Pulse and heart rate are closely related but not technically the same thing. Most of the time, the two numbers match perfectly, which is why even the American Heart Association uses the terms interchangeably in its public guidelines. But they measure different physical events, and in certain health conditions, the numbers can diverge in ways that matter.
What Each One Actually Measures
Your heart rate is the number of times your heart squeezes per minute. It’s an electrical event. Each heartbeat is triggered by an electrical impulse that travels through the heart muscle and tells it to contract. To directly measure heart rate, a device needs ECG (electrocardiogram) technology that detects those electrical signals.
Your pulse is the number of times your arteries expand and contract in response to blood being pushed through them. When you press two fingers against your wrist or neck and feel a rhythmic thump, you’re not feeling your heart squeeze. You’re feeling the pressure wave that arrives a fraction of a second later as blood surges into the artery and briefly stretches the vessel wall.
Think of it this way: heart rate is measured at the source (the heart’s electrical system), while pulse is measured downstream (the arteries). In a healthy person with a normal heart rhythm, every electrical signal produces a heartbeat, and every heartbeat produces a pulse. The two numbers are identical, which is why checking your pulse at the wrist is a perfectly reliable way to know your heart rate in everyday life.
When the Two Numbers Don’t Match
The gap between heart rate and pulse rate is called a pulse deficit, and it shows up most commonly in atrial fibrillation, a condition where the heart beats irregularly. During atrial fibrillation, some heartbeats are so weak or poorly timed that they don’t push enough blood into the arteries to create a detectable pulse at the wrist. The heart contracts, but the pulse never arrives.
In a study of 273 people with permanent atrial fibrillation, the average pulse deficit was 12 to 17 beats per minute depending on the person’s exercise tolerance. That means for every minute, a dozen or more heartbeats were essentially “empty,” producing no meaningful blood flow to the rest of the body. People with larger pulse deficits had significantly worse exercise capacity.
A pulse deficit greater than 10 beats per minute is generally considered worth investigating, especially when paired with symptoms like fatigue, dizziness, or shortness of breath. Measuring it requires counting the actual heartbeat (listened to with a stethoscope placed on the chest) at the same time as counting the pulse at the wrist, then subtracting. If a stethoscope picks up 90 beats per minute at the heart but only 72 pulses reach the wrist, the deficit is 18, meaning 18 contractions per minute aren’t pushing blood effectively.
Peripheral artery disease can also cause a weaker or absent pulse at certain locations, not because the heart is misfiring but because narrowed or stiffened arteries are blocking the pressure wave before it reaches your fingertips or feet.
What Your Wearable Is Actually Reading
Most fitness trackers and smartwatches don’t measure heart rate in the strict sense. They measure your pulse. The sensor on the back of the watch shines light into your skin and detects how much light is absorbed or reflected as blood flows through tiny vessels. Each time your heart pushes a new surge of blood, the sensor picks up the change and counts it as a beat. This optical method is called photoplethysmography, or PPG.
Some newer smartwatches also include a single-lead ECG feature. To use it, you typically place a finger from your opposite hand on a button or sensor on the watch, creating a small electrical circuit across your chest. This records the heart’s actual electrical activity, similar to a simplified version of what you’d get in a clinic.
Interestingly, for detecting atrial fibrillation, the optical (pulse-based) smartwatches have performed well in research. A large meta-analysis found PPG-based watches detected atrial fibrillation with 97.4% sensitivity, compared to 83% for ECG-based watches. That said, both technologies are screening tools, not replacements for a full clinical ECG with multiple leads.
Where You Can Feel a Pulse
You can detect a pulse anywhere an artery runs close enough to the surface to be pressed against something firm, like bone. The two most familiar spots are the radial artery on the thumb side of your inner wrist and the carotid artery on either side of your neck. But there are several others:
- Inside of the elbow: the brachial artery, just above the crease where blood pressure cuffs are placed
- Groin: the femoral artery, below the crease where your leg meets your torso
- Behind the knee: the popliteal artery, found in the soft area at the back of the knee
- Behind the ankle bone: the posterior tibial artery, just behind the bony bump on the inside of your ankle
- Top of the foot: the dorsalis pedis artery, on the upper surface of the foot near the big toe’s tendon
Checking pulses at these different locations can reveal circulation problems. A strong pulse at the wrist but a weak or absent one at the top of the foot, for example, could signal reduced blood flow in the legs.
The Practical Takeaway
For most people in most situations, pulse and heart rate give you the same number and can be used interchangeably. If you’re checking your resting rate by holding your fingers to your wrist for 15 seconds and multiplying by four, or glancing at your smartwatch during a workout, you’re getting a reliable picture of how fast your heart is beating. The distinction between the two only becomes clinically important when the heart isn’t beating in a regular, effective rhythm, at which point some beats get “lost” between the heart and the arteries. If you’ve ever noticed your wearable giving erratic readings or skipping beats, an irregular rhythm is one possible explanation worth paying attention to.