Reformer Springs Explained: What the Colors Mean and How to Choose

Reformer springs set the resistance on the carriage, and the colors tell you how strong each spring is. But the colors only mean something on the machine in front of you, because every manufacturer uses its own code. A red spring is the medium one on a Balanced Body reformer and the heavy one on a Merrithew, Peak or BASI machine. So the honest answer to "what spring should I use?" is to learn how springs behave rather than memorizing a color. And whatever instinct you walked in with, heavier does not mean harder.

In my studio, spring settings are the question I hear most, usually from people whose old setting suddenly feels wrong on our machines. Here is what I tell them.

Why the Colors Change From Studio to Studio

No industry-wide color standard exists. Each brand picks its own colors and its own tension steps, and the springs are not interchangeable either: the Pilates Anytime help center notes that springs made by one manufacturer are not compatible with another brand's reformer.

There is also a split in philosophy. Classical reformers, such as those from Gratz, Pilates Designs and similar makers, use four springs that are all the same tension, so there are no colors at all. Pilatesology's spring guide describes each of those springs as heavy. On a classical machine you change the load by changing how many springs you hook on. Contemporary reformers give you a mix of lighter and heavier springs, marked by color, so you can make much finer adjustments.

If you trained classically, "two springs" is a complete instruction. On a contemporary machine, you will want to know which two.

A Spring Color Chart for the Main Brands

This is the chart I keep taped inside my front desk drawer, drawn from the manufacturers' published codes as collected by StudioGrowth and Pilatesology, and checked against Balanced Body's own spring listing.

Brand	Lightest	Light / Medium	Heavier	Heaviest
Balanced Body	Yellow (very light)	Blue (light)	Red (medium)	Green (heavy)
Merrithew (STOTT)	White (25%)	Blue (50%)	Red (100%)	Black (125%)
Peak Pilates	Blue (light)	Yellow (medium)	Red (heavy)	None
BASI	Yellow (light)	Blue (medium)	Red (heavy)	None
Flexia	White (very light)	Orange (light)	Blue (medium)	Black (heavy)

Classical machines are left out because their springs carry no color code. Two things jump out. Red flips between "medium" and "heavy" depending on the brand, and yellow is the lightest spring on some machines and a medium on Peak. If you move between studios, ask the instructor which spring counts as the "full" one before you set up.

A useful way to translate: on Balanced Body, instructor Sarah Bertucelli describes red as a full spring, blue as roughly half of one, yellow as roughly a quarter and green as about one and a quarter, in her Pilates Anytime workshop. That lines up neatly with Merrithew's 25, 50, 100 and 125 percent labels, even though the colors do not match.

What a Spring Actually Does as It Stretches

A spring is not a weight plate. A dumbbell weighs the same at the top of a curl as at the bottom, but a spring pulls harder the further you stretch it.

Merrithew publishes the numbers, which makes this easy to see. Its spring resistance chart lists a red reformer spring with an initial tension of 6 to 7.5 pounds and a rate of 1.25 pounds per inch of extension, and the company says to add the initial tension to the rate multiplied by the inches of stretch. By that arithmetic, a red spring pulled out ten inches is working somewhere around 19 pounds, nearly three times what it offers at rest. A white spring at the same stretch is only in the region of six pounds.

Two practical consequences follow:

• Your carriage position matters. The further the carriage travels from the springs, the more resistance you feel. FOLD Reformer's spring comparison makes the same point: move the carriage further away to make the work harder, bring it closer to make it easier.
• Your footbar or gear setting matters. Changing where the carriage starts changes how stretched the springs already are. Pilatesology suggests setting up footwork so your hip angle sits around 90 degrees or slightly deeper with your toes on the bar, and using a closer gear if you are shorter.

So two people on "one red" can have quite different workouts if one of them is tall and set up with the carriage further out.

Why a Lighter Spring Can Feel Harder

On many reformer exercises the spring is not the thing you are fighting. It is the thing holding you steady.

Think of an exercise where you hold a plank with your hands on the footbar and your feet on the carriage. A heavy spring keeps the carriage from sliding away, so it does a lot of the stabilizing for you. Take a spring off and the carriage wants to move with every wobble, and your trunk and shoulders have to do that work instead. Pilatesology puts it plainly: heavier spring tension does not indicate difficulty, because many exercises need more strength and control on a lighter spring.

Bertucelli's examples in the workshop above are ones I use in my own teaching. On prone work such as up stretch and elephant, she starts people on about a spring and a half for support, with the goal of working down to one spring as they get stronger. On scooter, a light spring makes it a core control exercise, while a heavy spring turns it into more of a glute exercise.

If a new client asks me to make an exercise harder, my first move is often to take a spring away, not add one.

Naoko Tamura-Webb

How to Choose Springs for Common Exercises

StudioGrowth's general rule is a good starting point: footwork and leg work usually use more springs, while arm and core work usually use fewer. Within that, a few principles from my studio floor:

• Footwork: this is where heavier settings live. Bertucelli says she uses three reds and a blue in her own practice, but she recommends beginners start lighter, so the pelvis stays steady while the legs press.
• Arm work: start light, often a single lighter spring, and only add load while your form holds. Shoulders creeping toward your ears means the spring is winning.
• Planks, kneeling and prone work: start with more support than you think you need, then remove spring as your control improves.
• When in doubt, use Pilatesology's test: if you feel compressed, the spring is too heavy. If you feel out of control, it is too light.

I would add one habit of my own. I change springs only when the carriage is resting home against the stopper, never mid-exercise with the springs loaded, and I teach every client to do the same. If you are working around an injury, are pregnant or have a condition that affects your joints, check with your clinician before you go heavy, and tell your instructor so they can set you up accordingly.

Where to Start

If you only remember three things, make them these. First, read the springs on the machine you are using, not the one you learned on; a red is not always a red. Second, resistance grows as the springs stretch, so your setup matters as much as your color choice. Third, lighter often means harder, especially for anything that asks you to hold still.

If you own a reformer, look after the springs. Balanced Body, Peak and STOTT all recommend replacing reformer springs about every two years under regular use, according to a round-up of manufacturer guidance from The Fit Reformer, and you should replace one sooner if you see gaps between the coils, rust or kinks. Check the underside of the carriage too, where damage tends to hide.

If you are new to the reformer, you do not need to master this before your first session. A good instructor will set your springs. Notice how each setting feels, ask what you are on, and within a few weeks you will be choosing for yourself.

Frequently asked

Is a red spring heavy or medium on a reformer?

It depends on the brand. Red is the medium spring on Balanced Body and Align-Pilates reformers, but it is the heavy spring on Merrithew (STOTT), Peak Pilates and BASI machines. Ask your instructor which spring counts as the full one.

Are more springs always harder in reformer Pilates?

No. Heavier springs add resistance for pressing work like footwork, but on many exercises the spring steadies the carriage. Planks, kneeling and prone exercises often get harder when you take a spring away.

What spring setting should a beginner use for footwork?

Start lighter than you think, so your pelvis stays steady while your legs press, and let your instructor set you up. Add spring gradually once you can keep your form through every repetition.

How often should reformer springs be replaced?

Balanced Body, Peak and STOTT all recommend replacing springs about every two years under regular use. Replace a spring sooner if you see gaps between the coils, rust or kinks.