question, see maintaining multiple languages.