Odds Converter

Convert between any odds format: American (+150, -200), decimal (2.50), fractional (3/2), implied probability (40%), and Kalshi contract price ($0.40).

When to Use

Use this skill when the user asks about:

• Converting odds from one format to another
• What specific odds mean (e.g., "what does -150 mean?")
• Comparing odds from different platforms that use different formats
• Implied probability of any odds value
• Kalshi contract price equivalents for sportsbook odds
• Batch converting multiple odds values

Operations

1. American Odds → All Formats

Convert a single American odds value to every other format. Replace ODDS with the value (e.g., -150 or +200):

python3 -c "
odds = ODDS
if odds < 0:
    impl = abs(odds) / (abs(odds) + 100)
elif odds > 0:
    impl = 100 / (odds + 100)
else:
    impl = 0.5
dec = round(1 / impl, 4) if impl > 0 else 0
from fractions import Fraction
frac = Fraction(1 - impl, impl).limit_denominator(100) if impl > 0 else 'N/A'
kalshi = round(impl, 2)
print(f'American: {odds:+d}')
print(f'Decimal:  {dec}')
print(f'Fractional: {frac}')
print(f'Implied Prob: {impl*100:.2f}%')
print(f'Kalshi Price: \${kalshi}')
"

2. Decimal Odds → All Formats

Convert decimal odds to every other format. Replace DEC with the value (e.g., 2.50):

python3 -c "
dec = DEC
impl = 1 / dec if dec > 0 else 0
if impl > 0.5:
    amer = round(-(impl / (1 - impl)) * 100)
elif impl < 0.5:
    amer = round(((1 - impl) / impl) * 100)
else:
    amer = 100
from fractions import Fraction
frac = Fraction(dec - 1).limit_denominator(100) if dec > 1 else '0/1'
kalshi = round(impl, 2)
print(f'Decimal:  {dec}')
print(f'American: {amer:+d}')
print(f'Fractional: {frac}')
print(f'Implied Prob: {impl*100:.2f}%')
print(f'Kalshi Price: \${kalshi}')
"

3. Fractional Odds → All Formats

Convert fractional odds to every other format. Replace NUM and DEN with numerator and denominator (e.g., 3 and 2 for 3/2):

python3 -c "
num, den = NUM, DEN
dec = round((num / den) + 1, 4)
impl = den / (num + den)
if impl > 0.5:
    amer = round(-(impl / (1 - impl)) * 100)
elif impl < 0.5:
    amer = round(((1 - impl) / impl) * 100)
else:
    amer = 100
kalshi = round(impl, 2)
print(f'Fractional: {num}/{den}')
print(f'Decimal:  {dec}')
print(f'American: {amer:+d}')
print(f'Implied Prob: {impl*100:.2f}%')
print(f'Kalshi Price: \${kalshi}')
"

4. Implied Probability → All Formats

Convert an implied probability to every other format. Replace PROB with the probability as a decimal (e.g., 0.40 for 40%):

python3 -c "
impl = PROB
dec = round(1 / impl, 4) if impl > 0 else 0
if impl > 0.5:
    amer = round(-(impl / (1 - impl)) * 100)
elif impl < 0.5:
    amer = round(((1 - impl) / impl) * 100)
else:
    amer = 100
from fractions import Fraction
frac = Fraction(1 - impl, impl).limit_denominator(100) if impl > 0 else 'N/A'
kalshi = round(impl, 2)
print(f'Implied Prob: {impl*100:.2f}%')
print(f'American: {amer:+d}')
print(f'Decimal:  {dec}')
print(f'Fractional: {frac}')
print(f'Kalshi Price: \${kalshi}')
"

5. Batch Convert

Convert a list of American odds values to all formats at once. Replace the list with actual values:

python3 -c "
odds_list = [-150, +200, -110, +300, -400]
print(f'{\"American\":>10} {\"Decimal\":>10} {\"Implied\":>10} {\"Kalshi\":>10} {\"Fractional\":>12}')
print('-' * 56)
for odds in odds_list:
    if odds < 0:
        impl = abs(odds) / (abs(odds) + 100)
    elif odds > 0:
        impl = 100 / (odds + 100)
    else:
        impl = 0.5
    dec = round(1 / impl, 4)
    from fractions import Fraction
    frac = Fraction(1 - impl, impl).limit_denominator(100)
    kalshi = round(impl, 2)
    print(f'{odds:>+10d} {dec:>10.2f} {impl*100:>9.1f}% {\"$\" + str(kalshi):>10} {str(frac):>12}')
"

Output Rules

1. Always show ALL five formats in conversion output
2. American odds must include the +/- sign (e.g., +150, -200)
3. Decimal odds to 2-4 decimal places depending on value
4. Implied probability as a percentage with 1-2 decimal places
5. Kalshi price as a dollar value between $0.01 and $0.99
6. Fractional odds simplified to lowest terms with denominator ≤ 100
7. For batch conversions, use a table format with aligned columns
8. When a user says "what does X mean" — convert to all formats AND explain in plain English (e.g., "-150 means you risk $150 to win $100, implying a 60% chance")

Error Handling

• If the user provides odds of exactly 0, explain that 0 is not valid in any odds format
• If the user provides implied probability > 1.0 or < 0, ask if they meant a percentage (e.g., 60 → 0.60)
• If the user provides decimal odds ≤ 1.0, explain that decimal odds must be greater than 1.0
• If the user gives a fraction with 0 denominator, explain it's invalid
• If the format is ambiguous (e.g., "150"), ask whether they mean +150 American or 1.50 decimal

About

Built by AgentBets — full tutorial at agentbets.ai/guides/openclaw-odds-converter-skill/.

Part of the OpenClaw Skills series for the Agent Betting Stack.