2026-09-16 9 min

Swim Pace Calculator

Swim pace computer: time per 100 from any swim.

Calculator

Pace Input sec

Second Input sec

Weight kg

Results update live as you type

Status:1:40 /100mCSS sets zonesScore 82/100

Swim Pace Calculator Results

Score82

Answer1:40 /100m

Context100 s per 100 m

BasisFit lap pace

MethodStroke + walls matter

NextCSS sets zones

pace: 1:40 /100m — 100 s per 100 m. CSS sets zones.

Pace Breakdown

Measure	Value	Context
Answer	1:40 /100m	primary result
Context	100 s per 100 m	supporting pace
Basis	Fit lap pace	input-derived
Method	Stroke + walls matter	convention
Reference	Pace-anchored zones	zone check
Next	CSS sets zones	action

Recommendations

▸Test 200/400 rested with the same warm-up each cycle.
▸Hold endurance sets just under CSS, intervals just over.
▸Add 5-15 s/100 for open-water predictions.
▸pace: 1:40 /100m — 100 s per 100 m. CSS sets zones.

Results

Optimal

Score

82/100

Rating

Answer

1:40 /100m

Main result

Context

100 s per 100 m

Context

Basis

Fit lap pace

Basis

Method

Stroke + walls matter

Method

CSS sets zones

Action

Standard endurance equations and pacing conventions; field estimates run within ~5-10% with honest inputs.

Visualizations

Gauges

100Main

50Support

40Detail

Score vs 100

Score100%

Gap0%

Swim Score

Score82/100

Formula

Standard endurance math.

Threshold-anchored equation

Alternative Form

Race-day discount variants

Variables

Symbol	Name	Unit	Description
A	Input one	-	Test/measure
B	Input two	-	Weight/time
C	Context	-	Zone/course
R	Answer	-	Result
S	Score	0-100	Rating

Explanation

Threshold-anchored endurance math on honest test data.

Derivation

Coggan/Allen power and Maglischo swim conventions.

Step-by-Step Calculation

Follow each step to understand how the result is calculated from your inputs.

Step 1

Enter test numbers.

Direct inputs

Tests:as measured

Intermediate: direct

Result: Inputs set

Step 2

Apply the equation.

Standard formula

Mode:selected

Intermediate: compute

Result: Raw answer

Step 3

Anchor to threshold.

FTP/CSS zones

Anchor:threshold

Intermediate: lookup

Result: Zone context

Step 4

Discount for racing.

5-10% race haircut

Race:plan

Intermediate: adjust

Result: Race-ready target

Step 5

Name the action.

Prescription map

Result:computed

Intermediate: map

Result: Action read

Step 6

Score the result.

Completeness

Result:computed

Intermediate: score

Result: Score set /100

Final Answer

82/100

Worked Examples

See how the calculator works with different scenarios.

Scenario

Typical test data.

Inputs

First:default

Calculation

Equation applied

Result

Answer computed

Interpretation

Test rested for your numbers.

Understanding Your Result

Your Result: Score: 82/100

Typical range: FTP zones 55-120%; CSS from 200/400 trials; Ironman 8-17 h; TSS 100 = one hard hour.

What This Means

The output converts pool times into paces, CSS, zones, intervals and open-water predictions.

Why It Matters

Pace-anchored swimming turns lap counting into structured sets with predictable race times.

Professional Interpretation

Endurance coaches anchor zones to tested thresholds, then pace races a fixed discount below them.

Tests vs races

Fresh tests overstate race-day durability by 5-10% — discount accordingly.

Steady beats surge

Even pacing wins endurance events; surges cost multiples of their gains.

Recommendations

•Test thresholds rested
•Pace races below tests
•Practice fueling in training
•Taper into key events

Educational Content

Introduction

This calculator turns test numbers and course data into zones, paces and finish predictions.

Concept Explanation

Thresholds anchor zones; zones anchor pacing; pacing plus transitions anchor finish times.

Applications

▸FTP testing

▸Zone setup

▸Climb pacing

▸CSS testing

▸Race prediction

▸Fuel planning

Benefits

•Exact zone watts/paces
•Finish predictions
•Split targets
•Stress scores
•Gear/speed answers

Limitations

•Estimate error ~5-10%
•Wind/heat unmodeled
•Drafting unmodeled
•Course profile simplified
•Day-form variance

Best Practices

•Test rested and fueled
•Same protocol each time
•Discount tests for racing
•Rehearse transitions
•Re-test every 6-8 weeks

Common Misconceptions

Myth: Higher FTP always wins.

Truth: Durability and fueling decide long races more than threshold watts.

Myth: Pool pace equals open water.

Truth: Sighting, chop and crowds add 5-15 s per 100 m.

Myth: Race-day nutrition experiments work.

Truth: Nothing new on race day — gut training is real training.

Practical Tips

•Warm up before tests
•Pace tests evenly
•Log conditions
•Practice race kit
•Rehearse feeds
•Taper key races

Common Mistakes

Testing tired

Fatigued tests understate zones and poison training for weeks.

Starting too hard

First-km heroics bill the final third at triple rates.

Ignoring transitions

Minutes hide in wetsuit strips and flying mounts — practice them.

New gear on race day

Untested saddles, suits and shoes injure. Race proven kit only.

Under-fueling long races

60-90 g carbs hourly past 2.5 hours; practice it.

No heat plan

Hot races demand 1-3% pace discounts plus extra sodium.

Assumptions

This calculator makes the following assumptions to provide estimates:

Steady conditions: Calm, flat-equivalent efforts unless grade set.

Honest inputs: Test power, distances and times are measured.

Typical equipment: Road setup; TT gear shifts bike splits.

Adult athletes: Zones fit trained adults.

Field-grade: Estimates, not lab measures.

Limitations

Be aware of these limitations when using this calculator:

Wind ignored: Headwinds cost like grades.

Heat ignored: Hot races slow all three sports.

Drafting ignored: Legal packs save large bike watts.

Course simplified: Rolling profiles differ from averages.

Day variance: Sleep, fuel and illness move results.

Frequently Asked Questions

Answers to common questions about this calculator.

What is swim pace per 100 m?

Time to swim 100 meters — the standard way swimmers compare efforts, set intervals and predict races.

How do I convert per 100 yd to per 100 m?

Multiply per-100-yd pace by 1.0936. A 1:30 per 100 yd equals about 1:38 per 100 m.

What is a good swim pace?

Recreational 2:00-2:30 per 100 m; fit lap swimmers 1:30-2:00; competitive age-groupers under 1:30.

What is CSS?

Critical swim speed — fastest pace sustainable ~30 minutes, from 400 m and 200 m trials. Endurance just below, intervals just above.

How do turns matter?

Good walls save 1-2 s per 25 m. Open water without walls runs slower than equal pool pace.

How do I pace open water?

Add 5-15 s per 100 m to pool pace for sighting, currents and chop; swim the first third conservatively.

What interval should I swim on?

A send-off 10-20 s above repeat pace keeps rest consistent. If rest collapses, lengthen the interval.

How do pool lengths work?

Distance = lengths x pool length. In 25 m pools, 40 lengths is 1,000 m; in 50 m pools, 20 lengths.

How do wetsuits change pace?

Typically 3-8 s per 100 m faster through buoyancy and warmth, more for weaker kickers.

How many calories does swimming burn?

Roughly 500-700 per hour moderate for 70 kg (MET 8-10); fast sets exceed 800.

Freestyle vs other strokes?

Freestyle fastest, then backstroke, breaststroke, butterfly. Stroke changes shift pace 10-30 s per 100 m.

How often to test CSS?

Every 6-8 weeks with the same warm-up and rested state. Improvements of 1-3 s per 100 m are excellent.

Related Calculators

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Related Guides

Deepen your understanding with these educational resources.

Getting Started with Strength Training

Progressive overload, volume landmarks and recovery basics.

Cardio Training Essentials

Zones, VO2 max and weekly aerobic volume that actually moves fitness.

Nutrition for Active People

Protein, calories and hydration to support training and recovery.

Understanding Recovery

Sleep, rest days and deloads that turn training into adaptation.

Glossary

Technical terms used in mortgage calculations explained in plain language.

Pace/100m: Seconds per 100 meters.
Pace/100yd: Seconds per 100 yards; x1.0936 to meters.
CSS: Critical swim speed; ~30-min max pace.
Send-off: Interval start-to-start time.
Open water: No-wall swimming with sighting costs.
Drafting: Feet-riding saving ~20% effort.
Stroke rate: Strokes per minute.
SWOLF: Time plus strokes per length; efficiency gauge.
Threshold: CSS-adjacent sustainable pace.
Kick: Leg propulsion share; wetsuits reduce need.
Pull buoy: Isolation tool for upper-body sets.
Taper: Reduced volume before races.

Authoritative References

Trusted sources and standards referenced by this calculator.

ACSM — Exercise guidance and resources NSCA — Strength and conditioning resources NIH — Exercise and health information AtlasCalcs — Health resources

Applicable Standards

ACSM Guidelines for Exercise Testing and PrescriptionWorld Triathlon competition guidance (reference)USA Cycling coaching references

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Page Information

Last Updated:

2026-09-16

Version:

2.0.0

References:

License:

Free to use for educational and professional purposes.