Every interval timer asks for the same three numbers: how long to work, how long to rest, and how many rounds. The right answer depends on what you want from the session. A sprinter and a person trying to lose weight should not be using the same settings, even if they do the same exercises. This guide gives recommended settings for six common goals, explains the reasoning, and ends with a table you can copy straight into the interval timer.
The three levers
- Work time sets what kind of effort you can produce. Ten seconds allows a flat-out sprint. Three minutes forces a pace you can hold for three minutes, which is much lower.
- Rest time sets how recovered you are at the start of the next interval. Long rest means high-quality repeats. Short rest means a high heart rate for the whole session and declining output.
- Rounds set the total work volume. Multiply rounds by work time to get total hard minutes, which is the number that matters most for comparing sessions.
Decide what you want the session to do first, then set the levers. The interval ratios guide covers the ratios themselves in more detail.
Goal 1: conditioning and work capacity
Settings: work 40, rest 20, rounds 15 to 20. Session: 15 to 20 minutes.
Conditioning means being able to keep working at a decent pace while tired. The 2:1 ratio gives you enough rest to keep moving well but not enough to fully recover, so the fatigue builds across rounds. Choose full-body movements that let you shift between muscle groups: kettlebell swings, rowing, burpees, medicine ball slams. Once 20 rounds feels manageable, tighten the ratio to 45/15 using the 45/15 timer rather than adding more rounds.
Goal 2: fat loss and general fitness
Settings: work 30, rest 30, rounds 16 to 20. Session: 16 to 20 minutes.
For general fitness, the most important thing is doing the session regularly for months, not making any single workout brutal. A 1:1 ratio is sustainable, lets you use a wide range of exercises with good form, and leaves you able to train again two days later. Total weekly activity matters here more than any single setting: the WHO's 2020 guidelines suggest 150 to 300 minutes of moderate or 75 to 150 minutes of vigorous activity a week, so three 20-minute interval sessions plus walking on the other days is a realistic structure. No interval setting makes up for a diet that does not match the goal.
Goal 3: strength endurance
Settings: work 45, rest 45, rounds 10 to 12. Session: 15 to 18 minutes.
Strength endurance is the ability to keep producing force over many reps: carrying, climbing, rowing, manual work. Use loaded movements such as goblet squats, push-ups, dumbbell rows, weighted step-ups and farmer's carries, at a weight that lets you work for the full 45 seconds without stopping. The equal rest lets your muscles recover enough that the reps stay clean. If form breaks in the last 10 seconds of the work interval, lighten the load, not the time. EMOM format also suits this goal well; see EMOM workouts.
Goal 4: running speed
Settings: work 20, rest 100, rounds 8 to 10. Session: 16 to 20 minutes plus warm-up.
Speed needs quality, and quality needs rest. With 20 seconds of fast running and well over a minute of walking or very easy jogging, each repeat can be as fast as the first. If the rest feels too long, you are not running the work interval fast enough. Short rest here is counterproductive: tired sprinting teaches slow, sloppy running mechanics. For longer speed-endurance work, 60/60 for 8 to 12 rounds is a good second session. Running intervals has a full set of sessions by level.
Goal 5: boxing and martial arts
Settings: work 180, rest 60, rounds 5 to 8. Session: 20 to 32 minutes.
Fighters should train on the clock they compete on. Three-minute rounds with one minute of rest mirror professional boxing, and the same timing suits Muay Thai and kickboxing bag work. The round length teaches pacing: you learn to work in bursts, recover while still moving, and finish each round strongly. Newer trainees can start with 2-minute rounds (work 120, rest 60) and build up. The boxing timer is preset to 3/1 with twelve rounds; lower the rounds for a training session.
Goal 6: complete beginners
Settings: work 30, rest 60, rounds 8. Session: 12 minutes.
When you are new, the goal is to learn the rhythm of intervals and recover between sessions, not to test yourself. A 1:2 ratio gives plenty of recovery, so you can hold a moderate effort in every round. After two weeks, move to 30/45, then 30/30. Changing one variable at a time, rest first, then rounds, then work time, keeps progress steady and avoids the sore, discouraged week that ends most beginners' attempts.
Summary table
| Goal | Work (s) | Rest (s) | Rounds | Session | Timer |
|---|---|---|---|---|---|
| Conditioning | 40 | 20 | 15 to 20 | 15 to 20 min | Interval timer (default 40/20) |
| Fat loss / general fitness | 30 | 30 | 16 to 20 | 16 to 20 min | 30/30 timer |
| Strength endurance | 45 | 45 | 10 to 12 | 15 to 18 min | Interval timer |
| Running speed | 20 | 100 | 8 to 10 | 16 to 20 min | Interval timer |
| Boxing / martial arts | 180 | 60 | 5 to 8 | 20 to 32 min | Boxing timer |
| Beginners | 30 | 60 | 8 | 12 min | Interval timer |
Adjusting the settings
- Finishing every round strong? Cut rest by 10 seconds or add two rounds, not both.
- Output collapsing by the halfway point? Add rest or reduce rounds. Fading is a sign the ratio is too tight for your current fitness, not that you need to try harder.
- Running out of session time? Keep the work and rest the same and drop rounds. Fewer rounds at the right intensity beat a full set at the wrong one.
- Not sure? Start with the 30/30 setting for 12 rounds. It is hard to get badly wrong, and after two sessions you will know which direction to move.
Whatever you choose, warm up for 5 minutes first and write the settings down. A session you can repeat exactly next week is a session you can measure progress against.