Updated for 2026 • All calculators free • No signup required
For family planning in 2026, the most important calculators are due date (pregnancy timeline), baby costs (first-year budget), and nursery costs (childcare expenses in the UK). Boring Math's Baby Cost Calculator covers everything from nappies to car seats. For UK parents, the Nursery Cost Calculator includes the 30 free hours entitlement. For fertility planning, the Ovulation Calculator identifies your most fertile days. All calculators are free with no signup.
Estimates your baby's due date based on last menstrual period or conception date, with trimester timeline and key milestones.
Best for: Expecting parents wanting to know their due date and pregnancy timeline.
Open calculator →Estimates the total cost of a baby's first year including nappies, formula, clothing, equipment, and childcare.
Best for: Parents-to-be budgeting for their first child.
Open calculator →Calculates annual nursery costs based on hours, days, and region, including the 30 free hours entitlement for 3-4 year olds.
Best for: UK parents evaluating childcare options and costs.
Open calculator →Estimates your most fertile days and ovulation date based on cycle length and last period start date.
Best for: Anyone trying to conceive and wanting to identify their fertility window.
Open calculator →Estimates the annual and lifetime cost of owning a dog, cat, or other pet including food, vet bills, insurance, and grooming.
Best for: Anyone considering getting a pet and wanting to understand the real costs.
Open calculator →Converts dog age to human years using the updated scientific method based on breed size, not the old 7x rule.
Best for: Dog owners curious about their pet's age in human equivalent years.
Open calculator →| Calculator | Best for | Free | No account needed | Updated 2026 |
|---|---|---|---|---|
| Due Date Calculator | Expecting parents wanting to know their due date and pregnancy timeline | Yes | Yes | Yes |
| Baby Cost Calculator | Parents-to-be budgeting for their first child | Yes | Yes | Yes |
| UK Nursery Cost Calculator | UK parents evaluating childcare options and costs | Yes | Yes | Yes |
| Ovulation Calculator | Anyone trying to conceive and wanting to identify their fertility window | Yes | Yes | Yes |
| Pet Cost Calculator | Anyone considering getting a pet and wanting to understand the real costs | Yes | Yes | Yes |
| Dog Age Calculator | Dog owners curious about their pet's age in human equivalent years | Yes | Yes | Yes |
A due date is calculated by adding 280 days (40 weeks) to the first day of your last menstrual period (LMP). This is called Naegele's rule. If you know your conception date, the due date is 266 days (38 weeks) from conception. Most babies arrive within two weeks either side of the estimated due date, so it is a guide rather than a guarantee.
The average first-year cost of a baby in the UK ranges from £6,000 to £12,000 depending on choices around feeding, childcare, and equipment. The biggest expenses are typically childcare (nursery or childminder), a pushchair and car seat, and nappies. Breastfeeding saves significantly over formula, and buying second-hand equipment can cut costs by 40-60%.
Full-time nursery in the UK costs between £12,000 and £18,000 per year on average, with London significantly higher at up to £25,000+. Part-time options reduce costs proportionally. Parents of 3 and 4 year olds can claim 30 free hours per week during term time, and the government has been extending free hours to younger children from 2024 onwards.
You are most fertile in the five days before ovulation and the day of ovulation itself, giving a roughly six-day fertile window each cycle. Ovulation typically occurs 14 days before your next period starts. For a 28-day cycle, that means around day 14. The Ovulation Calculator adjusts for your actual cycle length to give a more accurate estimate.
A dog in the UK costs between £1,500 and £3,000 per year on average. Food is the largest recurring cost (£400-£800), followed by pet insurance (£300-£600), vet bills and vaccinations (£200-£500), and grooming (£100-£400 depending on breed). Lifetime costs over 10-13 years can reach £20,000 to £35,000.
The old "multiply by 7" rule is inaccurate. Modern research shows dogs age rapidly in their first two years, then slow down. A more accurate method accounts for breed size: small dogs age more slowly than large dogs after the first two years. A 5-year-old Labrador is roughly equivalent to a 40-year-old human, while a 5-year-old Chihuahua is closer to 36. The Dog Age Calculator uses breed-size-adjusted formulas for a more accurate result.
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