Swim Speed D&D: How to Calculate It

This calculator works out a character’s swim speed in Dungeons & Dragons 5e, converting a chosen base speed into the distance they can cover while swimming in a single round. You enter the creature’s base walking speed in feet, and the calculator returns the swim speed in feet per round, using the standard rule that swimming costs 1 extra foot of movement per foot traveled unless a swim speed is listed. It also shows the equivalent distance in meters for quick reference.

Formula

The core rule is simple: Swim Speed = Base Speed (in feet per round).

In D&D 5e, every creature has a speed measured in feet per round (a round is 6 seconds). If a creature has a listed swim speed, that number replaces its walking speed when moving through water. If no swim speed is listed, the creature can still swim, but each foot of movement costs 1 extra foot (so effectively half speed). The calculator assumes you are using the listed swim speed, which is the same as the base speed for most creatures that have one.

Variables:

• Base Speed (ft): The creature’s walking speed in feet per round, as shown on its stat block.
• Swim Speed (ft/round): The distance the creature can swim in one round.
• Swim Distance (m): The same distance converted to meters (1 ft = 0.3048 m).

Worked Example

Using the default values from the calculator above:

1. Base Speed = 30 ft.
2. Swim Speed = 30 ft/round (since the swim speed equals the base speed).
3. Swim Distance in meters = 30 × 0.3048 = 9.144 m, which rounds to 9.1 m.

So a creature with a 30 ft base speed swims 30 feet per round, or about 9.1 meters.

When to Use This

Use this calculator when you need to know how far a character can swim in combat or during a timed chase. It is also handy for planning underwater encounters, determining if a character can reach a sinking ally, or calculating travel time across a lake. The result is the maximum distance in a single round; for longer swims, multiply by the number of rounds (or use the standard travel pace rules for overland movement).

How to Read the Result

The swim speed is a distance, not a rate per second. In D&D, a round is 6 seconds, so a swim speed of 30 ft means the character moves 30 feet in 6 seconds, which is 5 feet per second. The meter conversion helps if you are using a grid in meters or playing with a group that prefers metric.

Common Mistakes

• Forgetting the extra movement cost: If a creature has no swim speed, swimming costs 2 feet of movement per 1 foot traveled. The calculator assumes a swim speed is present; if not, divide the result by 2.
• Confusing speed with distance per turn: Speed is already the distance per round, so do not multiply by 6 or divide by 6. The number on the stat block is the distance per round.
• Mixing feet and meters: The base speed is in feet; if you enter meters, the result will be wrong. Use the meter output for conversions.
• Ignoring difficult terrain: Underwater, certain obstacles or currents may count as difficult terrain, halving effective speed. This calculator does not account for that.

Tips

• Check the stat block: Many aquatic creatures have a swim speed different from their walking speed (e.g., a shark has swim 40 ft, walk 0 ft). Enter the swim speed directly if it is listed.
• For characters without a swim speed, remember the rule: each foot of swimming costs 1 extra foot of movement. So a 30 ft speed character can swim 15 ft per round.
• Use the meter output for battle maps that use metric grids, but keep the feet value for official rules.
• If you are a DM, this calculator helps you quickly adjudicate underwater chases or escapes.

Troubleshooting

If the result seems too high or too low: Double-check the base speed you entered. A typical human is 30 ft, but some races have 25 ft or 35 ft. Also verify whether the creature has a swim speed listed; if not, halve the result.

If you need to account for difficult terrain: The calculator does not apply the difficult terrain penalty. To get the effective speed, divide the result by 2.

If you are using a different edition: This is for D&D 5e. In earlier editions, swimming rules differ (e.g., 3.5e uses a Swim skill with movement fractions). This calculator is not applicable to those systems.

If the meter conversion looks odd: The conversion factor is exact (1 ft = 0.3048 m), but the calculator rounds to one decimal place. For most purposes, 30 ft is about 9 m.

Frequently Asked Questions

Q: What if my character doesn’t have a swim speed?
A: Without a swim speed, each foot of swimming costs 1 extra foot of movement. So a character with a 30 ft speed can swim 15 ft per round. You can use the calculator by entering your base speed and then dividing the result by 2.

Q: Does a swim speed also apply to diving?
A: Yes, swim speed applies to any movement through water, including diving vertically. The same distance per round applies.

Q: Can I use this for long-distance swimming?
A: For long distances (over 1 minute), D&D uses travel pace rules. A normal pace covers 3 miles per hour, which is about 24 miles per day. Swim speed does not directly convert to overland travel; use the standard travel rules instead.

Q: What about flying or climbing speeds?
A: This calculator is only for swimming. Flying and climbing have their own rules (climbing also costs extra movement without a climb speed). You would need a separate calculator for those.

Q: Why is the swim speed the same as the base speed?
A: In D&D 5e, if a creature has a swim speed, it is usually equal to its walking speed unless stated otherwise. The rule is that a creature with a swim speed can move through water at that speed without the extra movement penalty.

Q: How do I handle a creature with a swim speed but no walking speed?
A: Some creatures, like fish, have a swim speed but a walking speed of 0 ft. In that case, enter the swim speed as the base speed, and the result will be correct for swimming. They simply cannot walk.

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in base | Base Speed | ft | 30 | 0
out swim | Swim Speed | ft/round | base | 0
out swim_m | Swim Distance (m) | m/round | base * 0.3048 | 1