Picking an interval timer comes down to two questions: where are you going to use it, and how complicated do your intervals need to be? Gymboss makes four models — Classic, Plus, Charge, and miniMAX — and the right one depends entirely on those two answers, not on which model is newest or most expensive.

What does an interval timer actually do?

An interval timer counts down a set period of time, alerts you with a beep or vibration when it’s up, and then starts the next interval automatically — repeating the cycle as many times as you’ve programmed. Instead of watching a stopwatch and guessing when 30 seconds have passed, the timer handles the counting so you can focus on the work or rest period itself. This is why interval timers show up across so many different activities: running intervals, HIIT circuits, rest periods between weightlifting sets, Pilates sequences, and even non-fitness uses like cooking multiple dishes at once.

Gymboss Classic: best for simple indoor intervals

The Classic times one or two intervals and repeats or cycles through them. That’s the whole feature set, and for a lot of training styles, it’s all you need. If your workout structure is “30 seconds on, 30 seconds off” or “lift, then rest a fixed amount of time before the next set,” the Classic handles it without any extra complexity. It’s designed for indoor use — think a Tabata session, an interval running workout on a treadmill, or timing rest between weightlifting sets at the gym.

Gymboss Plus: best for runners and outdoor use

The Plus has the exact same interval functionality as the Classic — one or two intervals, repeat or cycle — but with a louder beep and more water resistance. That combination makes it the better pick for outdoor training, especially running in the rain or in humid climates where the Classic’s quieter beep and lower water resistance would be a limitation. If you run outside regularly, the Plus is the more practical choice over the Classic even though the underlying timing function is identical.

Gymboss Charge: best for the loudest alarm and rechargeable power, and runners and outdoor use

The Charge matches the Classic and Plus on functionality but stands apart in two ways: it has the loudest alarm of all four models, and it runs on an internal rechargeable battery instead of the single AAA battery the other models use. If you’ve ever missed a beep in a loud gym or on a noisy street the Charge solves this problem.

Gymboss miniMAX: best for complex HIIT programs

The miniMAX is built for a different level of complexity. It can time up to 25 different intervals in a single sequence and lets you repeat individual intervals or entire groups of intervals within that sequence — something none of the other three models can do. It also saves up to 20 programs for future use, so an advanced HIIT routine with many different interval lengths only needs to be programmed once. The Classic and Plus can’t save programs, which makes the miniMAX the clear choice if you run varied or advanced interval programs regularly rather than the same one or two intervals on a regular basis.

Are Gymboss timers waterproof?

No Gymboss model is waterproof, and none should be submerged in water. The Plus and Charge are water and sweat resistant, which makes them suitable for outdoor use like running in the rain, but “water resistant” is not the same as “waterproof.” 

Quick decision guide

• Indoor training, simple intervals (lifting, HIIT or Tabata): Classic
• Outdoor running, rain, or humidity: Plus
• Need the loudest alarm, outdoor running or want to skip batteries: Charge
• Advanced HIIT with many different interval lengths, want to save programs: miniMAX

Frequently asked questions

Can the Classic, Plus or Charge save programs? No — saving programs is exclusive to the miniMAX, which can store up to 20 programs. The Classic, Charge and Plus will always default to the last program used.

Does the miniMAX lose saved programs if the battery dies or it reboots? No, saved programs are retained through a battery change or reboot.

Will a Gymboss Watchstrap work with any model? Yes, the Watchstrap is compatible with all four current models: Classic, Plus, Charge, and miniMAX.

What’s the Gymboss warranty? A 30-day money-back guarantee plus a 1-year warranty against manufacturing defects, detailed under the Gymboss Guarantee on the Returns page.