What AmpSizer provides
AmpSizer is a reference and calculation tool. It publishes numeric table data transcribed from the 2023 NEC, published by NFPA, and provides calculators built on that data. The edition is cited on every page that reports a value.
Not the code, and not affiliated with it
AmpSizer reproduces no code text. It is not affiliated with, endorsed by, sponsored by, or approved by NFPA or any code-making body. It is not a code service and it is not a substitute for the code document itself, which contains the actual requirements along with the exceptions and conditions the tables depend on.
Safety disclaimer
Everything on this site is a reference estimate. Electrical work is dangerous and incorrect conductor sizing is a fire hazard. Final conductor sizing, overcurrent protection, and installation methods must be determined by a licensed electrician and approved by your authority having jurisdiction. Code editions are adopted and amended locally, so the edition cited here may not be the one enforced where you are.
The calculators make simplifying assumptions and do not model many real conditions - including motor and air conditioning circuits, paralleled conductor sets, service and feeder load calculations, conductor reactance and power factor, installation methods other than raceway, and local amendments. Do not rely on any figure here as the sole basis for installing, modifying, or approving electrical work.
No warranty
AmpSizer is provided "as is" without warranty of any kind, express or implied. While every published figure is validated on build against known values and for internal consistency, we do not warrant that the data is complete, current, or free of error, and we accept no liability for any loss, injury, or damage arising from its use.
Subscriptions
Premium subscriptions are sold through RevenueCat and Stripe. Subscriptions renew automatically until cancelled, and can be cancelled at any time from the link in your receipt email. Lifetime is a one-time payment. Access is tied to the browser you purchased in and can be moved with your access code - see Restore access.
The free tier - every table, every reference page, and all four calculators - is not time-limited and does not require an account.
Refunds
Not happy with a purchase? Email [email protected] within 14 days of a first purchase, or within 7 days of a renewal, and we will refund it. Send the message from the email address you used at checkout, and include:
- the email address used at checkout (if you are writing from a different address)
- your access code, shown on the Premium page while you are signed in on the browser you purchased from
- roughly when you purchased, and which plan (weekly, yearly or lifetime)
- the last 4 digits of the card, if you have the receipt handy
That is everything needed to find the purchase and process the refund. This policy does not limit any statutory rights you may have.
Acceptable use
You may use AmpSizer for your own professional or personal work, including in commercial projects. You may not scrape or bulk-redistribute the site's generated pages as a competing dataset or service.
Changes
These terms and the underlying data may be updated as code editions change. Continued use after a change constitutes acceptance.